how to modify the fan speed on my furnace (slow it down)?

[brute33]

I've got a bungalow that came with an oil furnace. 2 years ago I installed a wood pellet stove in the basement which i now heat with full time. To circulate the heat better I sometimes manually turn on the furnace fan. It works but the noise gets annoying. I'd like to be able to keep the furnace fan on all the time on low.

Anyone know if this is do-able? Do i need a furnace tech or an electrician? Anyone ever try this?

[MrBurns]

Some fans are multi speed, there MIGHT be a label/sticker on the side or somewhere instructing what to jump do change speeds. If you're not too sure, call the manufacturer or retailer with the model number.
If you're familiar with reading schematics and the fan has the capacity then it isn't all that hard but otherwise I'd say don't try it. Sounds like you want to keep it at a very low fan speed which you may not be able to do so with this one.

[Drthorne]

you'll need a 2 speed motor and the controls for it which will get complicated and expensive... or a variable speed controller and a 3phase motor which will be even more expensive.

[JAC]

Get your manual. On the furnace motherboard should be a series of jumpers that lets you control all aspects of speed control. (heat, a/c, always on, etc.)

[brute33]

the furnace i'm guessing is maybe 20-30 years old. i don't have a manual....

[loudsubz]

its doable just gotta search

http://www.controlres.com/ac.htm

[BuildingHomes]

the furnace i'm guessing is maybe 20-30 years old. i don't have a manual....

Ya I wouldn't fool with it then unless you may be in the market for a new furnace anyways. The motor may not have been designed for anything other than a specific voltage to drive it at. If you drive it too low the motor could stop and burn out the windings.

Just be careful I guess is what I am saying. You don't want to knock out your furnace now that the cold is here! :)

[Fraser River Rat]

I assume it is the blower fan noise that is annoying you. Are the drive pulleys held on with a lock screw? You may be able get a smaller diameter pulley for the motor &/or get a larger diameter pulley for the blower fan.

[Kanus]

You could probably slow the fan by changing pulleys but you have to be careful as slowing down the fan will increase the temperature of the air that's being delivered to your rooms.

[Pete_Coach]

You could probably slow the fan by changing pulleys but you have to be careful as slowing down the fan will increase the temperature of the air that's being delivered to your rooms.

How would that be?
OP, you need to check with a company knowledgeable about your brand of furnace. There are relays available that will slow down the speed of the motor on some brands. Others, it is not possible. Have your furnace inspected, cleaned and, serviced for whatever that costs (a good idea regardless) and while the guy is there ask him(or her).

[Kanus]

How would that be?


If you slow down the fan, you're reducing the airflow. The burner would continue to put out the same amount of heat as it's either on or off, so the air temperature would increase.