Heater shuts off and makes noise

[RunGoalieRun]

Hi Everyone,
I'm having issues with my Pentair Max-E-Therm 200 heater. Its about 4 years old and has been running perfect until this weekend. The heater will start up, the blower activates and then I hear the flame fire up. After 10 seconds it shuts off and there is a knocking sounds coming from the manifold. I've removed the plumbing and it looks like the Manifold bypass is in tact. The Thermister was tested in a cup of boiled water and it appears to work as well. My variable speed pump runs at 2000rpm when the heat mode is active. The only way to make the heater work is to run the pump at full speed, which I've never had to do. I cleaned the filter and checked the basket, there does not appear to be any issues with water flow. Before I place the service call, any other troubleshooting tips I can try? There are no error lights except a very brief flash f the PS (Pressure Switch) which I have tried to bypass as well.

Thanks

 

[Poolbreh]

Hi,
The system requires 20gpm. You mentioned if you run at full speed it works fine. It sounds like a flow issue to me.
have you checked and cleaned impeller on the pump?
what is the psi on the filter?
is it a pool spa combo?

 

[Poolbreh]

And are you sure the bypass is intact? Did you take the manifold off to inspect it?

 

[ps0303]

What type of filter do you have? Checking the PSI on the filter gauge is many times useless as those gauges are not the best unless you have one that contains the glycerin in it. 2000 RPM on the filter pump is not adequate for heaters to heat correctly. I also suggest 2900-3100 RPM on pump speeds.

 

[RunGoalieRun]

And are you sure the bypass is intact? Did you take the manifold off to inspect it?

I did not. I ordered a new one that arrived today, I’ll take the manifold apart tonight to inspect, but from everything I’ve read, that’s most likely the issue. I’ll report back tomorrow. Thanks

 

[RunGoalieRun]

What type of filter do you have? Checking the PSI on the filter gauge is many times useless as those gauges are not the best unless you have one that contains the glycerin in it. 2000 RPM on the filter pump is not adequate for heaters to heat correctly. I also suggest 2900-3100 RPM on pump

I did not. I ordered a new one that arrived today, I’ll take the manifold apart tonight to inspect, but from everything I’ve read, that’s most likely the issue. I’ll report back tomorrow. Thanks

2000 rpm is the speed it has been set at for 4 years when the heater turns on. I run the pump at 1600rpm normally, just enough to keep the salt cell from complaining

 

[wireform]

I did not. I ordered a new one that arrived today, I’ll take the manifold apart tonight to inspect, but from everything I’ve read, that’s most likely the issue. I’ll report back tomorrow. Thanks

I hope you also got a new set of orings and the rectangular oring for the manifold to go along with your work otherwise don't open it till you have them. Orings don't always seal second time around.