Oil Furnace And Blower Turns On By Itself (Even With No Thermostat Connected)

John's Avatar (by Gravatar) by John in  Climate Control » Heating 

I attached an image of the furnace which displays the model number and other information on the tags. The model numbers I can find are:
Beckett AFG Oil Burner
Honeywell RTH6580WF1001/W Thermostat
Honeywell R7284B1024 Electronic Oil Primary

My oil furnace will run normal most days doing the following:
1. We wake up and turn the thermostat up to 72F
2. The furnace heats the house as expected to 72F
3. The house will drop a few degrees and the furnace will kick on to get it back to 72F

This happens every few days, sometimes multiple times in one day:
4. After completing step 3 a few time, the furnace will turn on by itself (blower and heat/flame)
5. When this happens the temperature in the house will already be 72F (or possibly 73F)
6. It will run for 1-2 minutes, then all power to the furnace and thermostat will be lost (just like if I turn off the emergency switch)
7. It will continue to happen even if I turn the thermostat to the off position OR remove the thermostat from the wall
8. We have an electric exhaust fan, so when the power is lost the fan does not continue to spin and exhaust fumes build in the basement (slowly though since it is only running for a couple minutes, but sometimes we don't notice the issue for hours)

To solve the problem:
9. I turn off the emergency switch and let the unit sit for a few hours
10. I turn the switch back on and everything will work properly for hours or days

Other notes:
11. The unit never goes into lockout
12. Everything has been preffesionally serviced/cleaned at the end of the last heating season
13. I have had 3 techs from 3 different companies look at it and they are not sure what the problem is (although none of them have tested any parts or been in the house while the problem is happening)
14. I have forced hot air with air conditioning
15. The furnace has a 24V transformer and my thermostat requires 24V
16. Last year we were having a lockout issue, the first tech changed the pump and then the second tech changed the primary (changing the primary resolved the issue and the oil furnace ran perfect for the rest of the season)
17. We have an electric water heater, so the furnace is only used to heat the house

click to open the full size version of the image
click to open the full size version of the image

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Answer by

Rumor has it that the Honeywell Protectorelay/Controller/Primary boxes have questionable soldering or quality control and are becoming known to fail in as little as a couple of months...so get another or another brand of Protectorelay/Controller/Primary box. On the flip side, your Motor may be starting to fail and is sending an intermittent fault to the Protectorelay/Controller/Primary box and being the actual root of the problem.

Answer by

It's probably the Honeywell Protectorelay/Controller/Primary. New doesn't mean much with them having poor soldering or quality control. Or, the Motor's going bad and faulting out the Protectorelay/Controller/Primary. Replace both and see if everything's good for years, as it should be. It can't be any worse than what you have now.

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