Pentair Mastertemp 250 will not stay lit. It lights, but Shuts off after five seconds. Ignition Error message

[mpmillermg]

I have a Pentair MasterTemp 250 LP and I am having a Ignition Error when trying to turn the heater on the pool. I have had the heater going on four years, it worked fine last year and once
I opened the Pool this year it worked one or two days and now it will not stay on. I have troubleshot just about everything I have read that can give you and ignition error. When I turn the heater on the blower comes on, and then you hear a click and the rumbling sound of the igniter igniting the gas. Heat comes out of the exhaust for about 5 seconds and then shuts off, the heater cycles this like three times and then quits and shows the error code.

1. I checked my propane level in the tank and it is at 40%.
2. I replaced the air flow switch.
3. I replaced the ignition control switch.
4. I bypassed the AGS and high limit switch with a jumper and still got the error.
5. I checked the igniter with my ohm meter and it read at 96ohms so it is still good.
6. I tested the gas pressure coming into the inlet side of the gas control valve with an analog manometer. It started off at about 10in./wc before I turned the heater on, when the heater lights it drops to about 4 in./wc and when the heater shuts off the pressure goes up to about 15 in./wc. Then the heater will try to light again and it will drop to about 4 in./wc . I read its not suppose to drop more than 2 or 3 in./wc when it lights but it still should stay on right, just burn rich.
6. I tested the gas pressure on the manifold side(see video) below it does not drop to a negative reading when it fires up.

Any help with this would be greatly appreciated.

 

[setsailsoon]

MP,

Welcome to TFP. Sorry you have to find us with this problem. We've seen this a LOT and it can be frustrating. Seems to happen with all brands at some point and it can be very frustrating to nail down. Random replacement of parts is expensive and mostly just wastes money with no benefit. You seem comfortable with basic diagnostics are you comfortable opening it up to find the Fenwal ignition control module? Find it and let us know how many times it blinks. There are a couple things this can point us to.

Thanks.

Chris

 

[ajw22]

Welcome to TFP.

I suspect you have a propane gas pressure problem. 4” WC is the minimum gas pressure and if it drops to that when running and flames out then you have a gas service problem.

You say your propane tank is 40% but some folks have discovered their gas gauge was broken.

Fill your propane tank and see if you get increased gas pressure.

 

[mpmillermg]

MP,

Welcome to TFP. Sorry you have to find us with this problem. We've seen this a LOT and it can be frustrating. Seems to happen with all brands at some point and it can be very frustrating to nail down. Random replacement of parts is expensive and mostly just wastes money with no benefit. You seem comfortable with basic diagnostics are you comfortable opening it up to find the Fenwal ignition control module? Find it and let us know how many times it blinks. There are a couple things this can point us to.

Thanks.

Chris

Thanks for the quick reply Chris, I know that light you were talking about on the Fenway ignition control module. I have a different model of control module that does not have that light. I attached a picture of the model I have. You can see where there is the red blinking light is supposed to be is a chord that goes up to the panel. Mine will give you the error on the display and the only error I get is an ignition error.

 

[mpmillermg]

Welcome to TFP.

I suspect you have a propane gas pressure problem. 4” WC is the minimum gas pressure and if it drops to that when running and flames out then you have a gas service problem.

You say your propane tank is 40% but some folks have discovered their gas gauge was broken.

Fill your propane tank and see if you get increased gas pressure.

Ok Ajw, I was thinking the same thing since it worked when the tank was at 60% at the beginning of the season? Can I increase the pressure myself on the gas gage, I seen where you do, I just don’t want to break anything or blow myself up of course.

 

[ajw22]

Ok Ajw, I was thinking the same thing since it worked when the tank was at 60% at the beginning of the season? Can I increase the pressure myself on the gas gage, I seen where you do, I just don’t want to break anything or blow myself up of course.

Just fill the tank.

A liquid propane tank takes thermodynamics to change it to gas and develop gas pressure. You cannot simply turn the pressure up.

The tank needs to be full enough to absorb heat fast enough from the air or ground (if it's buried) to boil the liquid propane in the tank to a gas. In the warmer months this is rarely ever an issue unless a tank is grossly undersized.

You have issues with your LP tank sizing or installation not creating enough gas pressure at lower tank levels to feed your heater.

 

[ajw22]

Thanks for the quick reply Chris, I know that light you were talking about on the Fenway ignition control module. I have a different model of control module that does not have that light. I attached a picture of the model I have. You can see where there is the red blinking light is supposed to be is a chord that goes up to the panel. Mine will give you the error on the display and the only error I get is an ignition error.

You have a later model “Connected” Master Temp heater with the 6 button control panel and diagnostics on the display instead of LEDs.

When was that heater installed?