new duct booster


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Old 01-28-07, 10:04 AM
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new duct booster

My house is a 50 year old Cape Cod. The furnace is in the basement and the ducts are all rectangular and are run in the space between joists mostly. I am not getting good airflow upstairs, and I noticed that one of the ducts leading to the 2nd floor has a booster on it. It turns out this has been disconnected since before I moved in. When I reconnected it I found out why....it makes a horrible racket. I assume it is beyond repair and needs to be replaced, but I do not know where to find one like it. All I see when I search online are round duct fans. Does anyone know where I can get a good replacement, or if there is another alternative? The duct measurement is ~ 5"x12".
 
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Old 01-28-07, 12:09 PM
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Speaking as a homeowner handyman, that booster was installed because the previous owner failed to find out why the furnace blower was not delivering enough air flow. And if did, he did not want to go through the expense to correct it. If the furnace is over 30 years old, its time to think about replacing it and voice your concerns to the dealer/installer.
 
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Old 01-28-07, 05:11 PM
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That may be true for all I know, however I am not in a position to buy a whole new heating system either. All I want to do is replace the booster. It is an incredibly simple job to do, but I can't do it if I can't find the right part. That is all I am asking for help with.
 
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Old 01-28-07, 05:42 PM
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Don't waste your time or money! The fan will not solve your airflow issue
 
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Old 01-28-07, 05:52 PM
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Wink

ME TO : Forget that fan in the duct there. Work on some dampers in the duct and work on the blower. If the furnace is that old . Is it a belt drive kick up the speed . Or is it on high now? I dont see where you will get a fan to run in a 5"X 12" duct. Might find a squirrel cage kind to fit it
 
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Old 01-28-07, 06:36 PM
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scott68,

You likely won't get much support on replacing a duct booster fan from people who work in the heating industry.
They have a major design flaw in that the propeller fan they use is not meant to force air against a high static pressure which is what fans that force air through ducts do.
I personally have never installed one, only removed them when they either fail and block the duct or the homeowner wants a permanent solution.
These things are almost exclusively a diy fix so you should be able to find one at a place like HD.

If you wanted some help troubleshooting your system we could throw out some ideas.
Describe your system in detail if you want more.
 
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Old 01-29-07, 05:26 PM
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I'm obviously no expert...I'm barely even a novice. I am not really sure I understand the descriptions given but I'll try to explain what I have. The duct booster is not "in the vent", it is (or was since I removed it) attached to the outer wall of the vent. It may be the "squirrel cage" type if that is what you call it when it has what looks like a hamster wheel being rotated by an external electric motor. It was controlled by a line run directly from a switch in the heater, so it turns on whenever the main blower turns on.

The heater itself is a Heil oil fired furnance. Based on some documents the previous owner left, it appears to have been installed in 1981. The main ducts run down the middle of the basement (around 35' from one end to the other). The supply duct is ~ 8" x 16" and the return duct is ~ 8" x 14". The supply ducts to each room range from 3" x 10" to 5" x 12". The returns use the joist space so are ~ 9" x 14". There are 2 supply ducts in the living room, and 1 in every other room in the house. The kitchen and bathroom do not have a return. The 2nd floor did not have any returns either until I had them installed (by a local heating company). This didn't do much, but it did bring the temperatures in line a little bit. The 5" x 12" duct that had the booster on it supplies both the living room and one of the 2nd floor bedrooms. All of the ducts are pretty much in a straight line.

I have already had to replace the heater core in the furnace, my hot water heater (unrelated of course), and also had an a/c unit installed, so I am pretty much tapped out. Replacing the booster is about all I can afford at this point.
 
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Old 01-30-07, 02:53 AM
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Air flow to all registers will take the path of least resistance. Which means, most of it will go the first floor if they are not closed partially down. This will give you more airflow upstairs. This is the most common cause for insufficient airflow upstairs. Also furniture too close to the registers blocks circulation.
The next is dirty furnace air filter. They should be changed at least every six months.
Then we have to look at the furnace blower speed. If your handy, shut down the power to the furnace and check the furnace blower motor. Is the blower wheel, belt driven or is the blower wheel driven directly by the motor?
If belt driven, place the belt on the next biggest wheel at the motor end or the next smallest at the blower end. If the blower wheel is driven by the motor, check the wiring connections at the motor to see its marked low, medium and high. If a wire is going to the low connection, move it to the medium connection. This will increase the blower speed and give you some more airflow.
If you still want to replace the booster blower motor and/or wheel, check out the yellow pages. You should find a place that sells new or repaired motors.

But lets look at this a bit closer. All heating and airconditioning systems must be balanced to get sufficient airflow to every room. So if all registers are opened fully, the system is not balanced. But if your system is undersized, (it should'nt be) then it needs to be upgraded. Also, I see that you have two registers in the living room. Have you tried shuting one down completly?

The only other thing I can think of, is that if the thermostat is located in the living room and you have two registers, then the living room will warm up quicker then the rest of the house and your system will not cycle long enough to heat or cool the upstairs. So by partially shutting down these registers will send more airflow upstairs and allow heating and air conditioning to cycle longer.
These are things a handy person can do before calling in professional help.

There is just one thing thats not clear; is the booster blower wheel removed from the duct? this will interfere with air flow if not working. I can only guess that if the former owner installed it, it may not have been a recommended practive dispite the advertizing by manufacturers who do not manufacture whole house heating and cooling systems.

Also check to if you have dampers located in the ducts, if so, then adjust them.
Good luck.
 

Last edited by rjordan392; 01-30-07 at 03:07 AM.
 

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