Circulation Fan System Advice/Specifics

[PolrBear]

As we move toward autumn, I want to work on getting better warm air circulation to the far corners of the house so we don't have to waste so much electricity on space heaters in the bedrooms at night. Setup is a 1500 square foot slab on grade dwelling with attic access and our stove in the middle of the large main room. My scheme is to put a circulation fan in the attic with ducted intakes to the ceilings of the bedrooms, and an outflow in the ceiling near the stove. This gets air flowing back from the bedrooms, with the idea of creating a void that will pull in warm air and even out the temperature through the house. Fan to be controlled by a switch or possibly a thermostat. I have a vague idea how to install all this, but I'm not sure how to source an optimal fan and duct manifold (where the intakes meet), or really what to look for when I shop. Any feedback and/or specific recommendations would be awesome. Thanks!

 

[begreen]

The system will need to be very well insulated to reduce ducted heat loss.

 

[EatenByLimestone]

You’d have to air seal the penetration really well too.

I have a really small fan that I put in the upper corner of doorways and then run a larger fan on the floor. I feel the small fan blowing into the far rooms helps to establish the thermal loop. The large fan blows the colder air back toward the stove room.

Pic off Google. After 20 years my fan isn’t nearly that pretty.

 

[PolrBear]

Why is air sealing so crucial when the system is pulling air back from the corners toward the stove? Is it because the air will be coming off the ceiling and so some warm air will get cooled down in transit?

 

[Whitenuckler]

As we move toward autumn, I want to work on getting better warm air circulation to the far corners of the house so we don't have to waste so much electricity on space heaters in the bedrooms at night. Setup is a 1500 square foot slab on grade dwelling with attic access and our stove in the middle of the large main room. My scheme is to put a circulation fan in the attic with ducted intakes to the ceilings of the bedrooms, and an outflow in the ceiling near the stove. This gets air flowing back from the bedrooms, with the idea of creating a void that will pull in warm air and even out the temperature through the house. Fan to be controlled by a switch or possibly a thermostat. I have a vague idea how to install all this, but I'm not sure how to source an optimal fan and duct manifold (where the intakes meet), or really what to look for when I shop. Any feedback and/or specific recommendations would be awesome. Thanks!

To do it right you would need the same ducting as a forced air heating/cooling system. Otherwise ceiling fans and Pedestal Fans. Another option may be based on a heat recovery system with insulated ducts in your attic.

 

[Eman85]

Have you tried something as simple as a ceiling fan? We have a ceiling fan in the main room with the stove. If we forget to turn it on you know right away when you're sitting in the den which is the furthest room. flip the fan on and the heat evens out through the house, single story home.

 

[EatenByLimestone]

Why is air sealing so crucial when the system is pulling air back from the corners toward the stove? Is it because the air will be coming off the ceiling and so some warm air will get cooled down in transit?

Because you’re cutting a hole in your ceiling. Air will be escaping from around the installed ductwork. The air leaking from around your ductwork can easily turn a less than ideal solution into a net negative as the combination of little losses add up.

 

[begreen]

You’d have to air seal the penetration really well too.

I have a really small fan that I put in the upper corner of doorways and then run a larger fan on the floor. I feel the small fan blowing into the far rooms helps to establish the thermal loop. The large fan blows the colder air back toward the stove room.

Pic off Google. After 20 years my fan isn’t nearly that pretty.

I had one of those fans. It drove us nuts with the noise. A basic 5", 120v muffin fan is much quieter, though not as finished looking.

 

[PolrBear]

We have ceiling fans in all the rooms, and they do help some. They're particularly important in the main area, which has a 14' vaulted ceiling. However the bedrooms still get very chilly on winter nights. What about something like this, installed near floor level to push cold air out of the bedrooms and into the main area? https://www.amazon.com/Reversible-T...g-Temperature/dp/B0GD58S197/ref=sr_1_7?sr=8-7

 

[EatenByLimestone]

I had one of those fans. It drove us nuts with the noise. A basic 5", 120v muffin fan is much quieter, though not as finished looking.

Yeah, it’s loud. No doubt about that! By now I can ignore it though! I’m not sure it’s much louder or quieter than my squirrel cage blower on the stove when it’s on high.

 

[Whitenuckler]

We have ceiling fans in all the rooms, and they do help some. They're particularly important in the main area, which has a 14' vaulted ceiling. However the bedrooms still get very chilly on winter nights. What about something like this, installed near floor level to push cold air out of the bedrooms and into the main area? https://www.amazon.com/Reversible-T...g-Temperature/dp/B0GD58S197/ref=sr_1_7?sr=8-7

If you have electric convect heaters in those rooms I'd use them to top up the heat.

 

[OffGridICF]

You can get a duct fan from Vevor (or a more expensive AC Infinity version from Amazon). I use a 4" Vevor fan with variable speed to maintain an even temperature across multiple battery packs. The fan blows into a 3D printed plenum and out to 4 smaller flex ducts. It's been running 24-7 for a couple of years now. The ones with EC motors are more energy efficient (25W vs. 31W for the AC motor on a 4" fan). This one has variable speed, thermostatic control and a remote temperature sensor:

https://www.vevor.com/inline-duct-f...-kit-ec-variable-speed-control-p_010532060135

You could build a pair of insulated plenum boxes in the attic. One with a return air grill (or normal duct register) in the ceiling above the wood stove, the second feeding insulated flex duct to each room. Put the fan between the two boxes or maybe make one box with three chambers so the entire thing including the fan is insulated. Get standard HVAC duct boots and registers from a big box store for each room.

Amazon also has some fans that fit in HVAC registers with programmable thermostats. Search for 'duct fans'.

 

[Whitenuckler]

You can get a duct fan from Vevor (or a more expensive AC Infinity version from Amazon). I use a 4" Vevor fan with variable speed to maintain an even temperature across multiple battery packs. The fan blows into a 3D printed plenum and out to 4 smaller flex ducts. It's been running 24-7 for a couple of years now. The ones with EC motors are more energy efficient (25W vs. 31W for the AC motor on a 4" fan). This one has variable speed, thermostatic control and a remote temperature sensor:

https://www.vevor.com/inline-duct-f...-kit-ec-variable-speed-control-p_010532060135

You could build a pair of insulated plenum boxes in the attic. One with a return air grill (or normal duct register) in the ceiling above the wood stove, the second feeding insulated flex duct to each room. Put the fan between the two boxes or maybe make one box with three chambers so the entire thing including the fan is insulated. Get standard HVAC duct boots and registers from a big box store for each room.

Amazon also has some fans that fit in HVAC registers with programmable thermostats. Search for 'duct fans'.

10-11 Inch 130w Motor 12 Volt Performance Electric Radiator Cooling Fa

Electric Fan: Universal 12 volt high performance 10 inch slim electric cooling fan. Upgraded 130 watt motor draws 13 amps, producing over 2260 CFM. Configured as an air puller by default or reversible to an air pusher. Includes mounting bracket feet and complete cooler fin tie strap kit...

www.americanvolt.com

These rad fans work good according to a utube I posted on making a blast freezer. You can run it with a variable DC supply and reduce the speed a bit to find the sweet spot. I use the AC Infinity 4" as a duct blower from a register on my main floor to blow in back of my pellet stove in the basement. They work good.

 

[Murray01]

We have ceiling fans in all the rooms, and they do help some. They're particularly important in the main area, which has a 14' vaulted ceiling. However the bedrooms still get very chilly on winter nights. What about something like this, installed near floor level to push cold air out of the bedrooms and into the main area? https://www.amazon.com/Reversible-T...g-Temperature/dp/B0GD58S197/ref=sr_1_7?sr=8-7

We have a fan similar to the one you linked. My FIL installed it about 6’ off the floor with the intent of pulling warm air out of the stove room and sending it down the hallway towards the bedrooms. It certainly helps to move warm air down the hallway, one draw back is when you walk down the hallway in the middle of the night the floor is cold and a layer of cold air I can feel from my knees down.

On the low to medium setting it’s not too loud. My wife eventually solved the issue by putting electric blankets on the back bedroom's beds. The bedrooms are used rarely, company and when my snoring chases her from the master bedroom. A good warm pair of slippers also help with personal comfort.

When the temperature drops to -20C or colder we turn the baseboard heater on in the hallway and the bathroom, the wood stove only produces so much heat. Nobody likes a cold toilet seat!

 

[stoveliker]

You have a good wife (here it's me that's chased away when I snore).

I use this inline fan. I can't hear it at all. I only hear the air flow. But that's being mounted on the slab (concrete) and with a two feet of flex duct between fan and sheet metal duct. I only hear the air flow, not the fan.

TerraBloom 6" Silent Inline Duct Fan, 26W, 188 CFM, Quiet Mixed-Flow Energy Efficient Blower for Air Circulation in Ducting, Vents, Grow Tents

https://a.co/d/0dlANJre

I suggest that mounting method matters much for these things for silence. Mounting it on joists creates a good noise connection to the ceiling.

My ducts are all inside the insulated envelope though. If you're moving air thru uninsulated space, sealing is important but insulation of the duct too.
If you have R50 in the attic insulating your ceilings and add an R5 duct in the uninsulated space your losses will be relatively large even if you seal well.

 

[begreen]

The pot growing industry really helped bring some good, low-power, and quiet inline fans to the market. That looks like a nice one. Common flex ducting has R=4.2 insulation. Go for the R 8.0 stuff.

 

[PolrBear]

If you have electric convect heaters in those rooms I'd use them to top up the heat.

We have oil filled radiant heaters in the bedrooms, and they use an incredible amount of electricity to keep the bedrooms livable on cold winter nights. That's what I'm trying to fix.

 

[Whitenuckler]

Why is air sealing so crucial when the system is pulling air back from the corners toward the stove? Is it because the air will be coming off the ceiling and so some warm air will get cooled down in transit?

You should also check to see if you are allowed to cut holes in the ceiling and add ducts.

 

[Whitenuckler]

We have oil filled radiant heaters in the bedrooms, and they use an incredible amount of electricity to keep the bedrooms livable on cold winter nights. That's what I'm trying to fix.

How is the home heated? Do you just have a wood stove and portable heaters? That would not meet building code I'm sure, as for insurance you need to heat your house when you are not there. Do you have heat pumps? If you bring air back from the bedrooms through the attic (which is -30C in winter) you are going to be blowing very cold air.

 

[PolrBear]

You should also check to see if you are allowed to cut holes in the ceiling and add ducts.

We own our home and there is no county inspector or code enforcement apart from well and septic. We want to do everything properly, but it's voluntary.

How is the home heated? Do you just have a wood stove and portable heaters? That would not meet building code I'm sure, as for insurance you need to heat your house when you are not there. Do you have heat pumps? If you bring air back from the bedrooms through the attic (which is -30C in winter) you are going to be blowing very cold air.

We have a propane furnace, which serves as our main heat source during weather that's too warm for the stove, and in stove season also kicks on toward morning between the time the fire dies down and the time I get up. (I'm not hardcore enough to stoke it in the middle of the night, unless of course I happen to be awake anyway.)

Currently I'm leaning toward strategically placing a couple of through-wall fans down near floor level, pushing cold air out of the bedrooms and into the main area with the stove. I might try this to start by just putting the fans on the floor in the doorways and seeing what that does to the bedroom temperature.

The biggest problem room is our master bath, which is on the far side of the bedroom and gets cold as a tomb during the winter, even in daytime with the stove running full bore and the main area hot enough to make everyone sweat. Last winter we did a little hack where we ran the exhaust fan in this bathroom. Obviously inefficient to blow air out of your house and suck more cold air in, but it helped a lot in warming up the bathroom and also the bedroom in between. There's a bathroom at the opposite end of the house as well, and when we ran the bath fan in there, that end of the house got warmer and the main area right around the stove wasn't quite so broiling hot.

 

[stoveliker]

Creating a circuit , I.e. provide pathways for warm and cold air to flow, is the trick to get heat farther away.

Code matters for your home insurance too. And your safety.
For wall and ceilings that are fire barriers (as a wooden floor on wood joists is), it's best to add a fire damper to the duct. They close automatically (spring loaded) if they get hot, preventing smoke, (toxic) gases, and fire from having a spreading highway.

 

[Whitenuckler]

We have a propane furnace, which serves as our main heat source during weather

How does the propane furnace work? Does it have a proper air handler blower with warm and cold ducts for each room? If you are on slab I think they usually have radiate floor heating with a hot water circulation system. If you don't have heat pumps you can get multihead ones up to 3 heads. They are great above about -15C. They are very very efficient like 400%.

 

[PolrBear]

How does the propane furnace work? Does it have a proper air handler blower with warm and cold ducts for each room? If you are on slab I think they usually have radiate floor heating with a hot water circulation system. If you don't have heat pumps you can get multihead ones up to 3 heads. They are great above about -15C. They are very very efficient like 400%.

I don't know my HVAC terminology all that well, but it's an A/C + propane furnace system, both operating via forced air through ceiling ducts. I would love to have hot water based radiant heat, but apparently the builder saw otherwise. During really cold weather, this system burns a ridiculous amount of propane (sometimes running nonstop for 24 hours or more) and we never really feel warm. The wood stove has been a tremendous improvement in that regard. We're very happy with it except for the uneven heat distribution, particularly at night.

 

[Whitenuckler]

I don't know my HVAC terminology all that well, but it's an A/C + propane furnace system, both operating via forced air through ceiling ducts. I would love to have hot water based radiant heat, but apparently the builder saw otherwise. During really cold weather, this system burns a ridiculous amount of propane (sometimes running nonstop for 24 hours or more) and we never really feel warm. The wood stove has been a tremendous improvement in that regard. We're very happy with it except for the uneven heat distribution, particularly at night.

Have you tried running it in blower mode only with the woodstove? You should be able to use it to circulate the air in your house.

 

[PolrBear]

Have you tried running it in blower mode only with the woodstove? You should be able to use it to circulate the air in your house.

I have tried that and it does not seem to help at all. Might be due to the intake being quite far from the stove, albeit in the same general area.