Use of Oil System Fan When Piggybacking With Coal

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GeoPRR
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Post by GeoPRR » Wed. Jan. 21, 2009 4:48 pm

My existing oil-hot air system has three cold air returns, with a fan in the cold air return plenum, driving into the hot air plenum. Since this is wired to the oil thermostat, it does not run when the coal furnace is running, The existing coal furnace fan, attached to the furnace, drives warmed air into the hot air plenum. Although the coal furnace is rated way over the oil burner in BTU's (170,000 vs. 100,000), it dosn't heat the house as quickly as the oil setup does, nor does it reach the far corners as well. If I wired the oil fan, in the cold air return plenum, to run along with the regular coal fan when the coal thermo is calling for heat, will that solve my problem? Or am I missing something here in theory? House is two story plus basement, 140 years old, fair-good insulation. Some runs are fairly long.

 
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WNY
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Post by WNY » Wed. Jan. 21, 2009 5:37 pm

How is your furnace plumbed into your existing system? Post a couple pics, do you have the backdraft dampers to keep the flow going the right way when using your coal furnace.

have you adjusted the feed rate and hvae the coal setup correctly to get max BTU out of the stove.

And, Coal is slow at responding, it can take an hour to get up to temps.

 
TimV
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Location: Glens Falls NY Area
Hand Fed Coal Stove: Older Ashley Cabinet ( pre US Stove gobble up)
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Coal Size/Type: Warm weather smaller coal. Cold weather larger coal.
Other Heating: Oil Furnace Backup when repairs are needed

Post by TimV » Wed. Jan. 21, 2009 6:44 pm

If your oil furnace and your coal are on the same eletrical breaker I suppose you could just tap onto leads that supply your coal fan9at fan and limit) and jump them also to oil air fan and when coal got hot enough to start the coal fan it would run the oil fan and vica versa if you ran the oil unless you added an isolation switch.
If your hot air from coal goes into hot air side of oil furnace it would maybe be a good idea to 90 degree elbow the flow downstream of the oil furnace.
might not be "mostest best" way to do it but I cant see why it wont work .
I think you have eliminated the need for the backdrafat damper if it flows right. If it does back flow you only run heat around a circle and not really heating anything but what you are reheating in a circle.

 
GeoPRR
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Post by GeoPRR » Wed. Jan. 21, 2009 7:03 pm

Can't elbow the flow downstream of the oil furnace - I'm lucky I found any location to shoehorn the hot air duct from the coal furnace into the plenum. It travels about six feet dead horizontally from top of the coal furnace. Sorry, don't exactly know what you mean by backdraft dampers - where? Thanks for your interest.


 
TimV
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Posts: 312
Joined: Wed. Dec. 26, 2007 10:06 pm
Location: Glens Falls NY Area
Hand Fed Coal Stove: Older Ashley Cabinet ( pre US Stove gobble up)
Hand Fed Coal Furnace: Energy King 480 EK
Coal Size/Type: Warm weather smaller coal. Cold weather larger coal.
Other Heating: Oil Furnace Backup when repairs are needed

Post by TimV » Wed. Jan. 21, 2009 7:09 pm

They are dampers that go into the coal air return to stop the air flowing in the circle that actually makes it not recirculate...In other words just pusing air from one furnace to the other and not into the livingspace as intended.
But I think if you had both fans on at same time it would circulate ok

 
GeoPRR
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Post by GeoPRR » Wed. Jan. 21, 2009 7:33 pm

Just to be sure I understand you, did you mean "coal air return," as you posted, or was it a typo and you meant "cold air return"? Are you referrig to some separate coal system air return? If so, I don't see one. Te coal furnace seems to get its makeup air from the atmosphere around the exterior-mounted fan. On my furnace, it's mounted low on the rear, below the coal hopper. As to WNY's question about max BTU adjustment, I believe I've tinkered and tinkered until I'm burning as much coal as possible without dropping anything but ash into the pan. I'm going to make the two-fan wiring change and see what happens in that direction.

 
TimV
Member
Posts: 312
Joined: Wed. Dec. 26, 2007 10:06 pm
Location: Glens Falls NY Area
Hand Fed Coal Stove: Older Ashley Cabinet ( pre US Stove gobble up)
Hand Fed Coal Furnace: Energy King 480 EK
Coal Size/Type: Warm weather smaller coal. Cold weather larger coal.
Other Heating: Oil Furnace Backup when repairs are needed

Post by TimV » Thu. Jan. 22, 2009 8:18 pm

:D Its my typing!
I talked with a friend today and he said exactly as you described is how the first add on wood furnace he had was wired But hot air out his furnace went into the oil furnace cold air return as close to fan as you can install it. He said it worked very well

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