Pentair Mastertemp 300 won't fire

[tl605]

Hi all, I'm new here and have been having problems with my heater. I've had a couple people out who just started replacing parts...but it still doesn't work. When I turn the heater on, blower starts...about 30 seconds later it tries to ignite, but doesn't. I get no error codes on the front display and no errors behind the board. So far the following have been replaced:

Thermister
Igniter
Thermal Regulator
Pressure Switch
Board
ICM

I've done the lower manifold bolt test: no water came out...the very tip is rusted.

If there is any other thing you can think of would love the help. But fear it might be new heater time...even though it's only 3 years old

thanks in advance.

 

[JamesW]

Check to make sure that the gas valve in the heater is in the On position.

Check all valves on the gas supply line.

Check the inlet gas pressure before the heater tries to fire and watch the pressure as the heater tries to fire.

Check the voltage and current going to the igniter.

The symptoms point to either no gas or no hot igniter.

 

[tl605]

HI, thanks for the response. One thing I forgot to mention....after it tries to ignite, it starts to smell strongly of gas coming out of the blower. So it's getting gas to the unit. I'll check the voltage going to the igniter...sorry but do you know what voltage that should be?

Also, you don't think the rust on the end of the manifold bolt says anything? When I called pentair they thought it might be and water is inside...but like I mentioned water doesn't come out when you remove the bolt.

thanks!

 

[JamesW]

Voltage should be 120 volts. If the heater is supplied by 120 volts power supply, the voltage will be a clean sine wave and easy to verify.

If the power supply going to the heater is 240, it will use a controller to modify the voltage in a way that a cheap multimeter can't read.

If your supply voltage is 240, you have to use a "True RMS" multimeter to get a valid reading.

You also need to check the current going to the igniter to verify how much power the igniter is using.

The amperage should be about 5 amps, which means that the igniter is using about 600 watts (5 amps x 120 volts = 600 watts).

Just because you smell gas, it doesn't mean that you have enough gas to do anything.

You have to verify the gas pressure before the heater tries to fire and watch it as the heater tries to fire.

You have to use a manometer connected to the inlet pressure tap.

 

[tl605]

HI

Ok thanks. I'll check the voltage to the igniter.

As far as the gas...it had been working fine for the past 3 years, I'm not sure how the actual gas pressure from the line would just change? Is it poss something in the unit is now making it so gas isn't getting to the igniter?

thanks

 

[JamesW]

There's a gas valve in the heater. Is it in the on position?

There will be one gas valve near the heater. Is that open?

There might be a gas valve near the meter. Is that open?

 

[tl605]

Hi

I will check the valve inside the heater.

Yes....the valve by the heater is open

Valve near meter has not been touched at all

 

[JamesW]

You can check the resistance of the igniter to see if it's in range.

The current and voltage will tell us if the igniter is getting hot enough to ignite the gas.

If the igniter is getting hot enough to ignite the gas, then the problem is likely to be a gas pressure problem.

If you can verify that the inlet pressure starts good and remains good, you would then have to check the gas pressure on the manifold side.