Hooking up in line fans to boost temperature in one room

**simonmason** · 11-21-2012, 08:13 AM

My Comfortmaker system was installed and two in line fans were added to boost the output to one room. The fans were wired to an always on AC connection and as far as I can tell have both burned out over time. I am about to replace them and I see two options - hook them to an AC line that receives power when the furnace is running or hook them to duct stats. My preference is to do the first because it is cleaner, less things to go wrong. I cannot find any documentation on my furnace so I was wondering if anyone had any links to information that will help me figure out if there is a switched 110v coming off the furnace for running accessories? Thanks.

**Chris_Worthington** · 11-21-2012, 08:24 AM

Thread relocated to AOP

**heaterman** · 11-21-2012, 08:39 AM

Care should be taken not to exceed the amp capacity of any control boards or controls on your furnace. Doing so will cause over loads resulting in failures that will be expensive. There are several ways to achieve what you want but site rules prevent any detailed DIY instructions. Any competent local HVAC professional should be able to help you with this.

**motoguy128** · 11-21-2012, 09:25 AM

Two inline fans to boost output to a single room?

Has anything else been done to balance the system?

Duct fans should be a last resort after everythign else has been tried.

Fantech makes some good quality inline mixed flow fans. I have one in my home exhausting my garage that's going on 1-1/2 years running continously.

I would power it seperate of the furnance and use a relay triggered by the "EAC" output on the furnace board so it runs when the furnace blower runs only.

**simonmason** · 11-21-2012, 07:00 PM

Thanks for the help. The relay sounds like the way to go. I don't want the fans running all of the time as it will reduce their life and consume electricity. The room is on the outside of the house - a converted porch - with windows on three walls - so it is always cold or hot depending on the season. I am not sure why two fans were installed - I will try hooking them up one at a time.

Originally Posted by motoguy128

Two inline fans to boost output to a single room?

Has anything else been done to balance the system?

Duct fans should be a last resort after everythign else has been tried.

Fantech makes some good quality inline mixed flow fans. I have one in my home exhausting my garage that's going on 1-1/2 years running continously.

I would power it seperate of the furnance and use a relay triggered by the "EAC" output on the furnace board so it runs when the furnace blower runs only.

**Shophound** · 11-21-2012, 07:19 PM

Did the room ever stay comfortable when the booster fans worked?

**fliks** · 11-21-2012, 08:03 PM

I have used pressure or sail switches. If their is poor return with door shut an additional return would probably help.

**simonmason** · 11-21-2012, 11:14 PM

I can't remember. I don't know how long it has been since the fans have been working. The room is always cold.

Originally Posted by Shophound

Did the room ever stay comfortable when the booster fans worked?

**Hiptech** · 11-21-2012, 11:38 PM

Originally Posted by simonmason

I can't remember. I don't know how long it has been since the fans have been working. The room is always cold.

Think I would spend my time and money on insulating and draft-sealing the room. Converted porch will never be comfortable unless these issues are addressed first, especially with that amount of windows. Boost fans alone will not do the trick.
More than likely insulation is poor at best, that is where I would look first, if you want to actually make the room usable.

Hiptech

**catmanacman** · 11-22-2012, 11:07 AM

perfect solution would be a ductless mini split

**simonmason** · 11-22-2012, 11:21 AM

Thanks for all of the help. I agree that the mini split would be a good solution - albeit a lot more expensive than two duct fans! The room was done properly - insulated, etc. However, it is cold because it is on the outside wall of the house and has casement windows going from 18" above the floor to the ceiling on three walls. So there wasn't much room for insulation except around the bottom of the walls and in the ceiling. There is no return in the room - the closest return is in the next room. The room is mostly laid on a concrete slab although there is access underneath at one end of the room. Would adding a return make much of a difference?