Pentair Mastertemp 300 won't fire, LED 11 only one lit

Dec 4, 2016
6
Folsom/ca
Hi Everyone! Brand new to the forum. A little backstory here. My wife and I just bought our first home! We decided to use a friends pool inspector for the pool inspection prior to writing an offer. He came out and told us everything was fine. So everything moves along and the deal closes. We move everything in, I'm tired and thinking a good soak in the hot tub is just what I need. So it hit the spa button, noises start happening, and I wait for the temp to go up. A few minutes pass and the temp isn't changing. So I walk around to the heater and the service heater light is lit up. Great!!

So I do some research and get all kinds of different answers. Everyone seemed to think the igniter was to blame. Replaced that and same thing happened. So I finally get the nerve to take the panels off and flip over the cover to check the RED service leds. The only one lit is LED 11, which is the same led that lights up the service heater light when viewed from the front. I can't seem to get a straight answer as to what may be causing this. A bit more info, green "spa on" light is on, the blower blows, I can smell gas from the exhaust and I can hear a clicking noise, but nothing happens, then the red service heater light turns on.

Can anyone shed some light pleeeease?

TLDR: Heater doesn't fire. Blower runs, gas can be smelled from exhaust, hear clicking noises, service heater light comes on. Control panel LED 11 is lit up, no other RED LEDs are lit. Green "spa on" LED is lit.

Thank you in advance!
 
Knowing if the ignitor gets hot is a question to answer. You can carefully feel down around it when it tries to light up. Careful as the metal will get very hot. It is possible that the ignitor isn't getting powered which would then signal that the control module might be bad. You can also check with a volt meter to see if the ignitor is getting powered. When you removed the old ignitor, did it look to be wet or have what might look to be a water line on it?
 
Knowing if the ignitor gets hot is a question to answer. You can carefully feel down around it when it tries to light up. Careful as the metal will get very hot. It is possible that the ignitor isn't getting powered which would then signal that the control module might be bad. You can also check with a volt meter to see if the ignitor is getting powered. When you removed the old ignitor, did it look to be wet or have what might look to be a water line on it?

Thanks for the reply! I haven't touched around where the igniter is. I'll try that. Here's what the old one looks like on both sides. Is that normal?

Edit: The area around the igniter is warming up each time I try to fire the heater.

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Use an ohm meter to check the resistance of the igniter.

You can also check that the igniter is getting 120 volts.

You can put 120 volts on the igniter to see if it gets hot. It will get to about 1800 f. So, don't let the metal touch anything.
 
OK so it seems to be getting some power since it's warm to the touch. If you can get a volt meter and see if it's getting 120V. Just disconnect the ignitor and then put your probes in and get a reading when the unit is turned on and trying to light. I don't see anything on the old ignitor to indicate that there might be an issue with it.
 
Do the flange bolt test... If you smell gas and get the clicks, and you have changed the igniter, i would guess either tub is full of water or FENWAL isn't closing. Although warm igniter may rule out FENWAL. Maybe pull igniter and confirm that it glows? Flange bolt is easier check and should be done first.

Where is my copyrighted picture Paul? Post it for bolt location.
Or was that picture for the therm by-pass???
 
Thanks for the replies everyone! I was going to pull the igniter and see if it started glowing, but I didn't want to risk an explosion with the gas coming from the exhaust. I'll try pulling one of those bolts. Fingers crossed no water comes out......
 
You can take the igniter out and check ohms.

You can then put an alternate 120 volt supply on the ignitor away from the heater to see if it gets hot.

You can check to see if the controller is putting out 120 volts where the ignitor plugs in.
 

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Thanks again for all the responses. I wanted to post the resolution even though I feel slightly dumb for not noticing this on first inspection. It turns out that a rat or mouse got in to the heater. It chewed a hole in the plastic air inlet to make room for itself (see pic). I had the whole heater apart yesterday thinking there was a nest in the combustion chamber. Turns out there was nothing in there. Although the perforations in the flame holder assembly were partially clogged with rat fur. Seeing that made me think maybe the gas isn't reaching the igniter due to the fur, better clean it out....insert light bulb moment right here :idea: maybe since the air intake hole is too big now because of the rat, too much air is getting in creating too lean of a mixture? I cleaned the perforations anyway, and then fixed the hole in the intake. Turns out there also was a gasket missing between the flame holder assembly and blower adapter plate. The insult to injury part was when I removed the blower assembly I bumped the igniter on something and promptly shattered it. So I popped in the old one....Put everything back together and it fired up. SMH, it's usually the simplest fix. All's well that ends well however! Now I need to make/buy a spa cover....one project finished and another pops up!
Thanks again everyone!
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Visual inspections is a huge part of diagnosing issues. Definitely replace the air orifice.

Mice, rats, snakes, and more creatures love the Pentair products. Easy access to get in and live. So when you have issues with these units the first thing to do is a visual inspection and look for anything that has been chewed on. What you see with the air orifice is very common along with chewed wires. So visually inspect the units for any of this before tearing it apart.
 
Here's a picture of the "fix" I did. The hole match up perfectly with a large socket I had. I cut a template then taped it in and filled the gap with impression material that a dentist would use on your teeth! LOL. Worked though. Here's the new one next to the old, and then the steps taken to ensure Stuart Little doesn't wreck my hot tub plans again!!
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