Changing a ac motor to dc motor for blower

[brdrbm]

Anyone ever attempt to replace a ac Blower motor with a dc controlled motor. I recently added ac to an exsisting warm air furnace. When we installed the ac we also changed the single speed (belt drive unit) to a two speed ac motor. The problem I have, while trying to increase air volume a larger pulley was installed. The two speed motor was lagging when it started, the amps were peaked out. So we tried a larger 1 hp 2 speed ac motor with cap start. This unit is ok, However when the fan starts the motor has a kick to it, this can be heard all throughout the house. So my next thought was a dc motor, They start smooth and stop smooth any thoughts from anyone.

[otto]

Variable frequency drive for the motor to allow it to ramp up and not start with such a kick, also referred to as a soft start. Not cheap but less expensive than converting to a DC motor and the rectifiers and all that mess.

[t527ed]

don't know if you could find a belt drive motor like you are talking about, if you did cost would be way high.:eek:

[danielworkerbee]

what brand of furnace and what year was it installed ? dan

[Airmechanical]

you might get lucky with a 1-h.p.variable speed motor
with the proper controller to ramp up speed slowly,

make sure the amp draw is within specs.

if it fails to work properly it WILL be an expensive experiment!

[Mr Bill]

if it fails to work properly it WILL be an expensive experiment!

You got that right all the VS stuff is a big seller right now until a few HO have to replace those VS motors "out of warranty" and the word about the cost gets out to there buddies, it will probably kill the VS stuff in about 5 to 10 years. Heck I went into the supply house the other day and just asked what one sells for for a particular unit heck I thought he was giving me the HO price and that included installation. :eek:

[seaeagle2]

What I've heard is that GE is buying a west german motor that is virtually bullet proof and what is normally failing is the brain box on the end, which costs much less than the whole assembly.

[amd]

Any residential furnace with a belt drive blower is probably 20+ years old and a good candidate for replacement. Do not blow hundred of dollars on a piece equipment which probably sends half of its heat up the chimney. (<= 60&#37; AFUE when new and properly tuned)

[otto]

Actually, you could rig a 2 pulley drive system.....or an adjustabl variable pitch that would adjust itself according to static pressure. Lennox did it in the 70's. Worked great, that's why they still make it....Oh, wait, they quit it.

Bah...........nevermind.

[neophytes serendipity]

It is probably cheaper to replace the furnace with a new one that has a variable speed drive motor in it.

An add on frequency drive would also work. You can get one on eBay if you know how it works and how to wire it up.

You could also add all the parts from a new variable speed drive furnace and "pimp" yours, but that will be way more expensive than the first option- replacement.

[Mr Bill]

Actually, you could rig a 2 pulley drive system.....or an adjustabl variable pitch that would adjust itself according to static pressure. Lennox did it in the 70's. Worked great, that's why they still make it....Oh, wait, they quit it. Bah...........nevermind.

Hey Otto what about a gear drive like a timing gear drive on a race car? :eek:

[mark beiser]

What I've heard is that GE is buying a west german motor that is virtually bullet proof and what is normally failing is the brain box on the end, which costs much less than the whole assembly.

In 13 years of working with equipment that has GE variable speed motors, I have never found one where the motor itself was bad, only bad modules.
Back in the ICM1 days the module was part of the motor housing, so you had to replace the whole thing.
Unfortunately it seems that many equipment distributors only stock the whole motor and module assembly, especially the ones that are relatively new to offering VS equipment. :(

In my area Trane and Carrier are the only ones I know of that have done the smart thing and stocked unprogramed modules and load the program for the specific equipment when you go in to pick it up.