Agree. It was stupid to have one T-stat and 2 heaters. I have them separated now with new transformer, new T-stat, new wire run and all seems to be working fine.
I have also read that a short in the wiring to the thermostat can also cause problems with the transformer. I have been using one thermostat to control two different heaters - which is not ideal. This is a good chance for me to split these and get a new "old school" Honeywell round dial...
I am putting a 3-amp inline fuse in the secondary of the new transformer. I don’t want my bad root-cause analysis to toast a third transformer
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Having said all of that - it is still fishy to me how I could have two bad transformers and a bad exhaust fan motor. It sure seems like I'm winning the "bad furnace luck" lottery. It is still possible that I am simply missing something obvious. The transformer will be here in 3 days.
Thanks for your thoughtful reply!!! I have seen the roll-out switch fault last year when my burner screens plugged up. The flame was, indeed, rolling out where it should not be and the switches worked as advertised. This is not the case now as the screens are clear and the blue flame stays...
Per Mr. Heater, the LED should flash slowly when it has 24 volts and no request for heat. It should flash fast when it gets a request for heat. They agree that the LED should never be dark whenever 24 volts is present. Their first diagnosis was "bad board" with the symptom of "dark LED".
It has to be the transformer. Mr. Heater is sending me out another one under warranty. I did replace it just 2 weeks ago - but it was not directly from them. It also fits the symptoms. I verify 110 V on the upside, but don't see 24 volts on the blue/yellow pins when the LED is dark. When the...
So - I got the "official" Mr. Heater Big Maxx control board. It looks identical to the one I had. Even the "QC" ink stamp is in the same spot. I swapped it out and still have the same issue: Runs great for 3 minutes with fast-blink LED, then shuts off with a dark LED. Wait 5 minutes and it...
I went to the Mr. Heater website and chatted with Tech Support. That green LED should never be completely dark. The tech suggests a new circuit board. I did just replace it, but I admit it that I did not order it directly from them (SKU #60105). So - another one is on the way. In the "I'm a...
OK - I now have a new circuit board, new transformer and new fan. The fan was clearly bad - but I'm not sure about the rest. The furnace fires up fine with no flashing codes. It runs hard for ~5 minutes and shuts down. After another 5-10 minutes, it fires right back up. During this down...
All good now. My new fan and motor assembly arrived today. I wired it up on my bench and it ran as expected: you wouldn’t stick your finger in there. It blows hard. I work with an electric
Motor design guru and he explained the most likely issue. Single-phase, 110-volt motors have two...
Hi all!
Has anyone heard of the exhaust fan on a Big Max heater simply running too slow? Mine runs, but does not trip the pressure switch. It is also so quiet, I cannot hear it turning. I pulled it apart and ordered a new motor.
My initial complaint was intermittent heat with no LED...