Controlling furnace fan speed

[googleicq]

Here's one for all the furnace/electrician experts out there.

My mid-efficiency furnace has a fan that is too loud for me. Currently there are only two settings for the fan: On or Off.

I'd like to know if I (or someone else) can add a lower fan speed setting to the furnace fan OR failing that, have the fan changed for one that allows different settings (high, med. low for example).

I know a computer and a furnace are completely different animals, but I got to thinking about this when I learned you could control the fan speed of your computer/CPU/case fans with software.

Thanks!

[Speedy Jim]

Dig in there and find out what kind of motor. Is it a belt drive? If so, get a variable pulley.

Is it direct drive (motor is inside the fan)? If so, it may already have multispeed taps brought out.

[googleicq]

Thanks Jim, It sounds promising. I will look into it and see what I can discover. I might have to get a pro to check it out, but at least I know what things to look out for now.

Ric

[Joseph Meehan]

Having a pro check it out would be a good idea. Running a fan too slow can cause problems. Without knowing a lot more I would not be able to tell you if it would be good for your specific furnace. ("Knowing a lot more" refers to both more about your furnace and my personal need to know more.)

[googleicq]

Well I can't add much more so you won't "know a lot more" but here's a bit more info.

I just checked downstairs and it's a Lennox 'Whisper Heat' mid-efficiency furnace installed in 1998.

I haven't had a lot of luck with it so far. In Jan '03 the ignition module fried itself and needed a replacement. Then in Mar '04 the BCC board fried itself and needed a replacement.

Fortunately they were still covered under warranty.

[udarrell]

There may be ductwork issues resulting in excess noise, check out these HVAC pages:

[mm]

The seller of my house kept just about all the manuals** including the furnace manual, and it showed, or maybe it is the wiring diagram inside the removable furnace cover that showed, that the fan motor has

4 (or 3) taps.

I too thought the fan was too noisy, and wanted to run it slower. Unfortunately, the diagram showed the default fan tap as the slowest one, and when I got in there, I saw that that was indeed the tap in use.

As a last hope, I tried the other taps anyway, but indeed they ran the fan faster. Now I shut the door to my bedroom sometimes so I don't have to listen to it. There's room under and around the door for air to recirculate.

[CJT]

The fan speed needs to be what it is in order to move the appropriate amount of air. Mess with it and you can create other problems (e.g. furnace overheating or blowing cold air).