Gas Tankless Water Heaters FAQ

This is a perception that is most commonly noted by owners that have recently switched to a combi-boiler or a tankless water heater after moving away from using a heated storage tank to produce and store Domestic Hot Water (DHW).

Here's why:

Heated Storage Tanks - The water contained in such a water heater is being heated throughout the day and night, regardless of whether you are using it or not.

The benefit of course, is that the stored water is already hot and ready for use at any time.

However, that means that energy is being used just to keep a large supply of hot water on standby. You are paying to heat and store water all the time, just to use it sporadically through the day.

In addition to the ongoing energy use, you will also only be able to use as much hot water as the tank can store, and once the hot water is depleted, you will need to wait until the fresh cold water has been heated up and ready to use.

Combi-Boilers & Tankless Water Heaters - These types of water heating products only produce hot water when the owner opens a hot fixture somewhere in the home.

This means that no hot water is stored in the product, and so when you open a fixture in the home the water heater will ignite and then start heating the cold water that is flowing through its heat exchanger now. That does mean that there is a small delay in the delivery of hot water to the fixture, and if you previously used a heated storage tank you may notice it.

The benefits though, are significant:

• You are only paying for energy while the product is activated and producing hot water on-demand. When you close the hot water fixture, the product is going to shut down and go back into standby mode.
• You are not limited to a fixed amount of hot water that will deplete and then run cold. As long as you have a hot water fixture open and the product has activated, you will have endless hot water from that fixture until you close it.

Plumbing Distance:

Regardless of whether you are using a heated storage tank, a combi-boiler, or a tankless water heater to produce your home's hot water, there is another delay that must be recognized.

There will still be a delay in the delivery of hot water as the plumbing between the product and the fixtures will contain cold water that will need to be pushed ahead of the hot water that's heading towards the open fixture.

Simply put: The longer the run of plumbing, the longer it will take for the hot water to arrive where it's needed.

Potential Solutions

For the majority of users, the small delay in hot water being produced and then reaching their hot fixtures is of no concern. It is a normal dynamic of hot water that is produced by a combi-boiler or a tankless water heater, and the owner is instead focused on enjoying the lower energy costs!

• If you have a fixture that is particularly far away from the water heating product, and it's one that you frequently use and the delay is problematic for you, then you could use an electric mini-tank water heater as booster. These water heaters are typically 120v and should be installed close to the distant hot fixture and in-line between the main water heating product and the distant fixture. For further details regarding our family of Tronic 3000T electric mini-tank water heaters, please visit this page.

• If you would prefer to reduce the wait time for hot water at all hot fixtures in the home, then we recommend consulting a licensed plumber to discuss the options for installing a recirculating hot water plumbing arrangement. Please visit this page to search for a contractor in your area. Typically one loop of hot water plumbing will leave the water heating product, travel around the home, and then back to the product. Short plumbing lines to each hot water fixture will then branch off the main loop. A pump and a timer will be used to circulate the water around that loop occasionally, which will also activate the combi-boiler or tankless water heater, and leave hot water in the plumbing loop around the home. The next time you open a hot water fixture, you will have less of a wait time for cold water to flush through, as it is pre-heated from the last time that the recirculation pump ran.
  Important! Before deciding to install a recirculation loop, be certain that your combi-boiler or tankless water heater can safely be installed in such an application. Some models are designed to be supplied with cold water only and may be damaged if supplied with heated water that is returning from a circulation loop. Consult the literature that came supplied with your product. If you no longer have the printed literature that came supplied with your product, an electronic copy can be downloaded from our manuals download page.

Safety Notice - This is a gas-fired water heater. Only professionals who are qualified to work on such equipment should do so!

If you are in need of a qualified professional in your area, please use this contractor search page

As with all water heating equipment, there are maintenance requirements that must be carried out annually.

The following list is a general overview of the required annual maintenance points, and as such may not cover all steps that are required for your specific model.

• Inspect exhaust venting and air intake piping for blockages or damage.

• Inspect heat exchanger for soot, water leaks, or compromised seals.

• Inspect burner for damage or blockages (see video below)

• Inspect the pressure relief valve for leaks and test for correct operation.

• Inspect and clean the inlet water filter.

• Inspect the condensate trap for leaks, blockages, or damage.

• Inspect and clean the air filter that is mounted on the front of the fan.

• Descale the heat exchanger (especially in areas with high mineral content in the water).

For full maintenance instructions, please refer to the installation manual for your specific model. You can download a copy of the manual from the links at the bottom of this page.

No, the product can only be connected to a 2.4Ghz wireless network and will not make a connection to 5Ghz networks.

Many modern Wifi routers use both 2.4Ghz and 5Ghz channels automatically with no input from the user, so if you are having difficulty in connecting your Wifi-enabled Greentherm 9000 to your home's Wifi network, it could be the case that your router is trying to connect it to the 5Ghz channel instead of the 2.4Ghz channel.

You may be able to go into the settings in your router and setup a dedicated 2.4Ghz Wifi network*, and once that's done you can then connect your Wifi-enabled Greentherm 9000 to it.

*If you are unsure of your Wifi network details and how to manage them, please consult the manufacturer of your specific Wifi router for further details.

There are two models of WiFi gateway modules that have been used in the Greentherm 9000 products since they were released, and the app that is needed to connect to them will depend on which module you have installed. The gateway module is located on the inside of the water heater's front cover immediately behind the display.

Before removing the front cover, please unplug the water heater's power cord from the power outlet that you have it plugged into.

How To Identify An Original (now discontinued) WiFi Gateway Module

Look for the white label on the WiFi module, and observe the following:

• The name "Bosch" in the top-left of the label has no other letters or numbers next to it
• The long serial number at the very bottom of the label will end with 944
• There is a group of three QR codes on the right-side of the label

Correct App To Use - "Bosch Water" App

• Android App Store Link
• Apple iOS Store Link

How To Identify A Current-Version "Connect-Key" WiFi Gateway Module

Look for the white label on the WiFi module, and observe the following:

• The name "Bosch" in the top-left of the label has the characters "G10-3W" next to it
• The long serial number at the very bottom of the label will end with 318
• There are two QR codes on the right-side of the label, and two QR codes on the left of the label

Correct App To Use - "HomeCom Easy" App

• Android App Store Link
• Apple iOS Store Link

No.

The connectivity hardware (where installed) on all Greentherm 9000 products is not compatible with the Bosch EasyAir app.

For details on which correct app to use, please view the FAQ topic above.

The "Connect-Key" WiFi gateway module is indeed backwards compatible with the following Greentherm 9000 water heater models* and can be installed to replace an older module that has failed:

• T9900i SE 199
• T9900 SE 160
• T9900 SE 199
• T9800 SE 160
• T9800 SE 199

The new module is not compatible with the "Bosch Water" app that was used with the discontinued Wifi module.

If you are replacing the older WiFi module with a new "Connect-Key" Wifi module, then you must switch to the "HomeCom Easy" app to regain connectivity.

*Please note that the following two Greentherm 9000 models have no WiFi compatibility, regardless of WiFi module type:

• T9800 SEO 160
• T9800 SEO 199

"Auto Tuning" is the system that is built-in to the Greentherm 9000 water heater that enables it to attempt to optimize the air/fuel mixture itself with no physical adjustments needed to be performed by the user.

As with all fossil-fueled equipment, there is an optimal mixture of air and fuel that will achieve the best possible combustion. That optimal mix will depend on many variables; Including (but not limited to) fuel type and quality, altitude, and air quality.

Historically it has typically required a trained gas technician to use a combustion analyzer to be able to safely and correctly carry out an air/fuel calibration, but the Greentherm 9000's ability to attempt to calibrate itself is an excellent step forward in our tankless product technology.

When Should An Auto Tuning Be Carried Out?

• When the installation of the water heater has been completed, and it is being commissioned and put into operation for the first time.

• If the fan, control unit, or gas valve have been replaced.

• If the gas type is being converted from NG to LP.

• If repeated combustion errors are being experienced.

For directions on how to initiate the auto-tuning, please refer to the video below.

In addition, please refer to the installation manual for your specific model. You can download a copy of the manual from the links at the bottom of this page

The AD code is not an error code, it is an informational code.

If it appears on the display screen it is letting you know that the maximum power output of the water heater has been derated. This means that the unit will still work and produce hot water, but at a reduced capacity.

There are a number of potential causes for this to happen, including;

• Air supply to the water heater is insufficient.
• Blockage in the air intake or exhaust piping.
• Water heater installed at an elevation over 2,000ft.
• Total equivalent length of the air intake and exhaust piping being too long (too many elbows can be a common factor in this).
• Incorrect exhaust pipe termination.
• Clogged air filter (if equipped) on the blower motor.

Please refer to the installation manual to check the above points, and ensure that all aspects of the intake and exhaust piping is in accordance with the installation requirements. Also verify that no blockages are present.

If you no longer have the printed manual that came supplied with your product, an electronic copy can be downloaded from our Manuals download page here.

Safety Notice - This is a gas-fired water heater. Only professionals who are qualified to work on such equipment should do so!

If you are in need of a qualified professional in your area, please use this contractor search page

These codes can either be an indicator that the burner could be becoming clogged with dust, pollen, debris, or insects (especially if the air intake entry on the exterior of the property is in an area that is prone to those things), or that a blockage may be present in the exhaust venting or air intake piping.

We recommend that you view this product information notice (PDF 0.2 MB) for further details regarding clogged burners and preventative steps.

Please visit this page for online tools that will allow you to search for part numbers, pricing, and availability.

An air filter can be purchased (if one is not installed already*);

• P/N 8738725270 - Pleated paper filter, offers protection from all types of contaminants in the air.

*Initially, the Greentherm 9000 water heater models did not have an air filter installed from the factory. This was changed during the production history though, and your unit may have either a pleated paper filter or a metal mesh screen already installed on the fan motor's air inlet inside the cabinet. If you have no air filter at all, or you have the metal mesh screen, we recommend that you purchase and install the pleated paper filter instead for maximum protection.

For filter installation instructions, please see the video below.

You can indeed, and we recommend using the "Schedule" instead of the "Always Active" recirculation control option as a way to optimize energy usage.

For details of how to create a customized schedule, and for details of recirculation application design, please refer to the installation manual for your specific model. You can download a copy of the manual from the links at the bottom of this page

Yes, as with all such products there are certain actions that must be taken at regular intervals to ensure that the water heater remains working in a safe and efficient manner while also minimizing the chance of a component failure. Full details regarding the maintenance requirements of this product can be found in the printed manual that can supplied with the water heater, and so please have it to hand when conducting any maintenance steps. If you no longer have the manual, an electronic version can is availalbe for download on this page in the table titled Bosch Aquastar Models.

Safety Notice - This is a gas-fired product, and only professionals who are qualified to work on live gas equipment should do so.

Annual Maintenance

• Inspect Water Filter Screen - Located inside the cold water inlet port within the water valve is a water filter screen. The filter prevents solid particles in the water supply from entering the water valve and causing damage, and over time it does mean that the filter itself will begin to plug up. This will eventually reduce the water flow rate through the water heater, potentially resulting in water temperature issues or even prevent the water heater from activating.
• Once a year remove the filter screen and clean it under fresh running water. If lime scale is present in the filter we recommend soaking it in a little white vinegar until the scale dissolves. If the filter is visibly damaged, then it should be replaced immediately (refer to parts list (PDF 0.2 MB) for part#).

• Inspect Pilot Flame Assembly - The pilot flame should be blue and fully engulf the thermocouple. If the pilot flame appears to be unstable, or yellow, then the pilot orifice or the pilot tube may be dirty. Refer to the "Maintenance And Service" section of the product manual for directions on cleaning.
• Inspect Main Burners - When lit, the main burners should be blue and steady. If they are yellow or unstable this may be an indication that the burner orifices are clogged (typically with dust or even spider webs). We recommend that a qualified gas service person be used to clean the burners.
• Exhaust Vent System - Correct venting of the exhaust gases is essential for the correct and safe operation of the water heater. Shut off the gas and water supplies to the water heater and check the entire vent system for damage or blockages. The entire length of the vent must be clear and damage-free.

Every Two Years

• Lubricate The Water Valve - The gas valve is operated by a mechanical connection to the water valve. There is a pushrod inside the top of the water valve, and it should be lubricated with silicon grease every two years to ensure that it slides back and forth through the o-rings correctly. If this is not done then over time you will likely see a reduced operation of the water valve, which turn will reduce the output of the gas valve and burners and the output water temperature will not rise as much as it did when the water heater was new.

If the pushrod jams completely due to lack of maintenance you could also experience the following two major symptoms:

• When you use a hot faucet to call for hot water, the burners in the water heater may not activate at all.
• The burners could ignite correctly on a call for hot water, but they may stay lit AFTER the call for hot water has stopped. If this happens, shut the gas control slider to the Off position immediately!

As you can see from the above description, correct maintenance of the water valve is absolutely essential to the safe and correct operation of the water heater.

Every Three To Five Years

• Rebuild the water valve - The duration in which this is needed will vary based on quality and chemistry of the water supplied to the product, but we do recommend that it is carried out every three to five years. It involves purchasing and installing a new pushrod and o-rings for the water valve.
• Important Note! If the water valve has been installed for longer than five years and has never been serviced, it may be prudent to skip the cleaning/rebuild altogether and instead purchase a new water valve assembly. A universal water valve kit (part# 8707002499) is available that is compatible with all versions and production ages of the 125B water heater.

Additional Maintenance Tip – Limescale

Heat Exchanger - Over time it may be possible that limescale builds up inside the water tubing of the heat exchanger. The likelihood of it happening will of course be dependent on the chemistry of the water that is supplied to the water heater and the temperature at which the product is set to. To combat the build-up of scale we recommend the following procedure be carried out annually;

• Turn off the gas supply to the water heater, and also slide the gas control knob on the water heater to the Off position.
• Close the water supply valve to the water heater.
• Open up a hot water fixture in the house to relieve the pressure.
• Place a bucket under the plumbing connections to and from the water heater to catch any remaining water, and remove the connections.
• Once the water has finished draining, you will need to setup a submersible pump in a bucket of white vinegar and use hoses to circulate the vinegar through the water heater. If this process is done annually then you may need to circulate the vinegar for a few minutes, but if it's been a number of years, or if scale is a problem in your location, then it may be prudent to circulate the vinegar for half an hour.
• If the white vinegar that it returning back into the bucket is very cloudy, then pour it out and repeat the process with fresh white vinegar.
• When you have finished the white vinegar flushing, reconnect the water connections to and from the water heater, relight the pilot, and put the product back into operation.
• Open a hot water faucet to ensure that the water heater fires up and runs correctly, and leave the hot water flowing for a few minutes to flush any white vinegar from the water heater.

Don't worry, you've received the correct part!

The existing water temperature limiter is screwed into a dry-well that's located in the outlet hot water pipe in the bottom left area of the water heater.

The replacement limiter shares the same part number (87072060400) and does the same job, but instead of screwing into the existing well it instead simply clamps onto the copper pipe immediately next to the well.

Refer to the instruction diagram sheet that came with the replacement limiter for further details.

For LP:

Static = 11" to 14" water column.

Operating = 10.5" minimum.

For NG:

Static = 7" to 14" water column.

Operating = 5.7" minimum.

Minimum = 18PSI

Maximum = 150PSI.

1.) Is the pilot flame lit and steady? If not, light the pilot.

2.) Is the water flowing at a high enough rate through the water heater?

• If the temperature control knob is turned all the way clockwise, the 125B requires an absolute minimum flow rate of 0.5gpm to activate the burners.
• If the temperature knob is rotated all the way counter-clockwise, the minimum flow rate needed to activate the burners rises to 1.1gpm.
• If the flow rate does not exceed the minimum required to activate the burners, they will not turn on. Look into increasing the flow rate from that fixture.

3.) If the pilot is lit and the burners are not activating despite the water flow rate being higher than the minimum required, you may have a crossover in the plumbing in the home somewhere (typically it could be anywhere where hot and cold water are blended together; such as shower valves, single-handled sink faucets, and even washing machines).

To check for a plumbing crossover, do the following:

• Turn the cold water supply to the water heater off (do NOT shut the water supply to the house off!).
• Go around the house and open all hot water faucets. Make certain that all single-handled faucets are set to HOT only.
• Wait for 5 minutes.
• Go around and check all of the outlets. Water should not be flowing from any of them (remember, you have shut off the water supply to the water heater, and as that feeds the home's hot water fixtures you should have no water flowing from them now).
• If you do find water flowing from any hot fixture while the water supply to the water heater is still turned off, then you have a plumbing a crossover somewhere in the home. A plumber should be called in to investigate and resolve it. A plumbing crossover can cause activation, and water temperature stability issues, with any tankless water heater.

4.) If there is no plumbing crossover but the burners will still not activate with sufficient water flow, then you may be looking at a dirty, or jammed, pushrod in the water valve. Please refer to the "Regular Maintenance" FAQ at the top of this page for further details.

This is a perception that is most commonly noted by owners that have recently switched to a combi-boiler or a tankless water heater after moving away from using a heated storage tank to produce and store Domestic Hot Water (DHW).

Here's why:

Heated Storage Tanks - The water contained in such a water heater is being heated throughout the day and night, regardless of whether you are using it or not.

The benefit of course, is that the stored water is already hot and ready for use at any time.

However, that means that energy is being used just to keep a large supply of hot water on standby. You are paying to heat and store water all the time, just to use it sporadically through the day.

In addition to the ongoing energy use, you will also only be able to use as much hot water as the tank can store, and once the hot water is depleted, you will need to wait until the fresh cold water has been heated up and ready to use.

Combi-Boilers & Tankless Water Heaters - These types of water heating products only produce hot water when the owner opens a hot fixture somewhere in the home.

This means that no hot water is stored in the product, and so when you open a fixture in the home the water heater will ignite and then start heating the cold water that is flowing through its heat exchanger now. That does mean that there is a small delay in the delivery of hot water to the fixture, and if you previously used a heated storage tank you may notice it.

The benefits though, are significant:

• You are only paying for energy while the product is activated and producing hot water on-demand. When you close the hot water fixture, the product is going to shut down and go back into standby mode.
• You are not limited to a fixed amount of hot water that will deplete and then run cold. As long as you have a hot water fixture open and the product has activated, you will have endless hot water from that fixture until you close it.

Plumbing Distance:

Regardless of whether you are using a heated storage tank, a combi-boiler, or a tankless water heater to produce your home's hot water, there is another delay that must be recognized.

There will still be a delay in the delivery of hot water as the plumbing between the product and the fixtures will contain cold water that will need to be pushed ahead of the hot water that's heading towards the open fixture.

Simply put: The longer the run of plumbing, the longer it will take for the hot water to arrive where it's needed.

Potential Solutions

For the majority of users, the small delay in hot water being produced and then reaching their hot fixtures is of no concern. It is a normal dynamic of hot water that is produced by a combi-boiler or a tankless water heater, and the owner is instead focused on enjoying the lower energy costs!

• If you have a fixture that is particularly far away from the water heating product, and it's one that you frequently use and the delay is problematic for you, then you could use an electric mini-tank water heater as booster. These water heaters are typically 120v and should be installed close to the distant hot fixture and in-line between the main water heating product and the distant fixture. For further details regarding our family of Tronic 3000T electric mini-tank water heaters, please visit this page.

• If you would prefer to reduce the wait time for hot water at all hot fixtures in the home, then we recommend consulting a licensed plumber to discuss the options for installing a recirculating hot water plumbing arrangement. Please visit this page to search for a contractor in your area. Typically, one loop of hot water plumbing will leave the water heating product, travel around the home, and then back to the product. Short plumbing lines to each hot water fixture will then branch off the main loop. A pump and a timer will be used to circulate the water around that loop occasionally, which will also activate the combi-boiler or tankless water heater, and leave hot water in the plumbing loop around the home. The next time you open a hot water fixture you will have less of a wait time for cold water to flush through as it is pre-heated from the last time that the recirculation pump ran.
  Important! Before deciding to install a recirculation loop, be certain that your combi-boiler or tankless water heater can safely be installed in such an application. Some models are designed to be supplied with cold water only and may be damaged if supplied with heated water that is returning from a circulation loop. Consult the literature that came supplied with your product. If you no longer have the printed literature that came supplied with your product, an electronic copy can be downloaded from our manuals download page.

All tankless water heaters operate by sensing that water is flowing through it (caused by the user opening a hot water fixture in the property), and then activating the burners to heat the moving cold water.

If the volume of flowing cold water is not enough to exceed the minimum flow rate required to activate the water heater, the appliance will not turn on.

Insufficient water flow could be caused by;

1. The hot water fixture at the point of use (sink faucet, shower etc) may be a low-flow variant, designed to minimize water flow. If this is the case, try removing any aerators or flow restrictors from the fixture to increase the water flow rate.

2. There could be a plumbing crossover failure somewhere in the property (a common failed plumbing component is the shower mixer valve). A plumbing crossover will allow cold water flow to mix in with the hot water flow, and can slow the hot water flow down enough to cause issues with activating the tankless water heater.

3. Clogged inlet water filer. There is a small mesh filter screen inserted inside the water heater's brass cold water connection fitting. Over time, debris from the water supply may cause the filter to clog, and this will slow the water flow down. As part of regular maintenance, it's important to remove and clean the inlet water filter screen.

Please refer to this service bulletin for further assistance; Temperature Fluctuation Bulletin (PDF 0.2 MB)

All tankless water heaters operate by sensing that water is flowing through it (caused by the user opening a hot water fixture in the property), and then activating the burners to heat the moving cold water.

If the volume of flowing cold water is not enough to exceed the minimum flow rate required to keep the water heater activated, the appliance may shut down during hot water use.

Insufficient water flow could be caused by;

1. The hot water fixture at the point of use (sink faucet, shower etc) may be a low-flow variant, designed to minimize water flow. If this is the case, try removing any aerators or flow restrictors from the fixture to increase the water flow rate.

2. There could be a plumbing crossover failure somewhere in the property (a common failed plumbing component is the shower mixer valve). A plumbing crossover will allow cold water flow to mix in with the hot water flow, and can slow the hot water flow down enough to cause issues with activating the tankless water heater.

3. Clogged inlet water filer. There is a small mesh filter screen inserted inside the water heater's brass cold water connection fitting. Over time, debris from the water supply may cause the filter to clog, and this will slow the water flow down. As part of regular maintenance, it's important to remove and clean the inlet water filter screen.

Please refer to this service bulletin for further assistance; Temperature Fluctuation Bulletin (PDF 0.2 MB)

Safety Notice - This is a gas-fired water heater. Only professionals who are qualified to work on such equipment should do so!

If you are in need of a qualified professional in your area, please use this contractor search page;

An "EA" error code on the display (sometimes mistaken by the user for "ER") means that the water heater tried to ignite the burners three times when water flow was sensed, but the burners did not ignite after the attempts.

The most common causes for the appliance failing to achieve combustion are;

1. A liquid propane model being supplied with natural gas (or vice versa).

2. The gas supply pressure to the water heater being insufficient;

a. NG models require an absolute minimum of 5" water column of gas pressure in high fire to operate correctly (the maximum allowable gas supply pressure is 14" water column).

b. LP models require an absolute minimum of 11" water column of gas pressure in high fire to operate correctly (the maximum allowable gas supply pressure is 14" water column).

3. Undersized gas supply piping. This is a 175,000BTU water heater, and the gas supply installation needs to be sized and installed accordingly.

4. The water heater's gas valve may be out of calibration, and so the air/fuel mixture may not be ideal for combustion. Checking the calibration (and adjusting if needed) should be done when installing the water heater above 4000ft elevation, after carrying out a gas conversion from LP to NG (or vice versa), or after installing a new gas valve.

5. Damaged or dirty spark electrodes.

6. Damaged burner tray or gas valve.

7. Rain coming through the exhaust vent pipe and into the burners, fan motor, and gas valve. If this has happened, we recommend replacing the water heater entirely as it is unsafe to try to reuse the appliance after it has been water-damaged.

8. Insufficient combustion air, potentially caused by;

a. If twin-pipe install, the air intake pipe or termination may be damaged or blocked.

b. If using room-air, the volume of the area may be too small to contain enough oxygen for the water heater (especially problematic if there is an extract fan or another combustion appliance in the area too).

Please refer to these service bulletins for further assistance;

EA Code Bulletin (PDF 1.6 MB)

Check Gas Pressure Bulletin (PDF 0.5 MB)

Measuring CO2 Bulletin (PDF 1.1 MB)

Condensation And Rain Requirements Bulletin (PDF 0.4 MB)

Replacing/Cleaning Electrodes Bulletin (PDF 1.2 MB)

Gas Conversion Bulletin (PDF 1.7 MB)

Safety Notice - This is a gas-fired water heater. Only professionals who are qualified to work on such equipment should do so!

If you are in need of a qualified professional in your area, please use this contractor search page

An "EC" error code on the display means that the water heater did achieve combustion on a call for hot water, but combustion was lost even though the demand for hot water was still active.

The most common causes for the appliance losing combustion are;

1. A liquid propane model being supplied with natural gas (or vice versa).

2. The gas supply pressure to the water heater being insufficient;

a. NG models require an absolute minimum of 5" water column of gas pressure in high fire to operate correctly (the maximum allowable gas supply pressure is 14" water column).

b. LP models require an absolute minimum of 11" water column of gas pressure in high fire to operate correctly (the maximum allowable gas supply pressure is 14" water column).

3. Undersized gas supply piping. This is a 175,000BTU water heater, and the gas supply installation needs to be sized and installed accordingly.

4. The water heater's gas valve may be out of calibration, and so the air/fuel mixture may not be ideal for combustion. Checking the calibration (and adjusting if needed) should be done when installing the water heater above 4000ft elevation, after carrying out a gas conversion from LP to NG (or vice versa), or after installing a new gas valve.

5. Damaged or dirty spark electrodes.

6. Damaged burner tray or gas valve.

7. Rain coming through the exhaust vent pipe and into the burners, fan motor, and gas valve. If this has happened, we recommend replacing the water heater entirely as it is unsafe to try to reuse the appliance after it has been water-damaged.

8. Insufficient combustion air, potentially caused by;

a. If twin-pipe install, the air intake pipe or termination may be damaged or blocked.

b. If using room-air, the volume of the area may be too small to contain enough oxygen for the water heater (especially problematic if there is an extract fan or another combustion appliance in the area too).

Please refer to these service bulletins for further assistance;

EC Code Bulletin (PDF 1.0 MB)

Check Gas Pressure Bulletin (PDF 0.5 MB)

Measuring CO2 Bulletin (PDF 0.5 MB)

Condensation And Rain Requirements Bulletin (PDF 0.4 MB)

Replacing/Cleaning Electrodes Bulletin (PDF 1.2 MB)

Gas Conversion Bulletin (PDF 1.7 MB)

An "A2" error code on the display indicates that the flue limiter (or fuse wire on older models) has activated and will prevent the water heater from operating.

The flue gas limiter (or fuse wire, on older models) is in place to prevent the water heater from firing in the event that hot flue gases are entering the top half of inside the metal cabinet.

The flue gases may be present if;

1. The exhaust venting or end termination is blocked, damaged, or incorrectly installed.

2. The gaskets around the top or bottom of the heat exchanger are damaged.

3. The sight glass mounted in the front of the heat exchanger is damaged or it's white gasket is damaged.

If you have verified that none of the above potential causes are evident, then it could be the case that the flue gas limiter (or fuse wire, on older models) is defective or disconnected.

Please refer to this service bulletin for further assistance; A2 Code Bulletin (PDF 1.7 MB)

An "E9" code displayed on the screen means that the temperature limiter that is attached to the top-right corner of the copper heat exchanger has detected an overheat and tripped.

The cause of this in almost all cases is that the inside of the heat exchanger water pipes is clogging up with lime scale.

Factors such as the hardness and quality of your water supply, and the temperature that you have set on the water heater's control, will determine how quickly scale will form in the water heater and how severe it becomes.

The issue will likely begin with occasional appearances of the E9 code, but the frequency is likely to increase if the lime scale is not addressed.

Please refer to these service bulletins for further assistance;

E9 Code Bulletin (PDF 0.5 MB)

Descaling The Heat Exchanger Bulletin (PDF 1.0 MB)

It is critical that the water heater be installed in a manner that does not expose it to freezes!

Frozen water expands, and if that happens inside of an object (such as the heat exchanger piping and water valve of this water heater), rupturing of the object can happen.

Damage to the water heater caused by freezing is not covered under warranty.

The two most common causes of the water inside the water heater becoming frozen are;

1. The water heater was installed in an unconditioned space, where the ambient temperature has dropped below freezing. The only viable solutions to this are;

a. Heat the area in which the water heater is installed.

b. Move the water heater to a conditioned space.

c. Drain the water out of the water heater completely when freezing temperatures occur.

2. Negative air draft. Freezing outside air is being pulled down the water heater's exhaust pipe from the outdoors when the appliance is on standby. This is called a negative air draft and is most commonly caused by another combustion product in the home (boiler, furnace, wood stove etc) using the area's available air for combustion. If the area's air starts to deplete, nature will simply try to remedy that by pulling in more air from wherever it can get it, including from outdoors via a tankless water heater's exhaust piping.

The best way to minimize the risk of that happening is to ensure that you have "twin-piped" the water heater (you are using an intake air pipe connected from the water heater directly to the outdoors instead of trying to use room air) and the front cover is in place tightly.

Please refer to this service bulletin for further assistance;

Twin Pipe For Freezing Climate Bulletin (PDF 0.4 MB)

If the exhaust piping for the water heater has been installed in a manner where rain, or even condensation, can flow down into the water heater, then critical damage to the burner tray, fan motor, and the gas valve may occur.

For details on the best exhaust installation methods to avoid water damage, please refer to this service bulletin;

Condensation And Rain Requirements Bulletin (PDF 0.4 MB)

Both of these codes relate to the temperature sensor that is clipped on to the hot water outlet pipe inside the lower-left corner of the water heater.

The most common causes of the issue are;

1. The sensor is not making good contact with the copper pipe.

2. The two red wires connected to the sensor may be loose or damaged.

3. The sensor may be defective.

4. The sensor may be working perfectly and is sensing water temperature that is higher than the desired set point (in this case, you may also see "E9" codes too).

Please refer to these service bulletins for further assistance;

A7 Code Bulletin (PDF 0.6 MB)

A9 Code Bulletin (PDF 0.6 MB)

Testing And Replacing Temperature Sensors Bulletin (PDF 0.6 MB)

Safety Notice - This is a gas-fired water heater. Only professionals who are qualified to work on such equipment should do so! If you are in need of a qualified professional in your area, please use this contractor search page

As with all water heating equipment, there are maintenance requirements that must be carried out at regular intervals to ensure that the appliance continues to operate safely and at its intended performance.

The following list is a general overview of the required annual maintenance points, and as such may not cover all steps that are required for your specific model;

Annually

1. Check the exhaust venting (and air intake piping, if used) to ensure that there are no blockages or damage in the pipe or the termination.

2. Check that the backdraft flapper inside the exhaust collar is moving freely.

3. Check the sight glass located in the lower-right corner of the copper heat exchanger to ensure that there are no cracks in the glass or damage to its gasket. In addition, look at the burner flames through the sight glass when the water heater is running to ensure that the flames are steady and blue.

4. Manually operate the pressure relief valve (located in the plumbing below the water heater) to ensure that it opens and water comes out.

5. Ensure that the small mesh filter screen that is located inside the brass cold water connector is clean and undamaged.

6. Prevent lime scale build up by carrying out a descaling flush with white vinegar.

7. Remove the exhaust vent hood inside the water heater and inspect the top of the copper heat exchanger for soot or debris clogging up the fins.

For full maintenance steps and procedure instructions, please refer to the installation manual for your specific model. You can download a copy of the manual from the links on this page