Mastertemp 125 ignition lockout

AFischer1983

Member
May 13, 2020
5
Lawrenceburg Indiana
I opened my pool 2 weeks ago. I fired up the heater. Every worked like normal. The heater is only 2 years old so I didnt expect any issues. I set the heater to 84F. It reached set point and everything was great until last Friday. I came home and notice heater had automatically dropped the setpoint to 65F. I raised it to 84F. Heater kicked on. Came back 20 minutes later. Same issue. I adjusted it back to 65F. I watched it run. It met setpoint of 84F and kicked off. Doing so it lowered the temp to 65F. So this is when I started trouble shooting. I never had any error codes. Go out early the next day to try firing it up. I turn it on. Runs and fires for about 29 seconds and then wint reignite. No led codes and no flashing lights on ignition control module. I find the membrane pad appears shorted as the "off" button wasnt working. Replace it with a new one. Heater fires up for 5 seconds and then wont ignite. I mess with it for 30 minutes and get ni where. I come back about 5 hours later and it fires again in a cold start for about the same 5 seconds then wont re-ignite. I tried dozens of times all day and it will never light. I get zero error codes. I suspect a bad board. So I bought a new one. I still have the same issue. I check the igniter. Pull it out and it breaks very easily. Inspect it and it looks like it possibly had a small hairline crack. I buy a new igniter. Install it. Unit fired up and runs maybe 20 seconds then the same issue. But now I get the 3 flashing lights on ignition control module showing a lockout. Now even after unplugging the unit no matter what it wont fire. I have 54ohms of resistance on brand new ignitor. It glows cherry red. I checked voltage it gets 120V. Flame current is reading 70uA and then will drop to 5uA during the cycling. I read that anything above .7uA is good for flame detection. Could it be gas pressure? Maybe a bad ignition control module? The blower always comes on gas valve clicks and I can smell gas coming out the exhaust. It just will not ignite now.
 

AFischer1983

Member
May 13, 2020
5
Lawrenceburg Indiana
Gas has always been on. I know about the on/off switch on the valve. I always smell gas during startup coming out of the exhaust. I was concerned I'm getting such a high reading on the flame current from the ignition module
 

AFischer1983

Member
May 13, 2020
5
Lawrenceburg Indiana
I'm getting a current reading all the time. 70uA and then 5uA when it cycles. So it appears the ignition control module thinks there is a flame all the time? I read that this will not allow the ignition control module to operate properly?
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
18,072
Northern NJ
I'm getting a current reading all the time. 70uA and then 5uA when it cycles. So it appears the ignition control module thinks there is a flame all the time? I read that this will not allow the ignition control module to operate properly?
That should generate 2 flashes on the FENAL box indicating "flame no call for heat", then the Fenwal is detecting a flame current when it shouldn't be

 

AFischer1983

Member
May 13, 2020
5
Lawrenceburg Indiana
I got my manometer today and checked gas pressure. On inlet side of valve I have 8 in wc. On Outlet side I have 4.22 in wc. When the valve clicks and cycles it drops to 2.9 in wc. I need a little help as I know the heater requires 4 in wc minimum. Is gas valve bad or regulator? Regulator to the heater is factory set at 11 in wc and adjustable to 13.5 in wc. It appears the regulator is already at max adjustment. I guess check after regulator for the pressure and go from there?
 

AFischer1983

Member
May 13, 2020
5
Lawrenceburg Indiana
So I think I figured out the problem and this is just my dumb luck. My 1000 gallon tank in the ground is basically empty. I went to shut the tank off and as soon as I touched the shutoff valve the gauge needle dropped from 35 percent full to 0. I had always thought it was around 35 percent. So it appears while I had pressure I dont have enough volume in the tank and probably why the reading drops over 2 in wc when the valve cycles.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
18,072
Northern NJ
Glad you got it figured out. Note it may take a bunch of start cycles to get the air purged from the gas line after you fill the propane tank.
 

Pool Clown

In The Industry
Sep 5, 2008
2,126
Silicon Valley, CA
For future reference, your W/C readings are on the inlet side of the gas valve. You shouldn't need to adjust the outlet side as that is factory set. Altitude adjustments are made with orifice kits.