Forced air furnace question

I have a oil forced air furnace and am wondering if the fan control is set properly to go on and off with the best heat recovery efficiency?? What do others recommend to set the limits at. Currently I am at about 70 / 120 degrees for stop / start limits. Also wondering what the average furnace fan uses for kw in a day if on continuously. Thanks! Steve
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Consider any responses you get as WAGS because there are too many unknown variables in your post. It varies widely by brand, type, location of sensor, and several other things.
Right or wrong, here's how I did it. Feel the air coming from the registers. It should be warm when it comes on and still slightly warm when it goes off.
Check our furnace specs.
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the coller on and off the more efficent it is BUT, who wants a icey draft?
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My understanding (which could very well be way off base) is that the newer high-efficiency furnaces have heat exchangers that can not handle as much heat as the huge old clunkers could. Therefore the blower comes on way before the heat exchanger is at full temp to prevent damage. This results in an output of cooler air at the beginning and end of the heat cycle, with the blast at the beginning being the worst. Yes, the new models heat up faster and produce heat faster and therefore are more efficient, but you have to put up with that initial blast of cooler air.
Is this just an urban myth?
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IME, yes it is but I'm also far from any kind of expert on these matters. What does occur to me is, there is more than one heat sensor (actually if there's one, there's two) and sometimes 3 or more for the newer systems to keep all the factors in balance. There can be several stages to some of these systems. Any furnace designed to blow noticeably cold air wouldn't gain much of a reputation. Cool for a few seconds, as in evacuating the cool air from the ductwork is one thing but purposely blowing cold air is quite another one.
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Steve wrote:

I suspect 70 is too low. If you set your thermostat for 74, how would the fan ever go off? The intake air would be over 70.
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Thanks. I didn't mention in my OP that I also have a wood stove ducted into my furnace hot air plenum. The wood stove has a blower that pushes hot air into the plenum. The delema I've had with this is that when the furnace fan runs, it nearly overpowers the wood stove blower such that I need to really maintain a pretty hot wood fire to keep the air warm coming out of the registers. I have tried to power up the wood stove fan but then it seems to take the heat away from the wood stove too much and it becomes more of a cycling problem. Either I end up having to run the furnace fan continuously or shut it off completely. If I run the furnace fan continuously, usually in the coldest weather (below zero degrees F.), The house will stay fairly warm but in warmer weather above zero degrees F the house will get way too warm and I have to shut off the furnace fan completely. Thus its a continuous on or off cycle with the furnace fan switch. I was wondering if I could adjust the furnace fan limit switches so I wouldn't have to be shutting the furnace fan off/on so much. The oil furnace is a late 1970's model so I don't think the hotter plenum temps adversely affect the plenum when the furnace fan isn't running. Also, I wouldn't want to make any drastic changes to the oil furnace controls so it will run properly when we are not at home and no fire in the wood stove. Any ideas on what I could do to make this system work better would be helpful. Thanks again! Steve
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Steve wrote:

FWIW, I think my furnace fan uses approximately 10 KWH/D if run continuously. YMMV.
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