Our master bedroom is always either cold in the winter or hot in the summer. The fact that the builder messed up by installing just one register in the room and the room itself is right above the garage doesn't help either.
Using a digital thermometer I was able to determine that the temperature of the air coming in was half that of the hottest register in the house (obviously this is for the winter case), and the airflow was barely there.
My solution was to install a booster fan.
The process was not all that complicated and this job can be accomplished by anyone with some basic electrical skills and some tools you can buy at local dollar store.
Was it worth it? The answer is YES. Can it be done better? Yes but not by much. I'm sure some people out there who are familiar with how a furnace works will be able to come up with a better way in regards to how to control the booster fan, like using a pressure switch or choose other outputs on the controller furnace board. In my case, I just went with what worked for me and what I felt was safe from a functional point of view and liability point of view.
If any good recommendations are made here (and they are easy to implement in my current setup) I will try to include them in the overall design for other users' benefit so feel free to contribute.
I should also mention that this installation deals with electricity and electrical connection which means you might need a permit but most of all YOU NEED TO PUT SAFETY FIRST also, don’t forget your safety goggles.
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Signing UpStep 1: The fan, the duct and what needs to happen
So here we go.
The booster fan is installed in line with the existing duct that goes to the register for which you want to increase the air flow. The fan I got has two speeds one for 200cfm and 300cfm.
The power to the fan has to be turned on and off when the furnace is on or off. In my case I used a relay that is energized by the controller board (will get into that later).
There are furnaces that have just one speed for the blower or more than one speed, they may also have separate connections for Heat and Cold (aka A/C). You will need to indentify which connection works best for you.
In my current configuration, the fan only comes on when the Heat is on. Eventually I will use a 2nd relay to power the fan when the A/C is on or maybe a presure switch but given that I can get a relay for $8 vs almost $40 for a pressure switch I think I'll go with a relay.
Optional you can install a regular switch to disable the fan in case it becomes noise later on, etc. It's just good to have it and it's not going to cost you more than $5 to do it anyway.
So in a nut shell, here is how it works, the furnace comes on and the inducer motor kicks in, after a set delay the blower motor starts up, as soon as that happens, the relay coil is energized and switches on the power to the fan. When the blower is turned off by the controller board the relay will also switch off the power to the fan.
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I don't know enough about the thermostat and the control board from the furnace/AC communicate. From your comment, it sounds like there is power control on a 24V circuit coming from the thermostat.
Please post some details, it might simplify my solution and make the idea more appealing to people who are not comfortable "tapping" into the furnace/AC control board.
Cold air from the AC is denser and not so easy to lift to upper rooms. Thus the higher fan speed
I compared the temperature to two other registers, one very close to the furnace and one a little closer to the furnace than the register in our bedroom. Here are the readings for the two:
- register very close to furnace: 122F/50C
- the other register 90F/32C
The last register (90F/32C) should be warmer than the one in our bedroom given that it is a shorter length and does not go through the space between the garage ceiling and bedroom floor.
I will update the Instructable with info re. performance.
I would like to add one of these booster fans to the heat duct as well as to the cold air return duct. ( I added a cold air return as there was none previously. However the pull is very weak).
Is it possible to connect both to the fan blower?
Thanks.
It sounds like you will have to use a separate blower for the cold air return but have both blowers turned on and off by the same relay.
I'm not sure you really need one for the cold air return. I suggest you talk to and HVAC guy and see what he says.
Maybe other people here can shed some light on this.
The cold air return that I added barely pulls at all, so it needs something to increase suction. Thats why I was thinking of a booster fan, in reverse.
Here is what it says on it:
JCWC-6128-1
Relay DC 110V 1P2T 20A QT BRKT (not sure about the B in BRKT) $7.50
Please note that it says DC so you might want/ to look for (or need) an AC one.
Where on earth, but more specifically in the GTA, can a mere mortal purchase the relay you used for this project? Or its equivalent?
Eastern Refrigeration won't sell it to me because I'm not an HVAC tradesman.
WWG Totaline won't sell it to me for the same reason.
Seriously, I'm standing there looking at it, cash in hand, and...no sale. I couldn't even grease the guy. I'm assuming it's not some critical component in a nuclear device, so what's the problem I wonder.
Ebay sellers want US$30 just to ship it to me so I'm trying to avoid that route. Certainly someone in the GTA can supply this to a DIYer.
I've also tried Westburne-Ruddy, Nedco, and TES. No luck.
Thanks for any help. Other than the relay, I'm ready to go.
Your best bet would be to go to Sayal (http://www.sayal.com) and go to their relay section. I got 3 relays from the Matheson Blvd. and Dixie Rd. store for about $7-8 about 3 week ago. They have lots of them. Your biggest problem will be finding the one you want. They have one aisle just for relays 5V, 6V, 12V, 115V, 240V etc. They also have solid state relays but they are more expensive and for this kind of application it doesn't make sense to use them. While you are at Sayal look for quick connect terminals, shrink tubing etc. You should buy 2 relays (heat and cold) and be done with it. When I did mine I wasn't sure how the whole thing was going to work out. Next year I'll do the cold relay as well.
Let me know if you need help, I work 10 mins from Matheson and Dixie.
Sayal has a store in Vaughan as well (check out their locations on their site), that one is 10 mins from where I live.
Couldn't you just drive the booster fan from the HUM connection point? Isn't it only energized with 115V when the blower motor is on?
1. My controller has separate outputs for Heat and Cold and from what I'd read it sounded like there are separate windings in the blower motor (2 different speeds I guess). Later on, this will allow me to install a second relay that will be energized by the Cold circuit, that way, my fan will kick in when the AC is on as well.
2. Liability, if my fan is totally separated from the control board via a relay, then I don't have to worry about it damaging the control board if something happens on the fan side.
Also, the relay option will allow other people to control fans that are not 115V, say 24V. Obviously they will have to use a separate transformer or use the one that's already in the furnace but from a control point of view, using the relay keeps things segregated and safe.