Mr. heater 45000 btu problems

[horspla2003]

I have a 45000 btu Mr. Heater on ng. It has worked good for a while. Went to use it this year, shuts down and get a 4 flash code, no blower operation either. Couldn't find anything wrong, got frustrated in just bought a new one. Swapped it out, new one ran for 10 minutes then quit well before it was up to temperature. It blew the 3 amp fuse in the circuit board. replace the fuse then retested, nothing. When I turn the thermostat up, the led almost goes out, and you can hear it "bog down" like the transformer has a problem. is the circuit board junk??

 

[dave67fd]

4 flashes= high limit or roll out switch open.

The high limit switch has no adjustment. The roll out switch closes on temp rise. You can try to replace the fuse (with the correct size) and manually reset the roll out switch.

Confirm that you also have proper combustion air and that your vent isin't blocked.

got frustrated in just bought a new one.

Why didn't you call a service guy instead of buying a new one? Any new unit installed should have all the basic parameters checked like gas flow, manifold press. as well as making sure the line has been properly purged. Did you confirm your t-stat wiring/connections?

 

[horspla2003]

It was an exixting setup that has worked well, no changes. Everything is ok w the basics. I did a lot of testing and I think the circuit board is bad. I needed heat, so I didn't have time to wait. Calling a service place would have cost me more time and money just to be in the same position. T-stat is 2 wire and is ok.

 

[Sidekick]

I have a 45000 btu Mr. Heater on ng. It has worked good for a while. Went to use it this year, shuts down and get a 4 flash code, no blower operation either. Couldn't find anything wrong, got frustrated in just bought a new one. Swapped it out, new one ran for 10 minutes then quit well before it was up to temperature. It blew the 3 amp fuse in the circuit board. replace the fuse then retested, nothing. When I turn the thermostat up, the led almost goes out, and you can hear it "bog down" like the transformer has a problem. is the circuit board junk??

The heater you have installed has a very good track record if installed properly. The one main problem I have found over the years with homeowner installed units is that the home owner did not read where it says in the manual for a "Dedicated" lead shall be run. That means the heater should not share its circuit with any other appliances or powered equipment. Running such equipment on the same circuit will fry control boards very quickly. SO, make sure that the furnace is the only equipment on that circuit!

 

[curiousB]

The heater you have installed has a very good track record if installed properly. The one main problem I have found over the years with homeowner installed units is that the home owner did not read where it says in the manual for a "Dedicated" lead shall be run. That means the heater should not share its circuit with any other appliances or powered equipment. Running such equipment on the same circuit will fry control boards very quickly. SO, make sure that the furnace is the only equipment on that circuit!

I've had this unit running on a shared branch circuit with many others loads among them garage door openers with inductive loads for 3+ years. If the device is sensitive to other loads on the branch circuit it is a pretty lousy design.

 

[Sidekick]

read your manual- Most control boards are like computers - they do not take well to voltage spikes when a compressor in your garage refrigerator comes on or a skill saw starting.
Just sayin.

 

[CKC]

I had my Mr Heater Big Max 45 LP on a dedicated curcuit, It doesnt matter, mine will not stay lit tries to lite three times and faults, the original flame sensor was cleaned then changed out twice, now Mr Heater is sending a new board, should have bought the Modine it was $175.00 more, at this point so what!
When my new shop goes up, it will not have one of these in it....

 

[curiousB]

read your manual- Most control boards are like computers - they do not take well to voltage spikes when a compressor in your garage refrigerator comes on or a skill saw starting.
Just sayin.

I have. It doesn't say anything about a dedicated branch circuit. It only refers to protection and having a disconnect near the unit for servicing (i.e. a switch).

The heater itself has two separate inductive loads (blower motors) that will generate power supply spikes on startup. The logic board power supply has to be designed to exist in this environment. Its actually not very difficult to design for.

The OPs unit isn't failing due to branch circuit wiring. Its defective logic boards.

 

[Mr onetwo]

Just so you guys know....having a piece of heating equipment on anything but a dedicated (generally 15 amp) circuit is a code violation....your insurance company won't be happy if there is a fire involving your heater Also check your draft proving switch.

 

[Sidekick]

Just so you guys know....having a piece of heating equipment on anything but a dedicated (generally 15 amp) circuit is a code violation....your insurance company won't be happy if there is a fire involving your heater Also check your draft proving switch.

Thank you

 

[horspla2003]

I agree, if this is infact true, that is a crappy design. I have a board on the way, so we shall see. Thanks four the replies!

 

[horspla2003]

Well, it was the "logic board" on my unit. I replaced it with the updeated one that has a replaceable fuse on it and all is well. Thru my research online (take it for what it's worth to you) it seems that the boards are very failure prone. It seems to cause all sorts of wierd problems. Just throwing that out there incase anyone else happens to run across this in a search. :0)

 

[Chetter]

I had to replace the logic board on mine during the first season of use 3 years ago, mine would start the ignitor and it wouldn't stop even though the furnace was lit and running, turned out to be the board which they sent a replacement out asap and has been fine since. While I had them send the new board, the inducer blower was a little noisy, so I had them send a new one along with the new gaskets. All has been fine since. They are great heaters and I can't say enough about their service for me and would not hesitate to buy another Mr Heater product.

 

[regguy1]

I had to replace the logic board on mine during the first season of use 3 years ago, mine would start the ignitor and it wouldn't stop even though the furnace was lit and running, turned out to be the board which they sent a replacement out asap and has been fine since. While I had them send the new board, the inducer blower was a little noisy, so I had them send a new one along with the new gaskets. All has been fine since. They are great heaters and I can't say enough about their service for me and would not hesitate to buy another Mr Heater product.

I had a similar experience, first couple days it acted up. They sent a new board and alls well ever since (2 years)

You can see it in the video link below

 

[pro-team]

Hello everyone at the garage journal;;;;
having problems with flame sensorwould like to replace it could some one sent instrutions on how to re move it seem likee you have to take the whole furnace aprt to remove it gerry