Furnace Fan "auto" vs "ON"

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Furnace fan can be set to "auto" and "ON", I ususally keeps it on the "auto"
I think when you keep the fan "ON" the fan will run contineously while on "auto" it will start and stop automatically as per the need.
Does anyone know which weather condition you should keep the fan to "ON"? Thanks in advance.
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I've had my fan switch set to 'on' for the last 15 years. Costs a little more than a 100 watt light bulb to run, but stopping and starting is worse for an air cooled motor than leaving it on. Make sure you keep the air filter clean. You'll sleep better, and the temperatures will be more even.

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Bob wrote:

Are you sure about that? I think mine draws about 5 amps.
but stopping and starting is worse

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I think leaving the blower running 24/7 will wear out the bearings much faster and use electricity...
leave it on AUTO unless you need the added ventilation.
Mark
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I tend to leave the fan running continuosly more in the summer time than in the winter. But I think the motor draws more juice than a 100W light bulb. If you have a 3/4HP blower at the very least it uses 5 amps.
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And the filter will need cleaning more often.

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wrote:

That I suppose would mean that the air in the house is cleaner.
But only a little bit
I always leave mine on auto. These are mattters of taste, and De gustibus, no est disputandum (or something like that: There is no disputing with regard to taste.) but I don't care if there are minor variations in temperature, and I like the silence when the fan is off altoghether. It would drive me crazy to have it on all the time.r.

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wrote:

A constant noise is less distracting than one that changes (on and off) unpredictably.
BTW, I remember spending the night with someone who left the fan on all the time, and the room I slept in was next to the furnace. I never noticed the fan after a few minutes except once. That time, it was a power failure.

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wrote:

non est disputandum.

To some people.
This is a matter of taste.
This I really can't spell: Chaque a sangue. Each to his own taste.

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wrote:

Chacon a son gout (there's an accent over the "a" that I'm incapable of placing).
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It depends on your motor. Mine is 1.2 amps.
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Bob wrote:

How many HP is your blower?
Are you sure your not referring to the combustion blower motor?
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Ive got a 1/2HP on mine, its pulling about the same...but then, load, due to the duct design, will play into this, and most people do not clamp a meter on, close the door, and take a peak reading with the blower under load.

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The last 2, 100000 btu furnaces Ive had pull apx 375 watts on a direct drive blower. that will cost anyone at .125kwh a standard US rate apx 35$ a month run 24x7. That is a bit of a waste. No furnace blower ive seen can pull only 1.2a under load. I think you are measuring it wrong.
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They make direct drive blower motors that draw less than 1 amp at 230 volts, but I've never seen a 115 volt motor on a furnace that low.

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I used a plug-in meter (kill-a-watt) on the furnace power cord, when I read 6.9A.
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Mark Lloyd wrote:

Let''s look at it this way:
Ideally, 1hp = 746watts
If a motor delivers 1/2 hp, then its actual wattage will run over half of this, because the motor isn't 100% efficient at converting electrical energy into useful mechanical energy.
A half horse blower motor consumes about 400 watts.
On low speed, however, at 230 volt, the amperage draw can run down around the 1.2 amp region.
On many newer units continuous fan is defaulted to low speed, which is equivalent to about 1/2 the rate hp of the motor. IOW, on low speed a half horse motor will be running at closer to 1/4 hp, or thereabouts, or somewhere in the region of 200 watts, and the amp draw corresponding to this on 230 volts is down around the 1 amp mark. I've seen them running under 1 amp.
hvacrmedic
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My (gas) furnace consumes .14A with the fan off. 6.9A with it on. That's with no heat.

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LOL! Bob, you're either leaving out some relevant facts, or you're lying, I'm not sure which! Also, most fan motors aren't continuous duty in the way you're claiming to use them.
What's missing from your post? Or are you just full of it?
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: > Furnace fan can be set to "auto" and "ON", I ususally keeps it on the : > "auto" : > : > I think when you keep the fan "ON" the fan will run contineously while : > on "auto" it will start and stop automatically as per the need. : > : > Does anyone know which weather condition you should keep the fan to : > "ON"? Thanks in advance. : > : :
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Air-cooled direct-drive blower motors can be run all the time, but you should have a properly sized duct system, and keep your filter clean. It's much worse to stop and start them all the time. Once those motors get going, they have very little strain on them.

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