Ductwork advice

Ductwork advice

PostBy: szembek On: Thu Sep 13, 2007 11:39 am

I just installed my Keystoker A120. I have existing ductwork tied into my oil furnace. The house is a ranch and the stove is in the basement. There is a main rectangular duct that runs most of the length of the house, and several round ducts shooting off of this to each room in the house. Attached is a crude mspaint sketch of how it looks. I plan on putting a plenum on top of the A120 and running tying a duct from that plenum into the main house ducting. Is there an advantage to running it into the plenum on top of the oil furnace since this is in the center of the house? Or will it make a big deal if I just tie it into the ductwork right next to the coal stove.

Also when I have the plenum built how do you decide how tall to make it? I just plan on running 8" flexible insulated duct out of the side of the plenum to the main ductwork. Thanks for any advice you might have.
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Stove/Furnace Make: Keystoker
Stove/Furnace Model: A120

PostBy: e.alleg On: Thu Sep 13, 2007 9:54 pm

I'm not an expert but I did a ton of research on forced air heating recently and you must install a cold air return. Trying to heat either outside air or cold basement air is going to waste fuel and with no return air circulation you are going to be colder than necessary. I would duct the keystoker into the existing plenum with as large a duct as possible, an 8x16 duct should be the minimum. Cut a hole in the floor on each end of the house and run the return air into the bottom of the stove, a 8" flexible duct for each return vent should do the trick, or box in a floor joist with some tin and use that preexisting ductwork to your advantage. If you keep the basement door open all the time that might help too but I'm not sure how much.
Stove/Furnace Make: EFM
Stove/Furnace Model: 520

PostBy: szembek On: Fri Sep 14, 2007 9:30 am

Yeah for now I'm going to leave the basement door open. I've heard that works fine. Probably by next winter I'll run ductwork to the existing cold air return for the oil furnace. I see how it could be more efficient that way.
Stove/Furnace Make: Keystoker
Stove/Furnace Model: A120

PostBy: LsFarm On: Fri Sep 14, 2007 11:19 am

The problem with just using the basement door and stairway for a cold air return, is that the returning air gets quite cold when traveling over the basement floor. The furnace has to raise 40-50* air to a functional heated temp instead of regular return duct air which would be around70*. This sounds minor, but it is major.

And the return air is not a guarantee, the house will provide infiltrating air from around windows, doors, and foundation gaps. This will further increase the heat load on the furnace.

If you can I'd hook into the existing cold air return as well as the heated ductwork, connect both to the coal furnace.

Greg L
Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

PostBy: szembek On: Fri Sep 14, 2007 11:32 am

Can I run flexible insulated duct into the cold air return? That's really the only reasonable way I think I can do it. given my current layout. I'll have to think about it though, there might be other options.
Stove/Furnace Make: Keystoker
Stove/Furnace Model: A120

PostBy: coaledsweat On: Fri Sep 14, 2007 1:11 pm

szembek wrote:Can I run flexible insulated duct into the cold air return?

Yes, but save yourself the money. There is no reason to insulate the returns.
Stoker Coal Boiler: Axeman Anderson 260M
Coal Size/Type: Pea

PostBy: Jerry & Karen On: Fri Sep 14, 2007 6:16 pm

Hi Scembek, If you go to my web site there is a drawing on the hot air jacket and how to install it into existing duct work. It doesn't matter if it's a keystoker or leisure line, the ducting is all the same.
Jerry & Karen

PostBy: szembek On: Tue Sep 25, 2007 2:38 pm

Ok, the cold air return might be an addition for next winter, I think I'll do fine heating it as is this winter. I have a bathroom to finish and a baby due in 9 weeks! I ran flexible duct from coal plenum to oil plenum. I have to somehow seal the plenum on the coal stove so air doesn't blow out there. Right now I can feel air coming out of the register at the other end of the house, so it'll probably do pretty good. I'd like to get a little more force behind it though, as I think I'm losing a good amount of air pressure at the joint.
Stove/Furnace Make: Keystoker
Stove/Furnace Model: A120

PostBy: coal_kid On: Tue Sep 25, 2007 9:48 pm

That flex duct won't take the heat right off the plenium. Your going to have tempatures of over 200 degrees hitting that flex duct...

I did a quick google search for :

http://www.google.com/search?hl=en&sa=X ... 27&spell=1


Operating Temperature Range:

-20 Degrees Fahrenheit to 140 degrees Continuous
-20 Degrees Fahrenheit to 250 degrees Intermittent

You might end up with a melted mess, plastic smoke all though your house, or even worse a fire. Its not worth it. Get some big fat 8, 10 or 12 metal duct at lowes and screw it together. The duct, screws, tin snips might only be $50-$75. You don't need a cold air return to have a hot house, I'm proof of that. You can add that later.

Take a look at some of my posts
Mar 8 shows my setup good :

12/18/06 shows me getting started..
http://nepacrossroads.com/viewtopic.php ... c&start=15

The bathroom can wait, it will only cost you alot of money. The coal furnace will save you money and can be done in the middle of the winter. When your forced to stay inside.

Good luck with the baby. I have two little ones myself. When they are first born they sleep alot, take advantage while you can.

PostBy: szembek On: Wed Sep 26, 2007 9:59 am

Very interesting. The store that sold me the unit has flexible duct running out of the plenum in the store, which is why I decided to go this route. I see what your saying though. It probably won't melt, but if it did it would be very bad. I can't really run rigid pipe between them very easily because of the way everything else is set up. There is flexible aluminum duct that may do the trick though.
Stove/Furnace Make: Keystoker
Stove/Furnace Model: A120