how quickly can a furnace raise house temp 20F?

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Just had the blower motor replaced on our York furnace this morning. Outside temps were 20F today with some wind. The new motor was assigned the task of warming the house from 45F to 65F. This took it 7 hours, which seems like a long time.
How many degrees per hour is a usual rate of temperature rise for gas forced-air furnace?
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KLS wrote:

2(+/-) F/hr unless _WAY_ oversized would be pretty typical....you're about right sounds like.
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I guess mine is way oversize, i can pick up easily 10 degrees per 1/2 hour. I have the unoccupied downstairs set to 55 over night, & brought up to 68 at 6:30 am. I've never seen it not make 68 by 7:00 even when it is in the 20s outside.
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On Sun, 25 Jan 2009 19:30:24 -0800 (PST), Eric in North TX

The length of time the temp was low makes a difference. The thermal mass of the structure and contents make a diference that becomes greater if it has all chilled to match the lower temps. That stuff takes a long time to heat back up.
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On Mon, 26 Jan 2009 06:21:32 -0500, snipped-for-privacy@dog.com wrote:

Yes, the house was chilled for probably 12 hours (the motor died overnight, and the outdoor temps at that point were single digits). House was built in 1930, 2 floors, has numerous windows, full basement, full attic, not well insulated, but has storm doors and windows all around. Furnace is a York 2-stage Diamond Deluxe 95, installed in 2003. We live by Lake Ontario. But this new motor doesn't seem to be heating up as quickly as the previous one did; the old one used to be able to get the house from 60F to 65F in an hour, and we're still not up to temperature 1.5 hours later this morning, so I'll be calling the HVAC company to check this.
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wrote:

Measure the input and output temps of the unit while it is firing and blowing. Are they within the specification listed in the installation manual?
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Eric in North TX wrote:

Hmm, Oversized furnace won't be very efficient.
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wrote:

-snip-
No- but if it gets to 30 below then the furnace is designed for a 100 degree temp difference. By design, when it is 20 out the furnace is double the size it needs to be. But most of us have just one furnace. [and those of us with 30 yr old furnaces probably only have one fan speed]
Jim [and to save anyone the trouble of posting 'you should replace that old beast' - Maybe I will someday, but it tests at 85%, I know all of its *very simple* parts intimately & I only burn 400 gallons of oil a yr so I'm not in a rush]
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a better question is why would one want to raise temperature 20 degrees?
if your leaving the home cool to save energy thats good.
the OP could add some extra heating like a couple gas wall heaters on a master timer switch to help reheat when you arrive home fast.turn knob trips on extra heat for 30 minutes to help with re heat
new furnaces are sized for efficency and lack the BTUs to raise the home fast.
adding a wall heater or other gas heater solves that and is a nice back up if your main heating plant fails
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On Wed, 28 Jan 2009 06:25:03 -0800 (PST), " snipped-for-privacy@aol.com"

The OP (that would be me) had a furnace DIE last weekend. The house temp dropped 20F as a result. I don't believe that installing various other heating devices would have been the cost-effective solution to my essential problem of not having central heat.
Those of you who have been paying attention will be jubilant to know that my repaired furnace now is back to raising the house temp 5 degrees in an hour, as it used to. Whew!
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wrote:

That's why I installed a 2 stage furnace. So far it has not been cold enough long enough to require the furnace to run on the high BTU setting (only had it 6? years now)
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Depends, Mine is a 96% efficient model, computer controlled. The exhaust is so cool they use PVC to plumb it. I can't see how an undersized one running 24-7 at max capacity could top mine cycling as intended. I've got a 5 ton heating and cooling about 2k fairly well insulated sq ft. My only complaint is; it is a bit noisy on the intake side.
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A minor quibble: 20 degrees in 7 hours is (much closer to) 3 degrees per hour. -- H
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You're joking, right? You expect somebody to give you a figure without knowing the size of your furnace or the size of house?
Hint: a twenty million BTU furnace is going to warm a dollhouse a bit faster than a bic lighter will warm up the taj mahal.
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KLS wrote:

It depends.
steve
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KLS wrote:

FWIW, I have my programmable thermostat set to let the house cool about 5 degrees during the day when I'm not here, and I think it takes about an hour to bring it back up to temp, so I would say 4-5 degrees per hour isn't unreasonable. Your experience seems to be in the ballpark, particularly given the cold outdoor temperature. As the other posters have pointed out, there are many variables involved -- furnace size, house size, insulation effectiveness, outdoor temperature, etc.
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There are many factors. Size of furnace, insulation, number of windows, day or night, opening of the door, amount and type of furnishings, etc. No one can say for sure without a lot of calculations, but that does not seem unreasonable. There was a lot of sensible heat lost that has to be replaced and that takes a lot of time..
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I turn my heat off at nights and when we are not home. If it is 60 in the house, it takes about an hour to warm it up to 72. If it takes 7 hours to warm your house that much, I would wonder if your insulation is particularly poor or if your furnace is undersized.
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3 minutes.
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If this is gas or propane fuel, windows are excellent and insulation is right, then that is a long time. However, if you have a heat pump, that sounds about right. Activate the emergency heat option which will use the resistive heat strips and watch your electric meter whirl.

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