Mastertemp 400 heater, no ignition

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ering210

Member
Jul 29, 2021
13
San Diego, CA
Hi,

I have a pentair mastertemp 400 that isnt heating. Last week, I was outside when my wife turned it on and I heard a bug pop and the circuit breaker popped. The noise sounded like more than the breaker.

The symptom is that the blower runs, I smell gas, and the heater never fires.

There were no codes so I opened it up and started troubleshooting. I looked at the bottom of the circuit board and only the Service Heater light was on, none of the diagnostic lights were lit.

I have had rats chew through wires in the past so started looking around. I the discovered that the leads for the igniter were completely stripped bare (pics below)! My strong suspicion is that those bare wires finally arced and shorted, causing the circuit to trip. I then ordered and installed a new igniter. After installation, I verified that the resistance of the igniter is in range (57 Ohms) and tried firing it up again. No luck. Same problem.

I then opened the metal box for the ignition control. After going through the attempt to start the ignition, the light on the control module blinks 3 times, indicating ignition lockout. I also tried to take a voltage reading on the leads going to the ignitor but never got a reading. The troubleshooting manual has some notes about reading this with a digital meter but says the reading should not be 0 or 240v. I got 0.

Before I order a new ignition control, is there anything else I should be trying?

Thanks in advance,
Eric
 
Seems like you get a lot of weird electrical problems?

What was the resolution on those issues?

Maybe a stray electrical current or something is not wired correctly?

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ering210 said:
Hi,

I have a pentair mastertemp 400 that isnt heating. Last week, I was outside when my wife turned it on and I heard a bug pop and the circuit breaker popped. The noise sounded like more than the breaker.

The symptom is that the blower runs, I smell gas, and the heater never fires.

There were no codes so I opened it up and started troubleshooting. I looked at the bottom of the circuit board and only the Service Heater light was on, none of the diagnostic lights were lit.

I have had rats chew through wires in the past so started looking around. I the discovered that the leads for the igniter were completely stripped bare (pics below)! My strong suspicion is that those bare wires finally arced and shorted, causing the circuit to trip. I then ordered and installed a new igniter. After installation, I verified that the resistance of the igniter is in range (57 Ohms) and tried firing it up again. No luck. Same problem.

I then opened the metal box for the ignition control. After going through the attempt to start the ignition, the light on the control module blinks 3 times, indicating ignition lockout. I also tried to take a voltage reading on the leads going to the ignitor but never got a reading. The troubleshooting manual has some notes about reading this with a digital meter but says the reading should not be 0 or 240v. I got 0.

Before I order a new ignition control, is there anything else I should be trying?

Thanks in advance,
Eric
Click to expand...

You mentioned pictures but I don't see them?

I think you're well ahead of most in terms of diagnostic. A new fenwall is relatively cheap compared to most heater parts and is a logical next step.

#476223

Beyond that, as James suggested, it could be other damaged wires. The "pop" you heard should have left a black mark somewhere.
 
ering210 said:
Before I order a new ignition control, is there anything else I should be trying?
Click to expand...
How old is your MasterTemp? I have a Fenwall here from mine (2019) that I replaced with the new version to allow RS 485 communication. I would be happy to donate to you to get it off my workbench, if you will pay for the shipping. I'll use USPS flat rate.

--Jeff
 
Here is the pic.

@Turbo1Ton my heater is about 10 years old. That would be fantastic! I'd be happy to pay shipping. Venmo? Paypal? Let me know!

@JamesW I assume you're looking at the Jandy boards I had to replace a couple of years ago. My best guess is that that was all related to the Rapsberry Pi I interfaced to get wireless controls. I finally pulled that out and seem to be OK.

ALL of my heater problems have been Rats. They also ate a couple of my Bonsai trees this week!
 

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ering210 said:
Here is the pic.

@Turbo1Ton my heater is about 10 years old. That would be fantastic! I'd be happy to pay shipping. Venmo? Paypal? Let me know!

@JamesW I assume you're looking at the Jandy boards I had to replace a couple of years ago. My best guess is that that was all related to the Rapsberry Pi I interfaced to get wireless controls. I finally pulled that out and seem to be OK.

ALL of my heater problems have been Rats. They also ate a couple of my Bonsai trees this week!
Click to expand...
Yikes.

I'll bet that pop was those leads making contact where they're black and then "boop" goes your ICM.
 
ering210 said:
Yeah...I was pretty shocked to see that. I added 1/4 grid wires to the inside of the panels to keep them out but today I noticed that they actually chewed away the plastic around the exhaust to make the opening bigger! Tenacious little buggers!
Click to expand...
Yes indeed. We've used the MKRatproofing kits with success, plus a couple green poison bricks inside just in case 😉
 

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Yes, the MKRatproofing screens install on the outside of the heater.
 
ering210 said:
I want to thank you guys, especially Turbo1Ton who sent me a replacement Fenwal for the price of shipping! I am back up and running!

I also just received my MK Ratproofing kit which I will install tomorrow. Do you typically install these on the outside of the unit?

Thanks again!
Click to expand...
Glad it went to someone who could use it. I offered it up for sale a while back and had no hits on here, or on Ebay. Happy to RAK and just ask that you do the same in the future!

--Jeff
 
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