HVAC experts - need advice on circulating some heat!

[BlueRidgeMark]

Okay, so I don't hijack mga's thread, I'll start my own.

Here's the deal: My woodstove is in the "family room" at one end of the house, and the living room (where we spend most of our time) at the other end doesn't stay warm enough. The family room/kitchen area is usually too hot, along with the kid's bedrooms.

I've installed a 10" ventilation fan in the corner of the doorway leading from the family room to the other end of the house, and that has helped quite a bit. But not enough! And it's noisy, too.

I have no central heat or AC, therefore, no existing ductwork.

So, I want to put in some ductwork and a blower to move air from the hot to the cold. I plan to have an air intake in the ceiling of the family room (where the stove is) connected to a blower motor, pumping the air through standard HVAC ducting to the living room at the other end of the house. I also want to split off a smaller line to the master bedroom. Both of these will exit into the room(s) via a standard ceiling register, and return air just goes down the hallway, back to the family room.

I can do all the work, but I don't know the design elements of HVAC, so I'm looking for advice on sizing and materials, plus places to buy online, if you have any good sites.

Preferences:

I'd like a multi-speed blower, if possible. 3 speed, or at least two. On the other hand, I already have a single speed blower on hand (squirrel cage and motor) that my Dad gave me, but don't have any specs on it right now. Got to drag it down from the attic.

I'd like intakes with built in filters, as this house for some reason is very dusty.

I'd prefer to avoid fiberglass insulation, because I'm tired of fiberglass!

However, I'll listen to the advice of those more qualified than I.


So, any HVAC guys out there?

 

[mga]

is this blower you have from a furnace?

 

[laynes69]

I wouldn't want something too powerful to push the air from one end to another. A standard furnace blower would cool the air too much. You need a gentle flow of air and the ducting well insulated to hold the heat. Another problem is the ceiling diffusers. The return up high in the stove room will work fine, Just don't place it too close to the stove. Anywhere in the room would be fine as heat rises. But those ceiling diffusers are difficult because the heat will stay on the ceiling. Running a ceiling fan on low would help circulate the heat. I could see maybe a 500 cfm blower max on a 8" line maybe a 10" with a tee for one room may work. If your running it in the attic, I would use insulated flex ducting to try it. Its cheap and you won't see high temps in it. Of course one issue is fire, but.... Just place the fan where its most likely not to be heard. I'm not a hvac pro, but designed and built my entire ducting system in my home. Theres probably code issues, but i'm sure it would help distribute the heat in the home. Build an enclosure around the blower and make a place to insert the filter.

 

[torgo111]

it would be close to impossible to move hot air from a room and get a hot air feed in other rooms. you would get a better result by moving the cold air from the cold rooms and dumping it near the stove. the hot air will move into the rooms you are pulling from. i have central air but to move the hot air near my stove i use a box fan on the floor and blow the cold air to the room i have my stove. if i run my a/c blower it just blows cool air. if you have a basement run a return duct and put floor return registers in and have a supply feed near the stove on the floor.

 

[BlueRidgeMark]

is this blower you have from a furnace?

Not a regular furnace blower - it's smaller than that. Dunno for sure what it's from. Maybe a ventilation system of some kind.

 

[Rookie1]

Wheres AOD he rigged up something on his woodburner last year. I think he didnt have a big enough blower to get the hot air to the register before it cooled off. Calling AOD. Hello Hello.

 

[BlueRidgeMark]

Another problem is the ceiling diffusers. The return up high in the stove room will work fine, Just don't place it too close to the stove. Anywhere in the room would be fine as heat rises. But those ceiling diffusers are difficult because the heat will stay on the ceiling. Running a ceiling fan on low would help circulate the heat.

Ceiling fans are already in place. I don't have any options other than running it in the attic, from ceiling to ceiling. If it comes out in the back of the room, it will get pushed down by the first of two ceiling fans as it makes its way to the front of the room, where the door is. That's the only outlet, so the warm air WILL travel the length of the room on its way back to where it came from.

I Build an enclosure around the blower and make a place to insert the filter.

That's why I want the filters built in to the intakes - so I can service them without going into the attic. Like these:

http://www.hvac-runner.com/Return-Filter-Grille-722--35.html

 

[Davej_07]

it would be close to impossible to move hot air from a room and get a hot air feed in other rooms. you would get a better result by moving the cold air from the cold rooms and dumping it near the stove. the hot air will move into the rooms you are pulling from. i have central air but to move the hot air near my stove i use a box fan on the floor and blow the cold air to the room i have my stove. if i run my a/c blower it just blows cool air. if you have a basement run a return duct and put floor return registers in and have a supply feed near the stove on the floor.

I agree with the idea of drawing off the cold air to pull heat into the room. My only concern is that the draw of air would make the room feel drafty if youre pulling 500 cfm. An 8" round duct pulling 500cfm would five you [email protected] friction loss, and would probably end up in alot of wind noise at the grilles. A 10" pipe drops the fpm to 917, so I would recommend that. IMHO stay away from flex unless youre only travelling 10' per run. 1 foot of flex has the same friction loss as 10ft' of metal pipe of the same diameter. Definatly insulate any duct youre running in the attic and you should be ok.
As far as mounting the fan, you can but isolators from Grainger to keep the noise from travelling thru the house.
BEst of luck!

Dave
16yr Union Sheetmetal Worker

 

[mtfallsmikey]

I agree with the idea of drawing off the cold air to pull heat into the room. My only concern is that the draw of air would make the room feel drafty if youre pulling 500 cfm. An 8" round duct pulling 500cfm would five you [email protected] friction loss, and would probably end up in alot of wind noise at the grilles. A 10" pipe drops the fpm to 917, so I would recommend that. IMHO stay away from flex unless youre only travelling 10' per run. 1 foot of flex has the same friction loss as 10ft' of metal pipe of the same diameter. Definatly insulate any duct youre running in the attic and you should be ok.
As far as mounting the fan, you can but isolators from Grainger to keep the noise from travelling thru the house.
BEst of luck!

Dave
16yr Union Sheetmetal Worker

Welcome Dave...nice to see some more tin knockers come to the site....

Ditto, and rep for ye!

 

[Cambium]

Before you go spending a ton of money let me tell you, circulating the air with the vents doesn't help....for me.

I got a ranch house so I got a similar problem. Wood stove in Living room but bedrooms on other end of house don't warm up fast enough. (takes 7hrs for heat to get there!)

It's a toasty 72 degrees in living room, 69 in kitchen, 65 in hallway but 62 in bedrooms.

I tried a box fan in hallway to pull the warm air...(noise, messy and it made the rooms cooler)

Then I tried turning on the central HVAC system without the heat or cooling. Just the blower.... The temp actually drops a few degrees in each room! It doesn't work. It's blowing air thats cooling the air in the room; plus since the blower is downstairs, it might be drawing cooler air from the basement!

I haven't tried ceiling fans BUT I AM CONSIDERING ANOTHER SMALL STOVE ON THE OTHER SIDE OF HOUSE SOMEWHERE.

 

[BlueRidgeMark]

B
Then I tried turning on the central HVAC system without the heat or cooling. ... since the blower is downstairs, it might be drawing cooler air from the basement!

Of course it is! You were just blowing around the coldest air in the house.


I would be pulling the hottest air in the house - right from the ceiling near the stove - and shipping it directly to the coolest spot in the house.

 

[Cambium]

Of course it is! You were just blowing around the coldest air in the house.


I would be pulling the hottest air in the house - right from the ceiling near the stove - and shipping it directly to the coolest spot in the house.

Good point...go for it. lol Unless I put a small stove in the basement. Hmm. Is it worth the $700 investment this year? (parts & stove)...

Who am I kidding...I love the winter!

 

[cre73]

I am no expert by any means but the solution I have put in place seems to work. I have an 1800sq ft ranch home with the stove at the opposite end of the home than the bedrooms. I started running a small fan on low sitting on the floor in the hallway blowing back towards the stove, which worked fine in moderate temperatures. When it got cold it wasn't quite enough. I ran a six inch flexible duct with an inline fan in a service area above the hallway(cathedral ceilings through out house except this area) this in conjunction with the fan worked perfectly in my opinion. It can actually get the bedrooms to warm in my opinion, I like to be nice and cool when I sleep.

 

[torgo111]

unless you are pulling 200* air you will not get a warm air supply after running it through a blower and insulated duct work running in a cold attic. to get very warm air you will have to pull air near the stove witch will most likely interfere with the draft.

 

[Cambium]

I ran a six inch flexible duct with an inline fan in a service area above the hallway..... I like to be nice and cool when I sleep.

Hmmmm! So cut a vent in ceiling above or near the stove, run a 6" flex duct through the attic, and cut a vent in hallway on otherside of house. Hook up a small fan in the vent near the stove and that will draw and push the warm air to the other vent in the hallway.

Can I assume you won't pull out too much warm air from living room where the living room doens't get warm as before?

 

[cre73]

I have not had any issues and it has worked well for me. The inlet is about nine feet high propably 12' away from the stove.

 

[laynes69]

Here is the thread I saw earlier. He says it works okay.

http://www.**********/econtent/index.php/forums/viewthread/40728/P22/

 

[mtfallsmikey]

What would really be cool is a low-velocity air circulation system with a VFD-driven fan, system designed from the ground up...

 

[RCR 3 EVER]

We have a fireplace in Living room at one end of ranch with bedrooms dow the one hall at other end. The kitchen/Dining room are behind the fireplace and are heated by the fireplace gravity vents that also have a blower control. The living room has a cold air return register at ceiling we increased in size to 30"l x 14"w. We also closed the floor vents to the Living room. All the registers are open to the rest of the house are open including the basement that only has 2 heat registers. I do NOT want the basement to freeze with no heat in basement! I partially blocked about 25% of the cold air return vents in each of the 3 bedrooms since I had increased the Living room register. Am I on the right track in blocking some of the return vents to force more draw from the hot living room?

It only takes about 2 hours for the furnace fan to start circulating slightly warm air to areas of the house that need it. I also installed 1 small equipment cooling box fan 239 CFM in hallway directed to bedrooms at ceiling, this pushes hot air very quick to bedrooms without cooling effect.

Problem area:
The Kitchen /Dining area are stifling 82+ degrees with the 2 gravity vents. I need to direct some of this heat downstairs to basement,which is directly across from 1 vent using 2 box fans. I thought I could put in a ceiling vent with another box fan in attic with an insulated duct routed to a bedroom, but worried about transferring kitchen smells or burnt food odors or fish smells to rest of house. Any suggestions?

The equipment cooling box fans are nice in that they are small 6" sq., quiet & extremely efficient. My fans are 239 CFM and need only .23 amps at 115 volts.

 

[BlueRidgeMark]

I am no expert by any means but the solution I have put in place seems to work. I have an 1800sq ft ranch home with the stove at the opposite end of the home than the bedrooms. I started running a small fan on low sitting on the floor in the hallway blowing back towards the stove, which worked fine in moderate temperatures. When it got cold it wasn't quite enough.

That's exactly what we did using a standard 20" box fan, though a couple of years ago I mounted a 10" ventilation fan in one of the upper corners of the doorway. It blows warm air down the hall towards the living room, and it makes a HUGE difference. But, as you found, not quite enough in the coldest weather.


Since simply putting a fan in a hallway has made such a large difference, I find it hard to believe that an insulated duct will not be effective.

I ran a six inch flexible duct with an inline fan in a service area above the hallway(cathedral ceilings through out house except this area) this in conjunction with the fan worked perfectly in my opinion. It can actually get the bedrooms to warm in my opinion, I like to be nice and cool when I sleep.

That's pretty much my plan, though I hope to eliminate the fan completely. Have to, really, as it would be working against my duct.