# Mr Heater Big Maxx/WiFi thermostat



## ofishloutdoorsman (May 15, 2002)

Installed a 125000 btu BigMax. Manual has wiring diagram for digital wifi thermostat, and watched a YouTube video of an install and use of a Honeywell thermostat, I purchased a Honeywell thermostat and installed it. The heater worked initially but then would go through the startup and would try to ignite but wouldn't fire. Customer support said, " they don't work well with wifi thermostats " try a conventional thermostat. So I did with the same issues, finally they sent a new motherboard. I tried the wifi thermostat and it worked initially but went back to problems, switched to conventional thermostat and so far working, although occasionally it still takes several attempts before it lights. Really want the convenience of the wifi thermostat but can't figure out why it won't work. Sorry so long, but has anybody had these issues? Thanks 

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## Plumman (Feb 11, 2013)

ofishloutdoorsman said:


> Installed a 125000 btu BigMax. Manual has wiring diagram for digital wifi thermostat, and watched a YouTube video of an install and use of a Honeywell thermostat, I purchased a Honeywell thermostat and installed it. The heater worked initially but then would go through the startup and would try to ignite but wouldn't fire. Customer support said, " they don't work well with wifi thermostats " try a conventional thermostat. So I did with the same issues, finally they sent a new motherboard. I tried the wifi thermostat and it worked initially but went back to problems, switched to conventional thermostat and so far working, although occasionally it still takes several attempts before it lights. Really want the convenience of the wifi thermostat but can't figure out why it won't work. Sorry so long, but has anybody had these issues? Thanks
> 
> Sent from my SM-G960U using Michigan Sportsman mobile app


I'm assumimg thus is a furnace that exhausts thru a plastic vent pipe? Did u follow the venting instructions to the letter as far as the correct size of the vent piping used and the total length of vent piping with the number of a elbows that are allowed. TheI thermostat doesnt have anything to do with the lighting sequence of the furnace. It just turns the furnace on like a light switch turns on a light. There are switches (pressure switches, flame sensors, plus other safety switches) that sense there is enough exhaust flow through furnace. If the exhaust and combustion air system isn't sized properly a little wind at the termination point outside will not allow the furnace light because the pressure switches sense that there isnt adequate flow through the furnace. Inadequate gas pressure and gas piping size will also affect a furnace lighting sequence. Is the furnace natural gas or propane. If propane was it converted from natural to propane. I recommend you get a service tech to get to the bottom of your problem.


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## 82shortbox (Jan 6, 2017)

Use the wifi stat to power a 24 volt relay and then the normally open contacts of the rely to close r to w on the furnace board. Sometimes the electronic board doesn't work well with electronic stats. Tech support said they don't work well with wifi stats. Sounds like you still have issues tho. Could be gas pressure, inlet or manifold, venting , or flame rod.


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## lewisg (Jun 28, 2006)

What does the IGNITION CONTROL LED flashes indicate? Like others have said the thermostat isn't your problem, it's simply is a switch that's either on or off. That's a HUGE heater, I heat our whole house (1500 sq. ft.) with a 49,000 BTU furnace. You must have an Amazon Warehouse to heat! <GRIN>. First guess from the explanation of your symptoms would be gas supply (manifold pressure) issues,
What's the gas supply size and length? 

Is it vented with a minimum 4 inch metal vent pipe?
Which way horizontal or vertical?

The IGNITION CONTROL LED will tell you everything you need to know.

Customer support is sandbagging you, I can see the wiring of a WIFI thermo in the manual.


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## ofishloutdoorsman (May 15, 2002)

There are no error codes indicated by the light on the motherboard. Not sure what size the supply line is, it was installed by the propane company. They teed off the tank for my house and ran about 200' of line to my 32x56x12 pole barn. I ran 3/4" pipe from heater out to regulator supplied by propane company, they set the water column pressure at the time of install. It is vented horizontally with 4" stainless vent pipe, one 90 degree elbow, approximately 6' of total pipe to termination tee. It worked when the propane guy left but not so much since.

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## lewisg (Jun 28, 2006)

No error codes would indicate there was no failure. Guessing you don't have a standing pilot light so if your furnace igniter does not activate within a couple of seconds, the flame sensor won’t detect the flame, and the controller will stop the furnace from starting. After the third attempt, your furnace will most likely go into a locked-out state. Is the problem consistent or intermitted? Have you actually watched the fire-up sequence to see what isn't happening when it should? Induce Fan Start> ~30 Second wait> Spark ignition> Solenoid valve opens Main Gas Valve> Ignition sensor proves the flame> Combustion process continues. If a flame is not detected within a10-second trial for ignition, the controller will try more two times before locking out. You kinda' gota' watch the whole event to see where it fails to narrow it down to some logical problem.


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## ofishloutdoorsman (May 15, 2002)

Update, I finally figured out the ignitor gap was way too big. When it sparked, the ignition was happening back at the mounting surface and not out at the tip. After adjusting, it fired the first time and has been working fine since, thanks everyone for the help. 

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