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Inline Duct Fans for cool room

7K views 4 replies 4 participants last post by  pjpjpjpj 
#1 ·
Hello, I have one bedroom in my 15 year old house that has a large window. I also live in Canada. The bedroom is a long ways from the furnace. It is colder than the other rooms. The room almost always has the door closed, and it has no cold air return (though the cold air return could change). My furnace is basic, no zones or anything, my thermostat is programmable, and I have no A/C.

Are the fans that they put inside the ducts/tubes, called inline duct fans, effective for someone in my situation?

This room that gets cold from the window also gets very hot in the summer with its West exposure. I was thinking the duct fan would also push cooler air into that room, when I leave the blower on.

Thanks, I'm a new user and newbie to HVAC.
 
#2 ·
Never used one, the they are available and here's some examples.

Have you tried to regulate the flow of air by adjusting the registers. Could you be loosing flow through leaky joints? There's a lot of options and possible solutions besides a fan. It's possible that the duct fan could cause other areas of the house to be cool. If you haven't done so, you could check with your HVAC person to check the air flow throughout the house and offer reasons/suggestions that would correct your situation.
 
#3 ·
Thanks, I've not contacted an HVAC person, and I really doubt that would help in this situtation. I fuss with the registers all the time. But the fact is that the room I'm concerned with has a very long run from the furnace, the furthest of all the rooms, the run also takes 2 90 degree turns and is located on the second story, the room has no cold air return. But the problem is more the room itself. The room is fairly small (13ft X 10 feet) but has a large window (6 ft by 6ft). The room's window faces West, and gets very hot in the summer (A/C is rare where I live - Alberta), and although the window is still relatively new, 15 years, it still keeps the room cold. (remember the winter temperature here in Canada is between 0 & 25 F) The room door is almost always kept closed (the room is rented to a roomate).


I've seen the inline fans mentioned, they are much cheaper than I thought. I suspect they make a lot of noise. But i'd like to know if anyone has any idea how the fan could be hooked to the furnace blower? I see that the device can use a thermostat, but since I don't have A/C the only way air moves is with the furnace blower on. Can the duct fan be linked to the blower for a switch? I use the blower in the summer to cool/circulate, but set it to auto in the winter so it only goes on when the furnace starts.
 
#4 ·
Hello CamL,
I do it all the time, a lot of homes around here, Mid Tenn, especacially multi-level, still have older furnace in the basement that need booster fans for heat and air.

There are a few way's to do it, depending on how much air you need, but a small booster would not need another t'stat to control it, as it would just
keep a few hundred CFM (cubic feet per minute) of air going into that room.
When the furnace was on, it'd get more heat, but when the furnace is off,
it just pulls from the rest of the house, a cheap damper could be the throttle to find where it works best, of course when it's bitter cold out,
you'll wnat it wide open, so, go for it, won't hurt, might help.
 
#5 ·
I bought an inline booster fan and installed it for a duct run to my master bedroom (up two floors, duct runs in exterior wall, has a bunch of turns, etc.). It works okay (the room now gets cool enough, but it's not exactly a gale-force wind blowing out of there!), and, as you suspected, it is noisy. The fan has a high-pitched whirring noise that you can hear on all floors.... I may go back and install some flexible duct before and after it to try to dampen the noise someday, but for the short time I have had it, I have gotten used to the noise.

I purchased a duct thermostat that was designed for this use. It has several switched options for running; off, always on, on for heat only, on for cool only. It attaches to the duct right by the fan, and senses the air moving in the duct from the push of the blower fan. I only need it for cooling (enough heat gets to my second floor bedroom simply from heat rising in the winter, and the one other grille in the room), so I set it for "cool only". When the tstat senses that the air in the duct is cold enough (there's a small adjustable screw for sensitivity setting), it turns on the fan. When the blower/AC cycles off, and the air in the duct warms up enough, the tstat shuts off the booster fan. In other words, it takes a few minutes of the AC running before it turns on, and then it runs for a few minutes after the AC cycles off.

It did come with instructions for how to wire it to the furnace, I believe, but I didn't want to bother.
 
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