CWH
companion water heater
Troubleshooting
1 Undersized expansion tank?
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Insufficient allowance for expansion on the boiler side can cause the boiler pressure relief valve to lift.
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The tank must be sized to handle the total volume of water in the boiler system, the boiler and all inter-
connecting piping. The volume for the CWH boiler piping and heat exchanger is 1.4 gallons.
2 Faulty boiler expansion tank?
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Is the expansion tank defective, waterlogged or improperly charged?
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Check for failed gaskets or bladders, or a faulty Schraeder valve.
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Tank must be isolated and pressure relieved from boiler side when testing.
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Use a tire gauge to check the charge pressure of the tank.
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Turn the boiler limit up to a higher setting and let the system run at a higher temperature. This will
simulate maximum expansion in the boiler system.
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If the boiler relief valve lifts and/or there is a significant increase in the boiler system pressure, the
expansion tank is flooded or undersized.
3 Faulty boiler relief valve?
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Is the boiler pressure relief valve functioning properly? Dirt and water deposits can accumulate under
the valve seat.
4 Faulty boiler fill valve?
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Is the valve filling to the correct pressure?
5 Tank heat exchanger coil leaking?
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Turn the boiler power OFF.
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Close the boiler supply and return isolation valves.
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Isolate the water heater from the domestic water system by closing isolation valves.
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Attach a hose to the water heater drain valve (if not directly connected to a drainage location).
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Open the water heater drain valve to allow the tank-side pressure to drop.
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Watch the pressure on the boiler P/T gauge. If this pressure drops noticeably, there is a leak in the piping
or in the tank heat exchanger. Locate the problem and correct. Replace the CWH tank if necessary.
34
— Product Manual
(continued)
Boiler relief valve lifting or weeping
Part number 635-500-156/0113