I have model PH-12M-DN the pilot light will come on and stay light but when I turn the water on to demad the unit kick on it does not...I am guessing maybe a bad pressure switch but have no manual for this and can't find one on line. The unit is about 10 years old but is used in my poohouse and is on only half the year at most..It has worked perfectly every time I have turned it on in the past..any suggestions ?
Tankless Water heaters have a automatic pilot and digital water temperature control system; you have to turn on the water in the house to get it to kick on that is unless you have a circulation pump on a timer. If the gas supply doesn't have atleast a 2" rating that with cause the tankless to malfunction because it's not getting enough gas pressure; certified professionals rarely make this mistake. Moreover, if you don't have a water softener you are using with the tankless you voided your warranty; the minirals clog the heat exchanger.
The Paloma PH-12M-DN is an older legacy series model. It has no digital water control system. It uses a water manifold and water pressure differential to open the gas valve via a rubber/metal diaphragm. If the unit has gas and the pilot is on and still no flame appears when the hot water tap is fully opened you probably have a hole in the rubber diaphragm which opens the gas valve. I have had this unit in my home for 30 years and have found the unit to be very reliable but somewhat affected by back pressure issues shutting of the gas when cold water is added to moderate the temperature. Other issues which would prevent the gas valve from opening are a bad thermocouple or gas valve but I have never had these fail. I replaced the diaphragm once in 30 years. I think it was in 1992.
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I have a Paloma Tankless Water Heater, Model #PTG-74PVN-2. It usually works great. Once in a while it just stops producing hot water for about 5 minutes and then goes right back in. It could be in the middle of a shower, and it just stops. I have no error message, but have not checked the board during a problem because I'm usually in the shower.
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The pilot light and main burner won't stay on in my Paloma water heater.
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