Pentair MiniMax NT LN 400DV Propane Heater Problem

[BobbyZ]

Hi folks, I've been pulling my hair out trying to run down the problem of why my heater will not ignite the burners. I've cleaned the jets out, checked the gas pressure coming in to the gas valve ( I have 12" WC as indicated on the decal inside the heater compartment that it requires). Cleaned off the flame sensor, checked voltage to the valve and got 27 volts. I can hear the valve click after a bit when the hot surface ignitor glows red, but there is no gas flow out of the valve when this happens ( I hooked up manometer to the output side of the gas valve to check). What am I missing?

 

[ajw22]

You sure the switch by the gas valve is turned on?

@swamprat69 may have ideas.

 

[swamprat69]

I am assuming that with a gas valve inlet pressure of 12"WC that you have a propane heater? How old is the heater? Photos of the heater, heater nameplate (decal), gas piping to the heater, gas valve and heater with both front doors off would be helpful. What did you measure as the outlet pressure at the gas valve?

 

[Poolbreh]

I am also assuming it’s propane based off the wc inlet. Are you getting a difference of 2” on the output side? You should check the tank and make sure it’s full even if the pressure gauge indicates it(bad pressure gauge). You might be getting readings on compressed air in the lines. It sounds like the valve is opening.

 

[BobbyZ]

Pool Heater wont fire up..... After replacing numerous parts on my pool heater, I think I finally found my problem. I tested pressure with manometer at the gas valve with heater in off position. I get a pressure reading of 11.7" WC (Static pressure). When heater calls for heat and gas valve opens I get a pressure reading of .36" WC and manifold pressure reading of .06" WC. My tanks have plenty of Propane in them. I'm thinking the pressure regulator on tanks is bad. The tanks and regulator were installed less than 2 years ago. We are in Lake Havasu City, Az. New gas valve, Control Board, Hot surface igniter, Ignition Module have been installed.