HVAC Duct Booster Fan

[jade97]

Good Afternoon!

I have a 2800-3000 sq ft Ranch Style home with a heat pump. When we moved in in 2015, we found the MB to be excessively colder than the rest of the house, so the builder added a booster fan. It does fix the heat issue (on a switch to turn it off in the summer), but I cannot get the fans to last more than 2-3 years. What happens is the fan gets very noisy...this one sounds like something gets stuck in it, groan stops & starts...then runs normally. I'm guessing it has to do with the bearings?

Is there another solution or a good brand to use? It is a 10" duct.

 

[chinboys]

If you can access the booster fan easily then I would build a box for it where I can open a door and be able to clean or oil the bearings of the unit.

I like the brand Fantec inline duct fans. They are expensive but my 6-inch diameter dryer unit still works after 5 years of use.

 

[Higgins]

My daughter had he same problem. found a fan register unit that replaced the existing register and loves it!

I'm also going to purchase the same unit, im just up to my eyeball's in alligators and other things have a higher priority!

AL

 

[75gmck25]

We had a similar issue with our master bath, and the final fix was to run a separate larger duct off of the main plenum and directly to the bathroon. Its still a long run (goes up and over a cathedral ceiling in the MBR), but gets much better flow from the main HVAC fan.

Bruce

 

[yeldogt]

The solution is a larger duct ... but, I'm assuming this is not possible.

The fantech inline fans are the best and run forever

 

[jade97]

Thank you for the replies!

I am not sure what brand it is. I no longer have the box. It was purchased at the local supply house my builder used.

As for changing the duct size, it is not doable. Maybe I could draw out the layout at some point.

Think of this house as a large rectangle and the master bedroom and bathroom is a separate rectangle on the back corner. Out of the furnace the duct to the master "wing" runs inside the floor joists and has a steel beam, so it can't hang below joist (25-30 ft run). Once it gets over the beam it turns 90 deg and goes another 15-20 ft. The 10" round duct where the fan is mounted runs 90 deg thru the joists 10ft to the register.

I'll probably end up just getting a replacement every 2-3 years....

 

[acmikee]

what size is the HP. have you tried air balancing the system.

 

[lonestardiver]

I also have a similar issue with the master bedroom and master bath at the other end of the house. The master bedroom has 2 vents and the bath has one. Being the usual under the door return doesn’t allow for enough air return there is a through the wall vent above the door. I installed a server rack fan (48v) and run it from a laptop power supply (19-24v) so it runs about half speed. These fans are made to run 24x7x365 for years....so at half speed they tend to last quite a long time. In the summer it is great as it removes the warmer air from the room to help pull the cooler A/C air from the floor vents. (Negative pressure).

So a solution may be to use the fan to remove air from the room in order to help pull air through the duct.

 

[jade97]

I found the receipt. It's a Diversitech 625-AF6 booster can 240cfm pn 6138.

It's a 6" can adapted to the 10" duct. $32

Last replaced Feb 2019.

Someone mentioned the return vent. There is a large return in the master bedroom and none in the bath or master closet...bath is between the bedroom and closet.

 

[lonestardiver]

Can you put a fan on the return side?

 

[LS6 Tommy]

If you can access the booster fan easily then I would build a box for it where I can open a door and be able to clean or oil the bearings of the unit.

I like the brand Fantec inline duct fans. They are expensive but my 6-inch diameter dryer unit still works after 5 years of use.

X2. Duct boosters are really cheap shaded pole fans in a box. Upgrade to a Fantech. I have two of their bathroom fans. One is ~20 years old and runs perfectly.

Tommy

 

[jade97]

X2. Duct boosters are really cheap shaded pole fans in a box. Upgrade to a Fantech. I have two of their bathroom fans. One is ~20 years old and runs perfectly.

Tommy

I'll have to look into that brand. When the fan is not making all the racket, it does it's job. I will probably also get the fan properly sized to the duct.

Thank you again all for your comments.

 

[PWC Repair]

A LOT of the Diversitech stuff is ****. Fantech is great. When I worked at the supply house we had good results with Suncourt too.

 

[LS6 Tommy]

ALL of the Diversitech stuff is ****.

Fixed it for you...

Tommy

 

[jade97]

Yes, I have the same feeling about Diversitech....2 fans in 5 years.

Fantech is a bit expensive (by 10x!) and may be overkill for this one duct. When the fan is working with making the screeching or other noises, it pushes the right amount of air to properly heat the bathroom.

Lowes sells the Suncourt, but I would need to add a box & outlet (has a cord).

What is the feeling about Packard or Field Controls products?

 

[jade97]

Greetings,

I bought the 8" Suncourt and found my ducting was actually 7". Guess this is why the builder used a 6" fan. So I returned the 8" and bought a Suncourt 6". Reassembled everything and turned it on. The damn plastic can blades sound like they are hitting the housing. Now I need to pull it all apart to see if it's a fad can motor or if the housing is out of shape......��

 

[jade97]

Screws didn't go all the way through the 2 pieces of metal bending the housing in, allowing the blades to touch. All fixed and operational. This fan is very quiet. With the other brand, when new, made so much noise, we had to keep the bathroom door shut at night.

 

[allinon72]

I need to install one of these inline fans but I'm not too familiar with them - how are they typically controlled? Just run them 24/7 or activate with some type of flow switch? I want it to be 100% automated, no manual control.

 

[jade97]

I believe mine is connected through a relay in the furnace unit ( the builders HVAC guys hooked up the original,). It only turns on when the inside unit turns on.I added a switch, so I can keep it from coming on with the AC.

 

[AP514]

More likely the Builder just Split off the wiring going to the Condenser/Heater Fan.

 

[jade97]

There is Romex tapped off my water softener receptacle going to the furnace, then the furnace to the duct fan.

 

[PoorUB]

As for changing the duct size, it is not doable. Maybe I could draw out the layout at some point.

Perhaps going with rectangular duct you could increase the size and still fit.

A 10" round s good for about 420 CFM, a 10x12 rectangular is good for about 650 CFM. Even if you replaced all the duct except for a couple feet where you had to go around some obstruction it would help.