fantec inline duct fan for ac boost

19 years ago

Does anyone have any experience with this product? We are looking at having a central a/c unit installed for a 35 year old 2 story house with the bedrooms upstairs. Our house sits on a concrete slab where the furnace ducts were actually put into the slab when it was built. Thus the air from the heater (and new ac) is forced downwards before it makes it out to the registars. The a/c for the upstairs would thus have to go down then all the way up to the attic then out the upstairs registers. Every ac guy who has come out has told us that we won't get a bunch of cold air upstairs because of the distance it has to travel and the physics of cold air trying to get up through the hot air. Then this last guy told us about the fantec fan which gets installed into the duct going upstairs which would boost the air outflow up there. The extra cost for this is $650 installed, so it is not cheap. But, the bedrooms are probably where we really would like the ac so it is not unbearable to sleep at night. I'm wondering if this thing really works like he says it does.

Thanks

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Comments (10)

bob_brown
19 years ago
Hello,
The first attempt to correct the problem would be more insulation on the duct. If this does not work a duct booster may be in order.

When using a duct booster, you will draw more air thru the duct, and reduce air available to other ducts. As a remedial fix, this will work, but will affect other rooms. If the duct is otherwise restricted it may work.

As to the cost, the average duct fan cost less than $100. If you have flex duct, this is a simple job. Cut the duct, and splice the fan into the 2 halves of the duct. The fan then needs 110vac. I would probably test the airflow before making the fan permanently on. You may use a night switch to control the fan.
mr_havac
19 years ago
Bob Brown, did you read this post before you went and answered it. They said the ducts are "imbedded" in the concrete slab. MORE INSULATION????? And the fan he is talking about vs. the fan you are talking about are apples to oranges.
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bob_brown
19 years ago
Mr HVAC made a valid point in his attempt to slam me. Where is the fan mounted. When one says duct fan, one assumes the fan goes in the duct. When I Googled Fantec, I found the company, but could not download the selection guide. Does the fan mounts in the duct in the concrete, or inside of the duct to the second floor?
mathdan
Original Author
19 years ago
from what I understand, it would go into the duct which is heading upstairs. This is a 10 inch duct. The idea is to get more air upstairs . Maybe this will help. Imagine drawing a U with a line through it horizontally. The air would start in the top right corner of the U then go down past the line (concrete floor)then up the left side on the way to the attic and thus upstairs. The fan would be placed into this left side of the U to help get the air upstairs.
Dan
bama_dude
19 years ago
Mathdan,I have used several fantech fans in many different sizes.They are built well and I have not had any problems at all with them.
airsome
19 years ago
Fantech makes a great product. They are one of the few (if not the only) that apply commercial quality to residential apps. You can by duct booster fans at HD, but they produce almost no additional boost because they are axial, and because they are no larger in diameter than the duct. They are like little desk fans. Fantechs are blowers (squirrel cage).
That being said, I believe you will never be satisfied with any kind of adaptation to your existing duct. I strongly suggest finding a contractor/dealer who will rework your entire duct system. Expensive? Yes. Find the best one.
mr_havac
19 years ago
"Mr HVAC made a valid point in his attempt to slam me'
I'm not trying to slam you bob, but you should read and think before you type, that's all.
A good technician fully pays attention to what the customer is explaining.
bob_brown
19 years ago
Once again MR HVAC is a slammin and a dammin before reading the post. I did not describe the type of fan originally. All that I said was you need good insulation first, then the fan is put inline with the duct. This did not describe the type of fan used. The cheap axial fans are about $30. I said less than $100. This should give a clue that I was allowing for several types of fans. There are better and worse axial fans. There are also very expensive squirrel cage fans. This is the reason I gave the dollar allowance. The insulation is most important. This is what I said. I did read the post. I did not talk about static pressure, because I did not want to confuse the discussion. I did talk about starving the system if too much fan is used. Unfortantly both of you did not read the original post or my posts very well. One would have to assume the duct was already in place for the heat. IMO, better designed systems discharge heat from the bottom and cool from the top. My system was designed that way in 1970. The theory is not to damage the refrigeration coil with the heat.

When I have to explain every statement to experts, I wonder about your skill level. You don't look so good right now. We all make mistakes, but to make a mistake trying to slam someone is worse than normal.
hald
19 years ago
I have had a fantech 6" duct fan ventilating my guest bathroom for several years now. It is quiet and powerful. It has never been a problem and still works as good as new. I think Fantech makes an excellent product.
Hal
actech180
19 years ago
Well, I rarely ever recommend installing an inline duct booster, since frankly a system is designed to output a specific amount of airflow with a certain amount of static pressure. My first suggestion is always to re-configure the duct system if at all possible. I understand that your situation is unique, given that your ducting is embedded in concrete. From what youve described to me, a ten inch duct is way too small to service the upstairs portion of your house, and if there is any possible way to increase the size of that supply, I would explore that option, even if you could only increase the part not embedded. Then put the booster fan in the system to help the unit overcome the challenge of travel distance and static pressure. If possible, damper the downstairs vents a little to force more air upstairs during the summer.