To avoid these ads, REGISTER NOW!

I have a Mr Heater mhu50 with a 2 code flash issue,

Rich090

New member
Joined
Mar 28, 2025
Messages
1
Hello,

I bought this heater about 5 months ago and for two months it ran perfectly, works on the first cycle every time, then 2 months after all the issues started happening.

Let me start from the beginning

Issue 1: heater would not turn on, power was fine, tested it. turns out there was a burnt fuse, replaced it, but still wouldn't turn on. Spoke with furnace tech and he mentioned a few things, but he also mentioned to check the propane coming in, he asked if the tanks were empty, I said no, but turns out after going through the list of things to check that he gave me, turns out the tanks were empty, gauges were stuck (Gets cold here), had propane refilled and gauges fixed but still furnace didnt work. Tech came in and turns out it was the transformer, he replaced it and it started up

Issue 2: All seemed fine for a few start ups after the tech left, maybe even for a day or two but only on the 2nd or 3rd cycle, then more issues, no codes, just wouldnt keep flame after trying to ignite. After cleaning igniter and flame sensor, cleaning and blowing the area for any dust, the heater would start, but only sometimes. I cleared the tube to the pressure switch, blew in the plastic tube to clear any debris. Seems to run every now and then, but I have to keep going back to it. Every now and then I also get the 2 code flash. I decided to replace the flame sensor, seemed to not change any results

Issue 3: Now the heater won't ignite at all, I noticed I wasn't getting any heat, so I went to the heater and unplugged it, waited a bit and started it back up. Draft inducer started, then when it tries to ignite I hear the click sound but it sounds like its coming from the pressure switch, doesn't sound electrical like the igniter. Sounds more like the click sound the switch makes, and its about 3 clicks.
I do get a 2 flash code, which is odd I think, should be 3 flashes if its the pressure switch but seems with every code there could be multiple problems that could cause the issue.

I did manage to get it to the 2nd cycle at least once, the 1st cycle normal start up tries to ignite but no flame, 2nd cycle tries to start but no ignite just the pressure switch sound i heard before. What I think happened is I disconnected the hose and blew through it, reconnected it to the pressure switch, sucked on the tube to release the lock and then disconnect the tube again and reconnected it to the inducer and blew through the tube to clear any debris and that's it, that got me to the second start up cycle.

Note: I do see a brief light, I believe its the igniter, so this tells me maybe its not the switch and its the igniter itself or maybe gas flow, no idea at this point

Anyways this heater has been driving me nuts, it was working so well in the first 2 months but after the gas being empty, the fuse replacement and then the transformer, im up $600 in costs for tech and parts and still doesn't work properly and every time I read about similar issues, tech say replace the board or replace this or that, might as well buy a new heater at this point.

Well it would be nice to find the issue so it starts like it use to, in the first cycle
 
To avoid these ads, REGISTER NOW!

PoorUB

Well-known member
Joined
Mar 29, 2021
Messages
11,848
Location
Fargo, ND
Two flashes is the heater did not sense flame,

1. Out of gas, or
2. Gas valve didn't open, or
3. Just failed to ignite for some weird reason.

Those are the big three.

I would be certain that you have gas, at the proper pressure, LPG is 11" of water column right before the gas valve. You need a manometer to test it, and you can find instructions on how to make a water tube manometer inline, Google is your friend.

After testing gas pressure, then you need a voltmeter to measure voltage at the gas valve when it is supposed to open. It should open right after the hot surface ignitor lights, and close right after if the burner does not light.
 
To avoid these ads, REGISTER NOW!
Top Bottom