Sta-Rite Maxi Therm Pool Heater

[pvosbury]

I have a Sta-Rite propane powered pool heater that has been sitting idle for a few years, with no propane supplied to it. For the last few days I have been trying to get it running, and I have corrected quite a few things that it needed. I replaced the control board and the SFS sensor, and corrected some wire contact corrosion.
The heater now comes on with the green pool light illuminated, and when I select heat the blower starts running and the yellow heating light starts flashing. After trying to start, the service heater light comes on and the blower turns off. On the back of the control board none of the fault LEDs are on.
I am getting 24 VAC to the gas valve (after the expected multi second delay), and I hear it click when the heater is trying to start. I have good gas flow coming out of the low pressure regulator that feeds the heater.

So I am either not getting gas all the way to the combustor, or the igniter is not firing, but I am not sure which it is.
One of my questions is, if the igniter is not firing and that is the only problem, would the gas be allowed to flow all the way to the combustor and therefore I should smell propane coming out the stack. During my attempts to start the heater, there is no smell of propane coming out the exhaust.
Also, if the igniter is firing, does it make enough noise that it can be heard?

I would appreciate any suggestions that can be offered.
Thanks, Pete V

 

[Alexr54]

I had a similar problem. I had to change the igniter because it cracked. Cheap and easy fix for me.
Take the igniter out and check it for cracks.

 

[mguzzy]

you can start off by checking the resistance of the igniter with a Ohmmeter without having to removed it from the heater.

 

[pvosbury]

Thanks to those that are trying to help.
I just checked the resistance of the igniter and it was 60 ohms, and I also checked the voltage going to it when it was trying to fire and it was 120 volts. All of that seems correct.
I took the bleed plug out of the inlet of the gas valve and turned on the gas, and there was good flow.
I also took the bleed plug out of the outlet of the gas valve while the heater was trying to light, held my finger over the hole, and there was no detectable flow. Interestingly enough, when I had the outlet plug removed the heater actually lit off, but only for a brief moment.

Does any of this provide any clues to those of you that have experience with this heater?
Thanks

 

[JamesW]

You can check the gas pressure.

You can also monitor the amperage being used by the heater.

You should see some small amperage before the heater starts and then more when the blower comes on and then another increase when the igniter should be getting hot.

What is the supply voltage to the heater?

 

[pvosbury]

Is it possible to service or repair the gas control valve, because my guess is that it is limiting the amount of propane going to the burner?

 

[mguzzy]

yes.. if you're handy. I took mine apart and cleaned it like I was working on a carburetor. I found the solenoid on the regulator valve had failed and that was preventing mine from working.

 

[JamesW]

I would check that the input pressure is holding steady before I started taking the gas valve apart.

 

[pvosbury]

I have a new high pressure regulator on my in ground tank, showing 10 to 11 psi. There is a new gas line from the high pressure regulator to the heater, but the low pressure regulator at the heater is probably the original, making it many years old.

As I shared earlier I am getting 24 VAC to the gas valve and 120 VAC to the igniter, the blower is running, and the yellow "heating" light is flashing. But the heater does not fire up, unless I remove the pressure tap plug on the outlet side of the gas valve. When I remove this plug the heater fires up for a few seconds, makes a high pitched screeching noise, and then the flame goes out.

Does anyone have any idea why removing the pressure tap plug would allow the heater to fire for a few seconds, make a high pitched noise, and then for the flame to go out? This tells me the gas valve is opening when it gets the 24 VAC signal, and the igniter is firing, but apparently it is not getting enough propane to continue running.

Could a faulty 2nd stage regulator cause this problem?
Thanks to everyone that is trying to help me out.
Pete V

 

[JamesW]

You just need to check the gas pressure with a manometer or have someone do it if you're not sure about what to do.

 

[pvosbury]

Thanks, I will get the gas pressure checked.

Do you have any idea why it momentarily lights up when I have the pressure tap plug removed, but will not light at all when the plug is installed?