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

[JamesW]

Since you are getting ignition, it is probably not an ignitor problem.

Most likely, it is low inlet gas pressure causing low manifold pressure, which causes low Flame Current.

Check Inlet gas pressure and address as needed.

If inlet is good and manifold is still low, increase gas pressure to make it read -0.2" w.c.

Once you get -0.2" w.c on manifold and there is still a problem, check Flame Current.

 

[JamesW]

With the Blower On, both ports are negative pressure (Vacuum or below atmospheric).

With the gas valve closed, the gas port has a more negative pressure than the vent port, which results in a positive reading even though both ports are vacuum.

This is because the gas port is closer to the blower impeller/fan.

This reading is not gas pressure.

With the gas valve open, the vent port has a more negative pressure than the gas port, which results in a negative reading even though both ports are vacuum.

This is caused by the gas pressure pushing the gas port pressure higher than the vent port pressure.

This is also not the actual gas pressure. It is a pressure differential between the gas port and the vent port.
_______________________________________

Blower On and Gas Valve Closed.



____________________________________________________________________________________________

Blower On and Gas Valve Open.

 

[mpmillermg]

Sure, if you get 10 inches when the heater is operating.

Well I don’t think it was the tank, they filled it and changed it from a 1 stage to a 2 stage see video. Also in the video are the gas reading on the inlet side of the gas valve.

Besides replacing the gas valve I don’t know what else it could be.

 

[mpmillermg]

Show where the test leads are connected.

Sorry just getting back on here. They were set up correctly like on the diagram on the manifold side of the gas valve, not the inlet side.

 

[mpmillermg]

Since you are getting ignition, it is probably not an ignitor problem.

Most likely, it is low inlet gas pressure causing low manifold pressure, which causes low Flame Current.

Check Inlet gas pressure and address as needed.

If inlet is good and manifold is still low, increase gas pressure to make it read -0.2" w.c.

Once you get -0.2" w.c on manifold and there is still a problem, check Flame Current.

I will hook up the differential digital manometer again and show you all the connections. I never adjusted the gas valve to get the -0.2 in wc.

 

[JamesW]

Adjust the manifold pressure to -0.2" w.c .

Show the Fenwal Ignition Control Module.

Show the Heater barcode label.

 

[JamesW]

Remove the brass screw cover and then rotate the inside screw clockwise to increase pressure to -0.2" w.c.

The pressure will be going down on the manometer, which is actually increasing the pressure based on how it is connected.

 

[JamesW]

https://www.pentair.com/content/dam/extranet/nam/pentair-pool/residential/heaters/mastertemp/manual/mastertemp-heater-manual-english.pdf