Fan for circulation problem


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I just installed a new Mr Heater Big Maxx 80000 btu furnace in my shop. I replaced a 35 year old Lennox furnace. Both are natural gas. The new unit works very well with one exception I cannot get the main fan to operate in the "circulation" mode. The manual is a bit vague however it clearly states the you use the green wire terminal on the thermostat connections to activate this feature. What it does not show is what do you connect the green wire to complete the circuit. Through much researching I have established that there is a standard for this. To use the fan for circulation you connect the green wire to the red wire using a normally open contact this completes the circuit. My Honeywell thermostat provide this exact function.

So here is the issue.... When I close the green wire connection the fan comes on and within a several seconds the gas valve comes on and now we are in the heat mode. Just for clarification the red -white connection is open and this time. I cannot get anywhere with the people at Mr Heater. Is it possibly a jumper needs to be set on the control board to make this mode work?
Something is wrong because the gas valve should not come on using just the green wire.

Thanks
JIm
 
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I think you need to consult for an HVAC contractor.
They may troubleshoot your problem.
 
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Thanks Jacob for your response.
There is no need for troubleshooting the unit has worked very well all winter. As I stated before the only issue is the circulation mode. You are suppose to be able to run just the fan with out the heater coming on. This is done using the green wire. My old furnace used the same wire color combinations. The people at MR Heater have no idea what I am even talking about so I presume this feature, even though it is in the manual, ever worked. I was hoping that other MR Heater using would share their experiences but no luck.

Thanks again
Jim
 
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Thanks Jacob for your response.
There is no need for troubleshooting the unit has worked very well all winter. As I stated before the only issue is the circulation mode. You are suppose to be able to run just the fan with out the heater coming on. This is done using the green wire. My old furnace used the same wire color combinations. The people at MR Heater have no idea what I am even talking about so I presume this feature, even though it is in the manual, ever worked. I was hoping that other MR Heater using would share their experiences but no luck.

Thanks again
Jim
Jim, for the time being could you put a simple switch in one of the lines to prevent the heater from engaging. This is a poor excuse for a solution but could temporarily solve the problem until you actually find the real culprit.
 
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Yes in the short term I could do that. Winter is coming to an end here I am going to leave things as they are. Maybe some other MR Heater users will come across this same issue and have a solution. If the people at Mr Heater would just take a minute and share with me what their design was suppose to do it would make this a lot easier. I have a feeling that what the book says and what it really does are two different things.
Thanks for the response and maybe I will hear you on the bands someday.
Jim
 

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