Another moving heated air thread....

[precaud]

Sure Freddy, some of this may be repetitive but its always good to remind ourselves of the basics.

It all revolves around the concept of "temperature differentials". This is what causes air to move - heated air rises, pushing down cooler air. It is the energy we want to take advantage of, both for heating and for transport.
It is also what creates heat loss, as materials in contact seek temperature equilibrium.
No matter how we go about it (fans, natural convection, whatever), what we're doing is moving heated air along the ceiling into rooms adjacent to the heat source. The ceiling is the transport mechanism, just like a water pipe is the transport for water.
Add to this, the hottest air is "trapped" in the room of the heat source, by the height of the doors. If door openings extended to the ceiling, the hottest air would move.

So how do we optimize this event?
Hyper-insulate the ceiling, to minimize heat loss along the transport mechanism, where loss would be the greatest. (I put R60 in my LR where the stove is, and R54 to R38 everywhere else)
Put a vent/opening in the wall at ceiling level between rooms where you want the heated air to move. (In my case, one 8"x28" opening did the trick).

That's all it takes.Your stove is making the heated air. It will move up and expand out. Colder air will then flow in along the floor from adjacent rooms to take its place. A natural convection loop, controlled by your stove.

 

[HotCoals]

To see how things are moving tack toilet paper up in doorways..hallways and where ever..maybe foot long strips.
Then hold a strip down towards the floors in the same areas...then try it with fans on if you want to.
It may surprise you.

 

[precaud]

Good idea. Or tape up 1 ft pieces of sewing thread in doorways and the output side of vents.

 

[wishlist]

Fan is installed! Should have done this 5 years ago.

I installed an 8" 720cfm inline fan ( vortex) which has a really good performance curve with higher static pressure then some of the other cheaper fans. Its installed on the cold air return supply side of my forced air furnace and the discharge is isolated and discharges near wood stove.

Its 40 outside so I don't have the stove "cranking " but a few things I have already noticed. Its 72 at the indoor/outdoor thermometer which is just to the left of the stove ( been there for years) and its 70 in the hallway on the digital thermostat. Having a ranch house its difficult to get the heat down the hallway. Never have the 2 thermometers been so close in temps.

I took some pics of the cold air return and you can see a plastic bag will stick to the vent. Also checked the vent in the bedrooms, same thing. Pic near stove is a plastic bag tied to the register and I actually had to hold down the vent with my hand or the vent will come out. I also held a small piece of plastic bag in the header above the hallway entrance and you can see the bag being pulled down the hallway towards the bedrooms. This is most important as I can verify heat will be traveling down the hall.

I'm going to install a speed controller next and do some more testing, need a real cold day but I'm positive this works very good.

 

[Todd 2]

Wishlist, sounds like you might have a winner there guy, the speed control should be the cats meow as they say.
You'll learn the best flow for the outdoor temps and stove btu's. Add a stat an you'll have almost hands free operation. One thing I did forget to mention earlier in this thread to you was to consider installing the fan so you could have easy access to clean it. The blades will get dirty in time and slow the flow.
Huntin weather has been crappy here, unless your a duck. Todd2

 

[wishlist]

Wishlist, sounds like you might have a winner there guy, the speed control should be the cats meow as they say.
You'll learn the best flow for the outdoor temps and stove btu's. Add a stat an you'll have almost hands free operation. One thing I did forget to mention earlier in this thread to you was to consider installing the fan so you could have easy access to clean it. The blades will get dirty in time and slow the flow.
Huntin weather has been crappy here, unless your a duck. Todd2

I have easy access to the fan Todd. I have an unused switch in a gang box that i have access to (didn't need 3-way for remote control ceiling fan) that is in the wood stove room so no need going downstairs to control speed of fan. After the speed control I will install the stat. I think a line voltage stat ( heat pump, baseboard heater? ) is what I'm looking for? I could install a probe in duct but I think a room temp stat will work better.

Duck or goose hear as well. Wind calmed down so I'll be in the tree tomorrow morning. Good luck to you.

 

[Huntindog1]

If your looking to learn about how to move heat thru you house there are some terms you can search on Google that brings up alot of info.

Stack Ventilation
Cross Stack Ventilation
Natural Ventilation

I was looking up info for my new divider wall in my basement. As it has changed my air flows in my house as to getting heat upstairs.
There is a term for vents in a single wall, single-sided natural ventilation.

 

[freddypd]

Fan is installed! Should have done this 5 years ago.

I installed an 8" 720cfm inline fan ( vortex) which has a really good performance curve with higher static pressure then some of the other cheaper fans. Its installed on the cold air return supply side of my forced air furnace and the discharge is isolated and discharges near wood stove.

Its 40 outside so I don't have the stove "cranking " but a few things I have already noticed. Its 72 at the indoor/outdoor thermometer which is just to the left of the stove ( been there for years) and its 70 in the hallway on the digital thermostat. Having a ranch house its difficult to get the heat down the hallway. Never have the 2 thermometers been so close in temps.

I took some pics of the cold air return and you can see a plastic bag will stick to the vent. Also checked the vent in the bedrooms, same thing. Pic near stove is a plastic bag tied to the register and I actually had to hold down the vent with my hand or the vent will come out. I also held a small piece of plastic bag in the header above the hallway entrance and you can see the bag being pulled down the hallway towards the bedrooms. This is most important as I can verify heat will be traveling down the hall.

I'm going to install a speed controller next and do some more testing, need a real cold day but I'm positive this works very good.

This is great stuff, but would you mind explaining a little further? I also have a ranch house and am having trouble getting heat to the bedrooms.

Are you sucking cold air from the bedrooms and discharging it in stove room?

Could you put a link to the items you purchased?

I have hot water baseboards and central AC. I am guessing I would have to run a new independent system of vents?

Thanks.

 

[wishlist]

This is great stuff, but would you mind explaining a little further? I also have a ranch house and am having trouble getting heat to the bedrooms.

Are you sucking cold air from the bedrooms and discharging it in stove room?


Could you put a link to the items you purchased?

I have hot water baseboards and central AC. I am guessing I would have to run a new independent system of vents?

Thanks.

Freddy, yes I am sucking cold air from the back bedrooms and hallway and blowing it to a vent close to my wood stove. Same principal as many do with box fans at floor level and blow towards stove.

I have installed a fan speed control to turn the fan down some, works great. You have to make sure the speed control is rated at least for the amp draw of the fan. HD and Lowes only sell regular ceiling fan speed controls rated for 1.5 amp. My fan is rated at 2.2 amps so I went to a local electrical supply house and picked one up for $21.

I think I could have used a 6" fan instead of the 8" but the 8" wasn't much more $ and I didn't want to redo the system. I'm using the smartphone and unable to post a links ( phone is smarty then me) but my fan is made by Atmosphere.com. They have a website with info. Cheapest place I found was plantlightinghydroponics.com its $179 for the 8" vortex.
Hope this helps, Bob

 

[westkywood]

Before I knew to push cold air instead of warm air, I put ducts in my attic to blow hot air from the wood stove room back to 2 bedrooms. I have a vent just above the wood stove. There is a 10 inch fan in the duct above the stove with 10 inch duct that eventually Y's off into two 6" ducts that goes to 2 bedrooms. I have a reverse thermostat by the stove that turns the fans off when the stove cools down so its not blowing cold air when the stove cools off in the morning. It blows good hot air, but I understand the error of my ways now. Can I just turn the fans around so the air blows into the stove room? My problem is the vents are all in the ceiling and not on the floor so I wouldn't be blowing the coolest air from the bedrooms. It would be blowing the warmer air from the bedrooms.... Thanks. ( great thread )

 

[wishlist]

West, if your fan is an inline fan you can turn it around and see if that makes a difference in your situation. Never know unless you try.

 

[westkywood]

West, if your fan is an inline fan you can turn it around and see if that makes a difference in your situation. Never know unless you try.

Yes they are inline, but gonna be a PIA to get up in the attic, cut open the duct work and reverse them.. My thought on it is, if I reverse them, it will only work properly if I leave the bedroom doors open. Correct?

 

[wishlist]

Yes they are inline, but gonna be a PIA to get up in the attic, cut open the duct work and reverse them.. My thought on it is, if I reverse them, it will only work properly if I leave the bedroom doors open. Correct?

Since your creating a negative draft in the bedrooms, I would think it would draw air from the easiest place, under the door if you have an opening. If the door is rather flush to carpet etc.... then I would guess it them would draw through leaks in windows. Btw, are you using the "booster fan" or a high cfm inline fan? The booster fans are around $40 and the inline centrifugal fans are over $100 or so. With my setup I'm moving a substantial amount of air which really helps in assisting the natural circulation in my opinion.

 

[freddypd]

Wishlist, you should put this thread in your signature. I am sure many people would be interested in this over the years.

Thanks.

 

[westkywood]

Since your creating a negative draft in the bedrooms, I would think it would draw air from the easiest place, under the door if you have an opening. If the door is rather flush to carpet etc.... then I would guess it them would draw through leaks in windows. Btw, are you using the "booster fan" or a high cfm inline fan? The booster fans are around $40 and the inline centrifugal fans are over $100 or so. With my setup I'm moving a substantial amount of air which really helps in assisting the natural circulation in my opinion.

They are the booster fans. I'm thinking the 6" ones are around 150cfm. There is some room under the doors for air flow. My main concern is that the vents are in the ceiling, which is going to take the heat out of the room rather than the cooler air.

 

[wishlist]

They are the booster fans. I'm thinking the 6" ones are around 150cfm. There is some room under the doors for air flow. My main concern is that the vents are in the ceiling, which is going to take the heat out of the room rather than the cooler air.

It would pull the warmer air but remember that air in the bedrooms will be replaced with air from somewhere. With the booster fans your not moving much air depending on the length of the run and if your using flex duct or solid. If I was gonna climb in the attack and change things I would replace the booster fans with an inline fan west. Maybe you can add a "Y" and use one fan? I'm amazed at how well the fan works in my house and I don't have box fans trying to move air down a hallway and then make a 90 degree turn and blow the cool air towards the stove. Definitely a huge improvement for me. Good luck in whatever you decide.

 

[westkywood]

It would pull the warmer air but remember that air in the bedrooms will be replaced with air from somewhere. With the booster fans your not moving much air depending on the length of the run and if your using flex duct or solid. If I was gonna climb in the attack and change things I would replace the booster fans with an inline fan west. Maybe you can add a "Y" and use one fan? I'm amazed at how well the fan works in my house and I don't have box fans trying to move air down a hallway and then make a 90 degree turn and blow the cool air towards the stove. Definitely a huge improvement for me. Good luck in whatever you decide.

I appreciate your input. I do have a "Y". Above the stove is a 10" fan. The duct goes about 20 feet to a "Y", where it splits to the two 6" lines. The 6" fans are at the end of those. It actually pulls pretty good. It is flex duct.