Master temp 300 starts then stops.

[chrger1970]

My 10 year old Master temp 300 will go thru its start up, I smell gas, it will start and the exhaust is warm then it stops and try’s to start two more times. I pulled the tap off and found what looks to be the U11 LED light on. I already changed the AGS, high limit and flue sensors. I bypassed both sensors on the other side of the heater as well. The igniter has around 50 ohms so it should be good. Any ideas?

 

[ajw22]

AGS errors are usually caused by a bad internal bypass. Too much water is bypassing the heat exchanger internally. What water that is going through is coming out too hot and tripping the AGS switch in the manifold.

Could also be the thermal regulator.

When did you last clean your filter?

Your problem is more likely a water flow problem then a sensor problem.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

 

[chrger1970]

AGS errors are usually caused by a bad internal bypass. Too much water is bypassing the heat exchanger internally. What water that is going through is coming out too hot and tripping the AGS switch in the manifold.

Could also be the thermal regulator.

When did you last clean your filter?

Your problem is more likely a water flow problem then a sensor problem.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

I checked the thermal regulator and found it was gone. So I ordered it an installed it today. I’m thinking the spring rusted away and the thermostat is somewhere in the plumbing. After installing it and trying to see if it worked, it have me a E01 code and would not go thru the cycle. I pulled off the control board to see how it looked and saw some rust. After putting it back, I could get anything. I’d I hit the reset button I was just getting the # 90. Looks like I might need a board huh?

 

[ajw22]

I’m thinking the spring rusted away and the thermostat is somewhere in the plumbing.

You need to remove the header and find the pieces. They are probably blocking the water flow and causing your AGS errors.

After installing it and trying to see if it worked, it have me a E01 code and would not go thru the cycle.

E01 is a bad water temperature sensor.

Connect a 10K resistor to the temperature sensor wires. If the heater runs and shows a water temp of 76F then replace the sensor. If it still does not run then replace the board.

I pulled off the control board to see how it looked and saw some rust. After putting it back, I could get anything. I’d I hit the reset button I was just getting the # 90. Looks like I might need a board huh?

I don't knwo where the # 90 is showing up,