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Old 12-10-2011, 10:05 AM   #1
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Strange oil furnace problem: blower comes on before burner


Hi All,

Question regarding the oil burning furnace in our new (to us) home.

I'm seeing this strange behavior: the furnace will turn on for about 2 minutes, then shutoff, even if the thermostat is calling for more heat (i.e. thermostat set to 70, room temperature is only 58). Instead of running continuously until getting the house is up to temperature, the furnace cycles periodically in this fashion until, after a few hours the temperature is finally reached, but it takes quite a while.

After a little closer looking and listening, it appears that the blower and the burner actually come on in the wrong order. First the blower starts, slowly turning over, then gets up to speed. 30 seconds later the burner itself turns on. Then 60-70 seconds after first coming on, the blower turns off, while the burner continues to run for another 30 seconds (i.e. it's on for about 1 minute).

First off, isn't this the wrong order? Shouldn't the burner come on first, and then the blower? Is it possible for the two units to be wired in reverse? If they are, then I'm concerned about the burner running without the blower in that fashion, since it's shutting off due to a temperature sensor, and not the thermostat.

A local oil company serviceman came a couple weeks ago to replace the ignition coil, and hearing the blower shut off so quickly, assumed that the blower was overheating and replaced the blower, but despite his claims the problem didn't go away.

Can anyone give me some insight into where to start looking into the issue? Can folks confirm that this behavior is not right? The burner is an Beckett AFG, and the oil primary is a Honeywell R8184.

BTW, I asked this question at another forum, but the only responses I got were "call a more competent serviceman" which while reasonable was not what I was asking.
Thanks,
Rob

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Old 12-10-2011, 11:09 AM   #2
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Strange oil furnace problem: blower comes on before burner


post the brand name and model of the furnace and some pics of it. does it have any other accessories like a wood burning stove or heat pump attached to it.

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Old 12-10-2011, 11:59 AM   #3
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Strange oil furnace problem: blower comes on before burner


your right on the fan after the burner heats up the exchanger either from a control module time delay or a metal heat disc closing from the heat.if you have AC does the fan run hi from the stat in ON/FAN only? when the guy did the motor did he change the capacitor with new motor..might be the slow motor problem...hold that invoice $$$ for a call back to the service company on that one to pick there motor up or eat the bill......... lets hear back
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Old 12-10-2011, 07:58 PM   #4
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Strange oil furnace problem: blower comes on before burner


Stat calls for heat.Burner comes on.Either a timer or a heat sensing relay (i.e. a fan and limit control) senses eno0ugh time or tempature and signals the blower to come on.Stat is satisfied and opens the low voltage circut.The timer or the temp sensor feels the heat till it cools off a bit then it opens the line voltage blower circut and fan stops.,,,,,,,,,,,That is what should happen.
I have no way of knowing but it sounds like the man that changed out the motor miss wired it into the fan and limit if thats what you have.
You cannot run it the way it is,the burner on with no blower will overheat your unit ,blow a limit,and eventually crack your heat exchanger.
Good luck
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Old 12-12-2011, 10:41 AM   #5
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Strange oil furnace problem: blower comes on before burner


More details on the oil furnace.

It seems to be a basic, no frills, no-name brand. The energy guide lists it as a "Metzger Machine Corp Series 12A". There's no external branding except for a "Made in USA" sticker. It's green :-> Photos attached.

No AC, wood burner, heat pump, or any extras.

The capacitor was replaced along with the blower motor.

The specific parts are

- Beckett AFG oil burner
- Honeywell R8184 oil primary.
- Honeywell R8285A control center
- The blower motor is a Marathon X009 (048A110787A)

A
Both the new blower motor and the old seems to have the same fundamental issue, in that the blower comes on before the burner.

Thanks!

Rob
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Old 12-12-2011, 12:04 PM   #6
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Strange oil furnace problem: blower comes on before burner


blower might be working off a time delay is it the last thing o go off after the stat satisfies...if it does then there must be a heat DISC that opens after the HEAT-X cools off..first off pull the stat and jump R to W for a straight heat call then work that emergency switch on the side to check that fan startup vs burner...if you have no control panel within that boiler has to be heat activated fan ON...that honeywell relay might be the fan relay wondering...here is what a thermal fan limit disc looks like... http://www.bestbuyheatingandaircondi...ry_Code=fl-tdf if even that new motor and cap are installed as original...something is making it crap out and the burner will trip hi limit fan will cool it down then fire back up and just repeat that cycle the fan is randomly running.. furnace burne is reacting to no air moving the heat out up into the space...

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Old 12-12-2011, 02:55 PM   #7
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Strange oil furnace problem: blower comes on before burner


Look,you listed the controls on your furnace,but none of the listed controls have anything to do with the blower.
I believe that control is under the panel above the burner,if not follow the blower mtr wires back to some kind of control.
Either that control is bad or the man miss wired the motor at that control.
It almost sounds like he wired the motor into the limit side of the control but I don't know that without seeing the control and how it is wired.

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