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Possible to upgrade single speed blower motor/squirrel cage to variable speed?

Possible to upgrade single speed blower motor/squirrel cage to variable speed?

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Old 07-07-13, 01:40 PM
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Possible to upgrade single speed blower motor/squirrel cage to variable speed?

Id love to get a completely new system but its not going to happen for a while, lack of that kind of money. House I moved into a few years ago has an old Luxaire system for heating/cooling. Currently, the blower motor only has one speed. And unfortunately, it doesnt push the air out strong/fast enough for cooling. It literally takes hours to cool my house down a degree or two. I can check that the air is cold coming out of the registers, but there doesnt seem to be a good/fast enough flow.

In the mean time, if possible, Id like to see if I can upgrade the motor/squirrel cage. If I understand correctly, the cage has to be specific for a certain motor. If its possible, any suggestions on how I can do this and where to get a good combo replacements?

Ive checked for duct leaks and fixed a few minor issues with them. Hasnt helped.
 
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Old 07-07-13, 01:49 PM
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the cage has to be specific for a certain motor.
There are a lot of parameters that need to be considered..... like mounting type, direction of rotation, shaft size, etc.

It's pretty rare that a company would have installed an undersized blower in their unit.
Maybe the unit is the correct size but you need more. It may not be possible based on existing room and space.

I'm guessing that all the filters are clean......right.

If maintenance was lacking in the filter department....you may have a partially clogged evaporator coil in your furnace and that would reduce air flow considerably.
 
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Old 07-07-13, 01:55 PM
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Its an old system as far as I know. And I wouldnt put it past whoever lived here before to not have something done correctly. When I moved in, they only had a few inches of decades old insulation in the attic.

I did clean the coils a couple years ago. Filters are clean/brand new. And this really isnt a new problem, its been like this since I moved in in 2010.

I guess I could see if I can get an AC guy to come out and give it a check up. Maybe they can test the airflow as well and Ill get their opinion on the blower motor speed. Unfortunately, I dont always trust some of these guys because they first and foremost want to get you to spend a ton more money. He'll try and talk me into an complete upgrade of everything Im sure.
 
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Old 07-07-13, 02:02 PM
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RPM is 1725 w 1/4 hp. Seems like it would be enough, house is small. But it sure isnt pushing air strong enough.
 
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Old 07-07-13, 03:01 PM
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I don't have any experience with belt drive blowers, but from what I know...

The way to increase the speed is to change the pulley size; it may or may not be adjustable.

The motor's horsepower rating may not be high enough to increase the speed. (can be confirmed by measuring the amp draw)

Either way it should be done by a tech who can verify that it's not moving enough air to begin with. Moving too much or too little air can cause problems.
 
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Old 07-07-13, 03:02 PM
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That is a large blower compared to some I've seen in newer units.

The motor spins at 1725 and the blower spins much slower.

To speed up your setup you would need a larger pulley on the motor and that might require an upgrade to the next higher fractional size hp motor.

You can determine the RPM of the blower. Put a mark on the motor pulley another mark on the blower pulley. See how many revolutions of motor pulley it takes to make one blower revolution.

It'll probably be 3-4 which would mean your blower is turning at closer to 500 RPM.
 
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Old 07-07-13, 03:07 PM
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Thanks for the replies. Guess the first thing Ill do is get an A/C tech to come look everything over and measure the air flow. Appreciate the help.
 
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Old 07-07-13, 06:42 PM
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Very few techs will carry an airflow meter in their truck so if that is what you want be sure to say so when you call for a technician.

From what I can see that IS an adjustable speed pulley on the motor but not a lot of adjustment to make the blower go faster. You could replace the motor with a multiple speed 1/3 horsepower and then play with the different speeds. You might be able to find a used motor in a hock shop or St. Vinnies or the like.

When used for heating how hot is the air coming from the registers? I don't need an accurate temperature as much as just a warm, hot, blistering hot description.
 
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Old 07-07-13, 09:33 PM
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Simply put, don't waste your money trying to do anything to that dinosaur, IMO. That furnace is AT LEAST 20 YEARS old and maybe more like 30 years old. It is long past its life expectancy! That aside, paying some one to try to do what you want could very well be a good down payment on a replacement (much more efficient) furnace. Being that you are in CT that could pay for itself.
 
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Old 07-08-13, 08:48 AM
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If there isn't one already, as others said, you need an adjustable pulley on the motor. Max speed is monitored by checking the amps and not exceeding the motor rating. Then to do it right, readjust for winter so it's slower for heating, based on temp across.
 
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