Mr. Heater Big Maxx problem

[bdk1976]

My Big Maxx 45k propane heater has started giving me some problems after two years of trouble free service.

When the thermostat turns turns it on, the exhaust fan comes on, the ignitor starts, and a strong blue flame is visible into each of the tubes, but after about 10 seconds (a couple of seconds after the ignitor stops), the flames go out. It almost seems like the propane is 'switched off' at this time.

I've tried two different thermostats, as well as jumpering the two thermostat wires together with the same results each time. I've also tried to reset it by cutting power all 110v power to the unit as well. Plenty of propane in the tank and propane seems to be getting through fine as evidenced by the strong flames each time it tries to come on.

The green light gives me a steady flash - it doesn't seem to be throwing any codes that are listed in the manual.

Anybody else encounter a problem like this?

 

[twostory]

First, I would call Mr Heater and ask them what is wrong.

My guess on what is wrong:

There is a flame sensor that decides if the flame is burning. If this sensor is not working, the gas value would problaby turn the gas off once the ignitor stops sparking.

 

[Junkman]

I am not certain what type of flame sensor that they use, but if it is a photo cell, then it might just need to be cleaned. Possible that it has soot on it, or a spider might have built a web across it. Should be easy to see once you get your ladder out and take the side cover off.

 

[83trekker]

ley us know

 

[Bustawrench]

My Big Maxx 45k propane heater has started giving me some problems after two years of trouble free service.

When the thermostat turns turns it on, the exhaust fan comes on, the ignitor starts, and a strong blue flame is visible into each of the tubes, but after about 10 seconds (a couple of seconds after the ignitor stops), the flames go out. It almost seems like the propane is 'switched off' at this time.

I've tried two different thermostats, as well as jumpering the two thermostat wires together with the same results each time. I've also tried to reset it by cutting power all 110v power to the unit as well. Plenty of propane in the tank and propane seems to be getting through fine as evidenced by the strong flames each time it tries to come on.

The green light gives me a steady flash - it doesn't seem to be throwing any codes that are listed in the manual.

Anybody else encounter a problem like this?

Sounds like a flame rectification problem to me.

Make sure the unit has a good ground connection all the way back to the service panel. If so, it's time to call for service. Could be a dirty/defective flame rod, bad wire or the ignition module could be on the way out.

 

[krooser]

Not sure about the new furnaces but older ones have a thermo-couple that sense the heaqt from the burner...no heat it shuts down the gas. I used to have to physically wipe down my thermo-couple every fall to get it to work properly.

 

[Bustawrench]

On second thought............try pulling the hose off the pressure switch ports and cleaning out the ******* with a paper clip, sometimes they will get gunked up and do exactly what you are describing.

 

[bdk1976]

Thanks for all the replies - I was able to climb up there today and take a closer look and do some troubleshooting. As a couple of you mentioned, things are pointing to a faulty temp sensor. I went ahead and ordered replacements (about $10, with shipping being most of the cost) and will try those out and go from there.