Water Source Heat Pumps FAQ
Bosch WSHP R410A - R454B Crossover Guide
I need help understanding the changes between Bosch’s R-410A water source heat pumps and the new R-454B models. Where can I find information to help me?
To help our customers with comparing our outgoing R-410A water source heat pump models with our new R-454B models, we have created this crossover guide: Bosch WSHP Crossover Matrix.
For general information regarding the A2L refrigerant change and how Bosch Home Comfort is transitioning our products to R454B, please visit our A2L Refrigerant Change Guide.
RP Models
If I ever have to adjust the refrigerant levels in this product, is it ok to use R-410A?
No.
This product is designed and approved to use R-454B refrigerant only. Do not attempt to mix in any other type of refrigerant.
For more details regarding R-454B refrigerant, please visit our A2L Refrigerant Change Guide.
Do these units include refrigerant leak detection sensors, and if so, how do they work?
Equipment containing 64oz or more of refrigerant will be factory equipped with a leak detection sensor. Should this sensor detect a refrigerant leak, a fault will occur.
The unit controller will react by turning off the compressor and energize the blower which will dissipate the refrigerant.
What setting do the new RP Controller DIP switches control?
The 8 DIP switches allow for configuration of settings critical to unit commissioning such as Test Mode, freeze protection set point, how lockouts are reset, dehumidification control, down-staging functionality, alarm signal type, and activation and configuring of the optional HRP.
Each of these settings can still be controlled through the EasyStart app, the DIP switches simply serve as an alternative. For further information please refer to the EasyStart IOM.
How will I update the firmware for the RP Controller?
RP series units come factory equipped with the latest firmware.
The latest version of the unit’s firmware is contained within the the EasyStart app.
Any future improvements to the firmware will be made available through updates to the app, and the app can then be used to flash updated firmware to the RP controller.
Do RP series units include swivel fittings for water connections?
No, RP series units do not include swivel water connections.
However, optional stainless steel hose kits can be purchased with swivel fittings if the application requires them.
I’ve noticed that the compressor is still running even though the Y-call has ended. Is this a problem?
No, this is perfectly normal and is a new function that adds the benefit of minimizing wear and tear on the compressor over time.
The UPM in all of our R-454B water source heat pump products includes a minimum compressor run time of five minutes.
If Y-call is removed, the compressor will remain energized until the five minutes have expired.
This wasn't the case with our legacy R-410A models, and therefore may be confusing to customers who are familiar with those products and now installing our new R-454B models.
I hear noises when the heat pump Is running. What could they be, and can I reduce them?
When operating, there will of course be audible sounds coming from the unit itself, or even from the air ducts and water piping in your property.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
Air Flow Noise
Poor Air Duct And/Or Grille Design
- Ensure that all ductwork and grilles are correctly sized for the unit's air flow.
- Check for blockages or damage to the air ducts and grilles.
Fan Speed Setting Too High
- Consult the blower performance table in the product manual.
Structural Noise
Unit Not Mounted On A Full Anti-Vibration Pad
- Mount the unit on a suitable anti-vibration pad.
Unit Has Been Connected With Solid Installation Hardware Instead Of Flexible Hardware.
- All electrical conduit, water lines, and duct work connection to the unit should be flexible, as this will help prevent noises and vibrations from being transferred from the unit to the structure. Please refer to the manual for correct installation guidelines.
The Unit Is Physically Touching A Wall Or Other Part Of The Building
- Adjust the unit's mounting location to avoid physical contact with any part of the building's structure.
Compressor Noise
Elevated Head Pressure Caused By High Water Temperature Or Low Water Flow Rate (in cooling mode)
- If possible, reduce the water temperature or increase the water flow rate.
Scaled Or Dirty Water Coil
- Descale and clean the water coil.
Elevated Head Pressure Caused By Low Air Flow (in heating mode)
- Check the air filter for clogging.
- Check the duct work for blockages or damage.
- Increase the fan speed.
Water Hammer
Fast closing valves were used when installing the unit.
- Replace the fast closing valves with a slow-close type instead.
Can the water coil be acid cleaned?
Yes.
Please refer to the Acid Cleaning service bulletin under "All Water Source Heat Pumps" for further details of how to clean the water coil on this page.
CP Models
If I ever have to adjust the refrigerant levels in this product, is it ok to use R-410A?
No.
This product is designed and approved to use R-454B refrigerant only. Do not attempt to mix in any other type of refrigerant.
For more details regarding R-454B refrigerant, please visit our A2L Refrigerant Change Guide.
Do these units include refrigerant leak detection sensors, and if so, how do they work?
Equipment containing 64oz or more of refrigerant will be factory equipped with a leak detection sensor. Should this sensor detect a refrigerant leak, a fault will occur.
The unit controller will react by turning off the compressor and energize the blower which will dissipate the refrigerant.
I’ve noticed that the compressor is still running even though the Y-call has ended. Is this a problem?
No, this is perfectly normal and is a new function that adds the benefit of minimizing wear and tear on the compressor over time.
The UPM in all of our R-454B water source heat pump products includes a minimum compressor run time of five minutes.
If Y-call is removed, the compressor will remain energized until the five minutes have expired.
This wasn't the case with our legacy R-410A models, and therefore may be confusing to customers who are familiar with those products and now installing our new R-454B models.
The fan runs, but the compressor is not operating. The UPM board's LED is blinking THREE times. What should be checked?
This indicates that a "Condenser Freeze Condition" has been detected.
A condenser freeze may only occur in heating mode when the water coil is now on the low pressure side of the refrigeration operation.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
Low (or no) Water Flow Through The Coil
- Check water valves and pumps for correct operation.
- Check for blockage in the water coil.
Low Water Temperature
- Check the water temperature, is it below 40º entering?
- Is the heat pump connected to a closed loop with antifreeze? If so, check that the "FREEZE 1" resistor on the UPM board has been cut to set the unit to antifreeze mode.
Low Refrigerant
- Check refrigerant pressure with your gauge set.
Poor Water Heat Exchange
- Check for scaled water coil.
For full details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page.
The fan runs, but the compressor is not operating. The UPM board's LED is blinking FOUR times. What should be checked?
This indicates that a "Condensate Overflow Fault" has been detected.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
Poor Condensate Drainage
- Check the condensate pan to see if the water level is high.
- Check the drain line and pan for blockages, inadequate trapping, or double-trapping.
Blocked Return Air
- Check air filter for clogging.
- Check return air duct for blockages.
- In free-return applications, check that there is adequate space between the return air opening and walls (or other obstructions).
For full details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page.
The fan runs, but the compressor is not operating. The UPM board's LED is blinking SIX times. What should be checked?
This indicates that an "Evaporator Freeze Condition" has been detected.
An evaporator freeze may only occur in cooling mode when the air coil is now on the low pressure side of the refrigeration operation.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
Freeze Fault, Air Coil - No (Or Low) Air Flow
- Check fan motor for correct operation.
- Check air filter for clogging.
- Inspect air coil for dirt or debris clogging.
- Check duct work for obstructions (including if dampers are closed or blocked).
Freeze Fault, Air Coil - Blocked Return Air
- In free-return applications, check that there is adequate space between the return air opening and walls (or other obstructions).
Freeze Fault, Air Coil - Low Refrigerant
- Check refrigerant pressure with your gauge set.
For full details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page.
The fan runs, but the compressor is not operating. The UPM board's LED is blinking SEVEN times. What should be checked?
This indicates that the built-in sensor system may have detected a refrigerant leak inside the heat pump.
In this event, the on-board UPM board will shut down the compressor and run the blower to reduce the levels of built-up refrigerant inside the air in the cabinet to below 15% LFL. If you cycle the power to the unit off and back on after that point the compressor will turn back on and the heat pump will operate normally.
If the problem occurs again though we recommend turning the power to the product off and having a professional who is trained to work with R-454B refrigerant inspect the product to identify if a leak is truly present and to address it.
Once the leak has been resolved it's critical to use ONLY R-454B refrigerant to replace any that was lost from the system.
For full details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page.
The fan runs, but the compressor is not operating. There are NO blinks on the UPM board's LED.
This may indicate that the contactor is not energizing.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
Is The Thermostat Calling For Compressor To Operate And Is It Sending 24vac To The Heat Pump?
- Ensure that thermostat is on and is calling for "Y".
- Check "Y" connection from thermostat, and ensure that there is 24vac across "Y" and "C" terminals in heat pump when thermostat is calling.
Possible Loose Wire To Contactor Coil
- Check wiring to ensure that there is 24vac across the contactor coil.
Potential Failed Contactor Coil
- Test contactor with 24vac across "R" and "C".
- Ohm out the contactor coil. Open circuit indicates that the coil has failed.
For full details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page.
I hear noises when the heat pump Is running. What could they be, and can I reduce them?
When operating, there will of course be audible sounds coming from the unit itself, or even from the air ducts and water piping in your property.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
Air Flow Noise
Poor Air Duct And/Or Grille Design
- Ensure that all ductwork and grilles are correctly sized for the unit's air flow.
- Check for blockages or damage to the air ducts and grilles.
Fan Speed Setting Too High
- Consult the blower performance table in the product manual.
Structural Noise
Unit Not Mounted On A Full Anti-Vibration Pad
- Mount the unit on a suitable anti-vibration pad.
Unit Has Been Connected With Solid Installation Hardware Instead Of Flexible Hardware.
- All electrical conduit, water lines, and duct work connection to the unit should be flexible, as this will help prevent noises and vibrations from being transferred from the unit to the structure. Please refer to the manual for correct installation guidelines.
The Unit Is Physically Touching A Wall Or Other Part Of The Building
- Adjust the unit's mounting location to avoid physical contact with any part of the building's structure.
Compressor Noise
Elevated Head Pressure Caused By High Water Temperature Or Low Water Flow Rate (in cooling mode)
- If possible, reduce the water temperature or increase the water flow rate.
Scaled Or Dirty Water Coil
- Descale and clean the water coil.
Elevated Head Pressure Caused By Low Air Flow (in heating mode)
- Check the air filter for clogging.
- Check the duct work for blockages or damage.
- Increase the fan speed.
Water Hammer
Fast closing valves were used when installing the unit.
- Replace the fast closing valves with a slow-close type instead.
Can the water coil be acid cleaned?
Yes.
Please refer to the service bulletin on Acid Cleaning under "All Water Source Heat Pumps" on this page for further details of how to clean the water coil.
RF Models
If I ever have to adjust the refrigerant levels in this product, is it ok to use R410A?
No.
This product is designed and approved to use R454B refrigerant only. Do not attempt to mix in any other type of refrigerant.
For more details regarding R454B refrigerant, please visit our A2L Refrigerant Change Guide.
Do these units include refrigerant leak detection sensors, and if so, how do they work?
Equipment containing 64oz or more of refrigerant will be factory equipped with a leak detection sensor. Should this sensor detect a refrigerant leak, a fault will occur.
The unit controller will react by turning off the compressor and energize the blower which will dissipate the refrigerant.
I’ve noticed that the compressor is still running even though the Y-call has ended. Is this a problem?
No, this is perfectly normal and is a new function that adds the benefit of minimizing wear and tear on the compressor over time.
The UPM in all of our R-454B water source heat pump products includes a minimum compressor run time of five minutes.
If Y-call is removed, the compressor will remain energized until the five minutes have expired.
This wasn't the case with our legacy R-410A models, and therefore may be confusing to customers who are familiar with those products and now installing our new R-454B models.
The fan runs, but the compressor is not operating. The UPM board's LED is blinking THREE times. What should be checked?
This indicates that a "Condenser Freeze Condition" has been detected.
A condenser freeze may only occur in heating mode when the water coil is now on the low pressure side of the refrigeration operation.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
1. Low (or no) Water Flow Through The Coil
- Check water valves and pumps for correct operation.
- Check for blockage in the water coil.
2. Low Water Temperature
- Check the water temperature, is it below 40º entering?
- Is the heat pump connected to a closed loop with antifreeze?
- If so, check that the "FREEZE 1" resistor on the UPM board has been cut to set the unit to antifreeze mode.
3. Low Refrigerant
- Check refrigerant pressure with your gauge set.
4. Poor Water Heat Exchange
- Check for scaled water coil.
For full details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page.
The fan runs, but the compressor is not operating. The UPM board's LED is blinking FOUR times. What should be checked?
This indicates that a "Condensate Overflow Fault" has been detected.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
1. Poor Condensate Drainage
- Check the condensate pan to see if the water level is high.
- Check the drain line and pan for blockages, inadequate trapping, or double-trapping.
2. Blocked Return Air
- Check air filter for clogging.
- Check return air duct for blockages.
- In free-return applications, check that there is adequate space between the return air opening and walls (or other obstructions).
For full details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page.
The fan runs, but the compressor is not operating. The UPM board's LED is blinking SIX times. What should be checked?
This indicates that an "Evaporator Freeze Condition" has been detected.
An evaporator freeze may only occur in cooling mode when the air coil is now on the low pressure side of the refrigeration operation.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
1. Freeze Fault, Air Coil - No (Or Low) Air Flow
- Check fan motor for correct operation.
- Check air filter for clogging.
- Inspect air coil for dirt or debris clogging.
- Check duct work for obstructions (including if dampers are closed or blocked).
2. Freeze Fault, Air Coil - Blocked Return Air
- In free-return applications, check that there is adequate space between the return air opening and walls (or other obstructions).
3. Freeze Fault, Air Coil - Low Refrigerant
- Check refrigerant pressure with your gauge set.
For full details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page.
The fan runs, but the compressor is not operating. The UPM board's LED is blinking SEVEN times. What should be checked?
This indicates that the built-in sensor system may have detected a refrigerant leak inside the heat pump.
In this event, the on-board UPM board will shut down the compressor and run the blower to reduce the levels of built-up refrigerant inside the air in the cabinet to below 15% LFL. If you cycle the power to the unit off and back on after that point the compressor will turn back on and the heat pump will operate normally.
If the problem occurs again though we recommend turning the power to the product off and having a professional who is trained to work with R-454B refrigerant inspect the product to identify if a leak is truly present and to address it.
Once the leak has been resolved it's critical to use ONLY R-454B refrigerant to replace any that was lost from the system.
For full details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page.
The fan runs, but the compressor is not operating. There are NO blinks on the UPM board's LED.
When operating, there will of course be audible sounds coming from the unit itself, or even from the air ducts and water piping in your property.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
Air Flow Noise
1. Poor Air Duct And/Or Grille Design
- Ensure that all ductwork and grilles are correctly sized for the unit's air flow.
- Check for blockages or damage to the air ducts and grilles.
2. Fan Speed Setting Too High
- Consult the blower performance table in the product manual.
Structural Noise
1. Unit Not Mounted On A Full Anti-Vibration Pad
- Mount the unit on a suitable anti-vibration pad.
2. Unit Has Been Connected With Solid Installation Hardware Instead Of Flexible Hardware.
- All electrical conduit, water lines, and duct work connection to the unit should be flexible, as this will help prevent noises and vibrations from being transferred from the unit to the structure. Please refer to the manual for correct installation guidelines.
3. The Unit Is Physically Touching A Wall Or Other Part Of The Building
- Adjust the unit's mounting location to avoid physical contact with any part of the building's structure.
Compressor Noise
1. Elevated Head Pressure Caused By High Water Temperature Or Low Water Flow Rate (in cooling mode)
- If possible, reduce the water temperature or increase the water flow rate.
2. Scaled Or Dirty Water Coil
- Descale and clean the water coil.
3. Elevated Head Pressure Caused By Low Air Flow (in heating mode)
- Check the air filter for clogging.
- Check the duct work for blockages or damage.
- Increase the fan speed.
Water Hammer
1. Fast closing valves were used when installing the unit.
- Replace the fast closing valves with a slow-close type instead.
I hear noises when the heat pump Is running. What could they be, and can I reduce them?
When operating, there will of course be audible sounds coming from the unit itself, or even from the air ducts and water piping in your property.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
Air Flow Noise
1. Poor Air Duct And/Or Grille Design
- Ensure that all ductwork and grilles are correctly sized for the unit's air flow.
- Check for blockages or damage to the air ducts and grilles.
2. Fan Speed Setting Too High
- Consult the blower performance table in the product manual.
Structural Noise
1. Unit Not Mounted On A Full Anti-Vibration Pad
- Mount the unit on a suitable anti-vibration pad.
2. Unit Has Been Connected With Solid Installation Hardware Instead Of Flexible Hardware.
- All electrical conduit, water lines, and duct work connection to the unit should be flexible, as this will help prevent noises and vibrations from being transferred from the unit to the structure. Please refer to the manual for correct installation guidelines.
3. The Unit Is Physically Touching A Wall Or Other Part Of The Building
- Adjust the unit's mounting location to avoid physical contact with any part of the building's structure.
Compressor Noise
1. Elevated Head Pressure Caused By High Water Temperature Or Low Water Flow Rate (in cooling mode)
- If possible, reduce the water temperature or increase the water flow rate.
2. Scaled Or Dirty Water Coil
- Descale and clean the water coil.
3. Elevated Head Pressure Caused By Low Air Flow (in heating mode)
- Check the air filter for clogging.
- Check the duct work for blockages or damage.
- Increase the fan speed.
Water Hammer
1. Fast closing valves were used when installing the unit.
- Replace the fast closing valves with a slow-close type instead.
Can the heat pump's fan speed be adjusted?
There are multiple motor types that are available when the customer is selecting the specifications for the RL heat pump, and all but one of them do offer fan speed adjustment (the 575v PSC motor option is single-speed only).
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
For fan speed adjustment details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page
Are there water quality requirements that must be followed?
Yes.
Please refer to this service bulletin (PDF 0.1 MB) for a description of the water quality requirements for our water source heat pump products.
Can the water coil be acid cleaned?
Yes.
Please refer to this service bulletin (PDF 0.2 MB) for further details of how to clean the water coil.
CF Models
If I ever have to adjust the refrigerant levels in this product, is it ok to use R410A?
No.
This product is designed and approved to use R454B refrigerant only. Do not attempt to mix in any other type of refrigerant.
For more details regarding R454B refrigerant, please visit our A2L Refrigerant Change Guide.
Do these units include refrigerant leak detection sensors, and if so, how do they work?
Equipment containing 64oz or more of refrigerant will be factory equipped with a leak detection sensor. Should this sensor detect a refrigerant leak, a fault will occur.
The unit controller will react by turning off the compressor and energize the blower which will dissipate the refrigerant.
I’ve noticed that the compressor is still running even though the Y-call has ended. Is this a problem?
No, this is perfectly normal and is a new function that adds the benefit of minimizing wear and tear on the compressor over time.
The UPM in all of our R-454B water source heat pump products includes a minimum compressor run time of five minutes.
If Y-call is removed, the compressor will remain energized until the five minutes have expired.
This wasn't the case with our legacy R-410A models, and therefore may be confusing to customers who are familiar with those products and now installing our new R-454B models.
The fan runs, but the compressor is not operating. The UPM board's LED is blinking THREE times. What should be checked?
This indicates that a "Condenser Freeze Condition" has been detected.
A condenser freeze may only occur in heating mode when the water coil is now on the low pressure side of the refrigeration operation.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
1. Low (or no) Water Flow Through The Coil
- Check water valves and pumps for correct operation.
- Check for blockage in the water coil.
2. Low Water Temperature
- Check the water temperature, is it below 40º entering?
- Is the heat pump connected to a closed loop with antifreeze?
- If so, check that the "FREEZE 1" resistor on the UPM board has been cut to set the unit to antifreeze mode.
3. Low Refrigerant
- Check refrigerant pressure with your gauge set.
4. Poor Water Heat Exchange
- Check for scaled water coil.
For full details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page.
The fan runs, but the compressor is not operating. The UPM board's LED is blinking FOUR times. What should be checked?
This indicates that a "Condensate Overflow Fault" has been detected.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
1. Poor Condensate Drainage
- Check the condensate pan to see if the water level is high.
- Check the drain line and pan for blockages, inadequate trapping, or double-trapping.
2. Blocked Return Air
- Check air filter for clogging.
- Check return air duct for blockages.
- In free-return applications, check that there is adequate space between the return air opening and walls (or other obstructions).
For full details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page.
The fan runs, but the compressor is not operating. The UPM board's LED is blinking SIX times. What should be checked?
This indicates that an "Evaporator Freeze Condition" has been detected.
An evaporator freeze may only occur in cooling mode when the air coil is now on the low pressure side of the refrigeration operation.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
1. Freeze Fault, Air Coil - No (Or Low) Air Flow
- Check fan motor for correct operation.
- Check air filter for clogging.
- Inspect air coil for dirt or debris clogging.
- Check duct work for obstructions (including if dampers are closed or blocked).
2. Freeze Fault, Air Coil - Blocked Return Air
- In free-return applications, check that there is adequate space between the return air opening and walls (or other obstructions).
3. Freeze Fault, Air Coil - Low Refrigerant
- Check refrigerant pressure with your gauge set.
For full details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page.
The fan runs, but the compressor is not operating. The UPM board's LED is blinking SEVEN times. What should be checked?
This indicates that the built-in sensor system may have detected a refrigerant leak inside the heat pump.
In this event, the on-board UPM board will shut down the compressor and run the blower to reduce the levels of built-up refrigerant inside the air in the cabinet to below 15% LFL. If you cycle the power to the unit off and back on after that point the compressor will turn back on and the heat pump will operate normally.
If the problem occurs again though we recommend turning the power to the product off and having a professional who is trained to work with R-454B refrigerant inspect the product to identify if a leak is truly present and to address it.
Once the leak has been resolved it's critical to use ONLY R-454B refrigerant to replace any that was lost from the system.
For full details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page.
The fan runs, but the compressor is not operating. There are NO blinks on the UPM board's LED.
When operating, there will of course be audible sounds coming from the unit itself, or even from the air ducts and water piping in your property.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
Air Flow Noise
1. Poor Air Duct And/Or Grille Design
- Ensure that all ductwork and grilles are correctly sized for the unit's air flow.
- Check for blockages or damage to the air ducts and grilles.
2. Fan Speed Setting Too High
- Consult the blower performance table in the product manual.
Structural Noise
1. Unit Not Mounted On A Full Anti-Vibration Pad
- Mount the unit on a suitable anti-vibration pad.
2. Unit Has Been Connected With Solid Installation Hardware Instead Of Flexible Hardware.
- All electrical conduit, water lines, and duct work connection to the unit should be flexible, as this will help prevent noises and vibrations from being transferred from the unit to the structure. Please refer to the manual for correct installation guidelines.
3. The Unit Is Physically Touching A Wall Or Other Part Of The Building
- Adjust the unit's mounting location to avoid physical contact with any part of the building's structure.
Compressor Noise
1. Elevated Head Pressure Caused By High Water Temperature Or Low Water Flow Rate (in cooling mode)
- If possible, reduce the water temperature or increase the water flow rate.
2. Scaled Or Dirty Water Coil
- Descale and clean the water coil.
3. Elevated Head Pressure Caused By Low Air Flow (in heating mode)
- Check the air filter for clogging.
- Check the duct work for blockages or damage.
- Increase the fan speed.
Water Hammer
1. Fast closing valves were used when installing the unit.
- Replace the fast closing valves with a slow-close type instead.
I hear noises when the heat pump Is running. What could they be, and can I reduce them?
When operating, there will of course be audible sounds coming from the unit itself, or even from the air ducts and water piping in your property.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
Air Flow Noise
1. Poor Air Duct And/Or Grille Design
- Ensure that all ductwork and grilles are correctly sized for the unit's air flow.
- Check for blockages or damage to the air ducts and grilles.
2. Fan Speed Setting Too High
- Consult the blower performance table in the product manual.
Structural Noise
1. Unit Not Mounted On A Full Anti-Vibration Pad
- Mount the unit on a suitable anti-vibration pad.
2. Unit Has Been Connected With Solid Installation Hardware Instead Of Flexible Hardware.
- All electrical conduit, water lines, and duct work connection to the unit should be flexible, as this will help prevent noises and vibrations from being transferred from the unit to the structure. Please refer to the manual for correct installation guidelines.
3. The Unit Is Physically Touching A Wall Or Other Part Of The Building
- Adjust the unit's mounting location to avoid physical contact with any part of the building's structure.
Compressor Noise
1. Elevated Head Pressure Caused By High Water Temperature Or Low Water Flow Rate (in cooling mode)
- If possible, reduce the water temperature or increase the water flow rate.
2. Scaled Or Dirty Water Coil
- Descale and clean the water coil.
3. Elevated Head Pressure Caused By Low Air Flow (in heating mode)
- Check the air filter for clogging.
- Check the duct work for blockages or damage.
- Increase the fan speed.
Water Hammer
1. Fast closing valves were used when installing the unit.
- Replace the fast closing valves with a slow-close type instead.
Can the heat pump's fan speed be adjusted?
There are multiple motor types that are available when the customer is selecting the specifications for the CF heat pump, and all but one of them do offer fan speed adjustment (the 575v PSC motor option is single-speed only).
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
For fan speed adjustment details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page
Are there water quality requirements that must be followed?
Yes.
Please refer to this service bulletin (PDF 0.1 MB) for a description of the water quality requirements for our water source heat pump products.
Can the water coil be acid cleaned?
Yes.
Please refer to this service bulletin (PDF 0.2 MB) for further details of how to clean the water coil.
RL Models
If I ever have to adjust the refrigerant levels in this product, is it ok to use R410A?
No.
This product is designed and approved to use R454B refrigerant only. Do not attempt to mix in any other type of refrigerant.
For more details regarding R454B refrigerant, please visit our A2L Refrigerant Change Guide.
Do these units include refrigerant leak detection sensors, and if so, how do they work?
Equipment containing 64oz or more of refrigerant will be factory equipped with a leak detection sensor. Should this sensor detect a refrigerant leak, a fault will occur.
The unit controller will react by turning off the compressor and energize the blower which will dissipate the refrigerant
I’ve noticed that the compressor is still running even though the Y-call has ended. Is this a problem?
No, this is perfectly normal and is a new function that adds the benefit of minimizing wear and tear on the compressor over time.
The UPM in all of our R-454B water source heat pump products includes a minimum compressor run time of five minutes.
If Y-call is removed, the compressor will remain energized until the five minutes have expired.
This wasn't the case with our legacy R-410A models, and therefore may be confusing to customers who are familiar with those products and now installing our new R-454B models.
The fan runs, but the compressor is not operating. The UPM board's LED is blinking THREE times. What should be checked?
This indicates that a "Condenser Freeze Condition" has been detected.
A condenser freeze may only occur in heating mode when the water coil is now on the low pressure side of the refrigeration operation.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
1. Low (or no) Water Flow Through The Coil
- Check water valves and pumps for correct operation.
- Check for blockage in the water coil.
2. Low Water Temperature
- Check the water temperature, is it below 40º entering?
- Is the heat pump connected to a closed loop with antifreeze?
- If so, check that the "FREEZE 1" resistor on the UPM board has been cut to set the unit to antifreeze mode.
3. Low Refrigerant
- Check refrigerant pressure with your gauge set.
4. Poor Water Heat Exchange
- Check for scaled water coil.
For full details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page.
The fan runs, but the compressor is not operating. The UPM board's LED is blinking FOUR times. What should be checked?
This indicates that a "Condensate Overflow Fault" has been detected.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
1. Poor Condensate Drainage
- Check the condensate pan to see if the water level is high.
- Check the drain line and pan for blockages, inadequate trapping, or double-trapping.
2. Blocked Return Air
- Check air filter for clogging.
- Check return air duct for blockages.
- In free-return applications, check that there is adequate space between the return air opening and walls (or other obstructions).
For full details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page.
The fan runs, but the compressor is not operating. The UPM board's LED is blinking SIX times. What should be checked?
This indicates that an "Evaporator Freeze Condition" has been detected.
An evaporator freeze may only occur in cooling mode when the air coil is now on the low pressure side of the refrigeration operation.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
1. Freeze Fault, Air Coil - No (Or Low) Air Flow
- Check fan motor for correct operation.
- Check air filter for clogging.
- Inspect air coil for dirt or debris clogging.
- Check duct work for obstructions (including if dampers are closed or blocked).
2. Freeze Fault, Air Coil - Blocked Return Air
- In free-return applications, check that there is adequate space between the return air opening and walls (or other obstructions).
3. Freeze Fault, Air Coil - Low Refrigerant
- Check refrigerant pressure with your gauge set.
For full details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page.
The fan runs, but the compressor is not operating. The UPM board's LED is blinking SEVEN times. What should be checked?
This indicates that the built-in sensor system may have detected a refrigerant leak inside the heat pump.
In this event, the on-board UPM board will shut down the compressor and run the blower to reduce the levels of built-up refrigerant inside the air in the cabinet to below 15% LFL. If you cycle the power to the unit off and back on after that point the compressor will turn back on and the heat pump will operate normally.
If the problem occurs again though we recommend turning the power to the product off and having a professional who is trained to work with R-454B refrigerant inspect the product to identify if a leak is truly present and to address it.
Once the leak has been resolved it's critical to use ONLY R-454B refrigerant to replace any that was lost from the system.
For full details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page.
The fan runs, but the compressor is not operating. There are NO blinks on the UPM board's LED.
When operating, there will of course be audible sounds coming from the unit itself, or even from the air ducts and water piping in your property.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
Air Flow Noise
1. Poor Air Duct And/Or Grille Design
- Ensure that all ductwork and grilles are correctly sized for the unit's air flow.
- Check for blockages or damage to the air ducts and grilles.
2. Fan Speed Setting Too High
- Consult the blower performance table in the product manual.
Structural Noise
1. Unit Not Mounted On A Full Anti-Vibration Pad
- Mount the unit on a suitable anti-vibration pad.
2. Unit Has Been Connected With Solid Installation Hardware Instead Of Flexible Hardware.
- All electrical conduit, water lines, and duct work connection to the unit should be flexible, as this will help prevent noises and vibrations from being transferred from the unit to the structure. Please refer to the manual for correct installation guidelines.
3. The Unit Is Physically Touching A Wall Or Other Part Of The Building
- Adjust the unit's mounting location to avoid physical contact with any part of the building's structure.
Compressor Noise
1. Elevated Head Pressure Caused By High Water Temperature Or Low Water Flow Rate (in cooling mode)
- If possible, reduce the water temperature or increase the water flow rate.
2. Scaled Or Dirty Water Coil
- Descale and clean the water coil.
3. Elevated Head Pressure Caused By Low Air Flow (in heating mode)
- Check the air filter for clogging.
- Check the duct work for blockages or damage.
- Increase the fan speed.
Water Hammer
1. Fast closing valves were used when installing the unit.
- Replace the fast closing valves with a slow-close type instead.
Can the heat pump's fan speed be adjusted?
There are multiple motor types that are available when the customer is selecting the specifications for the RL heat pump, and all but one of them do offer fan speed adjustment (the 575v PSC motor option is single-speed only).
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
For fan speed adjustment details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page
Are there water quality requirements that must be followed?
Yes.
Please refer to this service bulletin (PDF 0.1 MB) for a description of the water quality requirements for our water source heat pump products.
Can the water coil be acid cleaned?
Yes.
Please refer to this service bulletin (PDF 0.2 MB) for further details of how to clean the water coil.
CL Models
If I ever have to adjust the refrigerant levels in this product, is it ok to use R410A?
No.
This product is designed and approved to use R454B refrigerant only. Do not attempt to mix in any other type of refrigerant.
For more details regarding R454B refrigerant, please visit our A2L Refrigerant Change Guide.
Do these units include refrigerant leak detection sensors, and if so, how do they work?
Equipment containing 64oz or more of refrigerant will be factory equipped with a leak detection sensor. Should this sensor detect a refrigerant leak, a fault will occur.
The unit controller will react by turning off the compressor and energize the blower which will dissipate the refrigerant.
I’ve noticed that the compressor is still running even though the Y-call has ended. Is this a problem?
No, this is perfectly normal and is a new function that adds the benefit of minimizing wear and tear on the compressor over time.
The UPM in all of our R-454B water source heat pump products includes a minimum compressor run time of five minutes.
If Y-call is removed, the compressor will remain energized until the five minutes have expired.
This wasn't the case with our legacy R-410A models, and therefore may be confusing to customers who are familiar with those products and now installing our new R-454B models.
The fan runs, but the compressor is not operating. The UPM board's LED is blinking THREE times. What should be checked?
This indicates that a "Condenser Freeze Condition" has been detected.
A condenser freeze may only occur in heating mode when the water coil is now on the low pressure side of the refrigeration operation.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
1. Low (or no) Water Flow Through The Coil
- Check water valves and pumps for correct operation.
- Check for blockage in the water coil.
2. Low Water Temperature
- Check the water temperature, is it below 40º entering?
- Is the heat pump connected to a closed loop with antifreeze?
- If so, check that the "FREEZE 1" resistor on the UPM board has been cut to set the unit to antifreeze mode.
3. Low Refrigerant
- Check refrigerant pressure with your gauge set.
4. Poor Water Heat Exchange
- Check for scaled water coil.
For full details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page.
The fan runs, but the compressor is not operating. The UPM board's LED is blinking FOUR times. What should be checked?
This indicates that a "Condensate Overflow Fault" has been detected.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
1. Poor Condensate Drainage
- Check the condensate pan to see if the water level is high.
- Check the drain line and pan for blockages, inadequate trapping, or double-trapping.
2. Blocked Return Air
- Check air filter for clogging.
- Check return air duct for blockages.
- In free-return applications, check that there is adequate space between the return air opening and walls (or other obstructions).
For full details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page.
The fan runs, but the compressor is not operating. The UPM board's LED is blinking SIX times. What should be checked?
This indicates that an "Evaporator Freeze Condition" has been detected.
An evaporator freeze may only occur in cooling mode when the air coil is now on the low pressure side of the refrigeration operation.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
1. Freeze Fault, Air Coil - No (Or Low) Air Flow
- Check fan motor for correct operation.
- Check air filter for clogging.
- Inspect air coil for dirt or debris clogging.
- Check duct work for obstructions (including if dampers are closed or blocked).
2. Freeze Fault, Air Coil - Blocked Return Air
- In free-return applications, check that there is adequate space between the return air opening and walls (or other obstructions).
3. Freeze Fault, Air Coil - Low Refrigerant
- Check refrigerant pressure with your gauge set.
For full details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page.
The fan runs, but the compressor is not operating. The UPM board's LED is blinking SEVEN times. What should be checked?
This indicates that the built-in sensor system may have detected a refrigerant leak inside the heat pump.
In this event, the on-board UPM board will shut down the compressor and run the blower to reduce the levels of built-up refrigerant inside the air in the cabinet to below 15% LFL. If you cycle the power to the unit off and back on after that point the compressor will turn back on and the heat pump will operate normally.
If the problem occurs again though we recommend turning the power to the product off and having a professional who is trained to work with R-454B refrigerant inspect the product to identify if a leak is truly present and to address it.
Once the leak has been resolved it's critical to use ONLY R-454B refrigerant to replace any that was lost from the system.
For full details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page.
The fan runs, but the compressor is not operating. There are NO blinks on the UPM board's LED.
When operating, there will of course be audible sounds coming from the unit itself, or even from the air ducts and water piping in your property.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
Air Flow Noise
1. Poor Air Duct And/Or Grille Design
- Ensure that all ductwork and grilles are correctly sized for the unit's air flow.
- Check for blockages or damage to the air ducts and grilles.
2. Fan Speed Setting Too High
- Consult the blower performance table in the product manual.
Structural Noise
1. Unit Not Mounted On A Full Anti-Vibration Pad
- Mount the unit on a suitable anti-vibration pad.
2. Unit Has Been Connected With Solid Installation Hardware Instead Of Flexible Hardware.
- All electrical conduit, water lines, and duct work connection to the unit should be flexible, as this will help prevent noises and vibrations from being transferred from the unit to the structure. Please refer to the manual for correct installation guidelines.
3. The Unit Is Physically Touching A Wall Or Other Part Of The Building
- Adjust the unit's mounting location to avoid physical contact with any part of the building's structure.
Compressor Noise
1. Elevated Head Pressure Caused By High Water Temperature Or Low Water Flow Rate (in cooling mode)
- If possible, reduce the water temperature or increase the water flow rate.
2. Scaled Or Dirty Water Coil
- Descale and clean the water coil.
3. Elevated Head Pressure Caused By Low Air Flow (in heating mode)
- Check the air filter for clogging.
- Check the duct work for blockages or damage.
- Increase the fan speed.
Water Hammer
1. Fast closing valves were used when installing the unit.
- Replace the fast closing valves with a slow-close type instead.
Can the heat pump's fan speed be adjusted?
There are multiple motor types that are available when the customer is selecting the specifications for the CL heat pump, and all but one of them do offer fan speed adjustment (the 575v PSC motor option is single-speed only).
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
For fan speed adjustment details, please refer to the installation manual that came with your product.
If you do not have the manual, one can be downloaded from this web page
Are there water quality requirements that must be followed?
Yes.
Please refer to this service bulletin (PDF 0.1 MB) for a description of the water quality requirements for our water source heat pump products.
Can the water coil be acid cleaned?
Yes.
Please refer to this service bulletin (PDF 0.2 MB) for further details of how to clean the water coil.
LV Models
I've heard that federal regulations have changed and that R410A refrigerant is being phased out. What is Bosch doing to accommodate the change?
Bosch Home Comfort is working on bringing new heat pumps products to the market that will use R-454B refrigerant instead of the existing R410A.
For more details and deadline dates, please visit our A2L Refrigerant Change Guide.
The fan runs, but the compressor is not operating. The UPM board's LED is blinking THREE times. What should be checked?
This indicates that a "Condenser Freeze Condition" has been detected.
A condenser freeze may only occur in heating mode when the water coil is now on the low pressure side of the refrigeration operation.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
For further details on all of the points below, please refer to the product's manual (available for download HERE).
1. Low (or no) Water Flow Through The Coil
a. Check water valves and pumps for correct operation.
b. Check for blockage in the water coil.
2. Low Water Temperature
a. Check the water temperature, is it below 40º entering?
b. Is the heat pump connected to a closed loop with antifreeze? If so, check that the "FREEZE 1" resistor on the UPM board has been cut to set the unit to antifreeze mode.
3. Low Refrigerant
a. Check refrigerant pressure with your gauge set.
4. Poor Water Heat Exchange
a. Check for scaled water coil.
The fan runs, but the compressor is not operating. The UPM board's LED is blinking FOUR times. What should be checked?
This indicates that a "Condensate Overflow Fault" has been detected.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
For further details on all of the points below, please refer to the product's manual (available for download HERE).
1. Poor Condensate Drainage
a. Check the condensate pan to see if the water level is high.
b. Check the drain line and pan for blockages, inadequate trapping, or double-trapping.
2. Blocked Return Air
a. Check air filter for clogging.
b. Check return air duct for blockages.
c. In free-return applications, check that there is adequate space between the return air opening and walls (or other obstructions).
The fan runs, but the compressor is not operating. The UPM board's LED is blinking SIX times. What should be checked?
This indicates that an "Evaporator Freeze Condition" has been detected.
An evaporator freeze may only occur in cooling mode when the air coil is now on the low pressure side of the refrigeration operation.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
For further details on all of the points below, please refer to the product's manual (available for download HERE).
1. Freeze Fault, Air Coil - No (Or Low) Air Flow
a. Check fan motor for correct operation.
b. Check air filter for clogging.
c. Inspect air coil for dirt or debris clogging.
d. Check duct work for obstructions (including if dampers are closed or blocked).
2. Freeze Fault, Air Coil - Blocked Return Air
a. In free-return applications, check that there is adequate space between the return air opening and walls (or other obstructions).
3. Freeze Fault, Air Coil - Low Refrigerant
a. Check refrigerant pressure with your gauge set.
The fan runs, but the compressor is not operating. There are NO blinks on the UPM board's LED.
This may indicate that the contactor is not energizing.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
For further details on all of the points below, please refer to the product's manual (available for download HERE).
1. Is The Thermostat Calling For Compressor To Operate And Is It Sending 24vac To The Heat Pump?
a. Ensure that thermostat is on and is calling for "Y".
b. Check "Y" connection from thermostat, and ensure that there is 24vac across "Y" and "C" terminals in heat pump when thermostat is calling.
2. Possible Loose Wire To Contactor Coil
a. Check wiring to ensure that there is 24vac across the contactor coil.
3. Potential Failed Contactor Coil
a. Test contactor with 24vac across "R" and "C".
b. Ohm out the contactor coil. Open circuit indicates that the coil has failed.
I hear noises when the heat pump Is running. What could they be, and can I reduce them?
When operating, there will of course be audible sounds coming from the unit itself, or even from the air ducts and water piping in your property.
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
For further details on all of the points below, please refer to the product's manual (available for download HERE).
Air Flow Noise;
1. Poor Air Duct And/Or Grille Design
a. Ensure that all ductwork and grilles are correctly sized for the unit's air flow.
b. Check for blockages or damage to the air ducts and grilles.
2. Fan Speed Setting Too High
a. Consult the blower performance table in the product manual.
Structural Noise
1. Unit Not Mounted On A Full Anti-Vibration Pad
a. Mount the unit on a suitable anti-vibration pad.
2. Unit Has Been Connected With Solid Installation Hardware Instead Of Flexible Hardware.
a. All electrical conduit, water lines, and duct work connection to the unit should be flexible, as this will help prevent noises and vibrations from being transferred from the unit to the structure. Please refer to the manual for correct installation guidelines.
3. The Unit Is Physically Touching A Wall Or Other Part Of The Building
a. Adjust the unit's mounting location to avoid physical contact with any part of the building's structure.
Compressor Noise
1. Elevated Head Pressure Caused By High Water Temperature Or Low Water Flow Rate (in cooling mode)
a. If possible, reduce the water temperature or increase the water flow rate.
2. Scaled Or Dirty Water Coil
a. Descale and clean the water coil.
3. Elevated Head Pressure Caused By Low Air Flow (in heating mode)
a. Check the air filter for clogging.
b. Check the duct work for blockages or damage.
c. Increase the fan speed.
Water Hammer
1. Fast closing valves were used when installing the unit.
a. Replace the fast closing valves with a slow-close type instead.
Can the heat pump's fan speed be adjusted?
There are multiple motor types that are available when the customer is selecting the specifications for the LV heat pump, and all but one of them do offer fan speed adjustment (the 575v PSC motor option is single-speed only).
Safety Notice - This is a high voltage product and contains refrigerant. Only professionals who are qualified to work on such equipment should do so.
For fan speed adjustment details, please refer to the product's manual (available for download HERE).
Are there water quality requirements that must be followed?
Yes.
Please refer to this service bulletin for a description of the water quality requirements for our water source heat pump products; LINK
Can the water coil be acid cleaned?
Yes.
Please refer to this service bulletin for further details of how to clean the water coil; LINK
SM Rev. C Models
I've heard that federal regulations have changed and that R410A refrigerant is being phased out. What is Bosch doing to accommodate the change?
Bosch Home Comfort is working on bringing new heat pumps products to the market that will use R-454B refrigerant instead of the existing R410A.
For more details and deadline dates, please visit our A2L Refrigerant Change Guide.
What platforms and operating systems are compatible with the Bosch EasyStart app?
The EasyStart app is compatible with Windows PCs and Android/iOS tablets.
Minimum device requirements;
- PC - Windows 7 & 10.
- Android Tablets - Android 4.1 and above.
- Apple Tablets - iOS 11.4 and above (iOS 12.0 is recommended).
For full details, please refer to the EasyStart manual that came supplied with the product.
If you no longer have a copy of the manual, a digital version can be downloaded from this page.
Is the EasyStart app compatible with cellphones?
The EasyStart app is not designed for use with cellphones. It requires a Windows PC or Android/iOS tablet.
For full details, please refer to the EasyStart manual that came supplied with the product.
If you no longer have a copy of the manual, a digital version can be downloaded from this page.
The heat pump appears to be running and the temperature in the home is as expected, but the humidity seems too high. What could be the issue?
There are a number of reasons why the home's humidity could be too high even though the temperature has been controlled adequately;
- The air flow is too high - Consult the blower performance table in the product's manual and reduce the fan speed accordingly.
- Low refrigerant - Use your gauge set and check the refrigerant pressures.
- Short-cycling -
- Unit oversized for the application - Check the unit's performance ratings against the building load calculation results. It is critical that a correctly sized heat pump be used to ensure correct operation.
- Poor thermostat location - Make sure that the thermostat is not located near a supply air duct.
For full details and troubleshooting steps, please refer to the manual that came supplied with the product.
If you no longer have a copy of the manual, a digital version can be downloaded from this page.