hooking stove to existing duct work in house

hooking stove to existing duct work in house

PostBy: stokerfire On: Tue Jan 04, 2011 8:18 pm

I have a keystoker 90 with a top cut for duct use .My question is where is the best place to hook to my existing duct work in house to make use of it the best way possible,would it be at the plenum or either sides of it to heat all rooms equally?My house is a one floor ranch.Any suggestions would greatly be appreciated thanks.
stokerfire
 
Stove/Furnace Make: keystoker
Stove/Furnace Model: 90

Re: hooking stove to existing duct work in house

PostBy: WNY On: Tue Jan 04, 2011 8:40 pm

I have one and tried it with just an 8" duct upstairs. In my situation, it didn't work, the stove ran full bore almost all the time and it didn't heat much upstairs especially below 20-25 degrees. The basement was pretty warm. But, that's my situation. These are stoves, not furnaces, what might work for some, may not for others.

The biggest problem I see, is the blower is only 265CFM. Most furnaces are 1500CFM. I don;t think you will have enough air flow with the stock blower to move enough air thru the ducts. Also, you are only pulling air from the back and top of the stove, you loose a lot of heat from the sides into your basement, even if you use the furnace blower, it probably won't get hot enough from the stove to overcome the airflow and just blow cooler air.

If you have it centered, you might be able to hook it into the duct work, but may need dampers, so the heat goes the right way, depending on how you are controlling the airflow and if you can control your furnace blower separately.

Good luck.
WNY
 
Hot Air Coal Stoker Stove: Keystoker 90K, Leisure Line Hyfire I
Coal Size/Type: Rice
Stove/Furnace Make: Keystoker, LL & CoalTrol
Stove/Furnace Model: 90K, Hyfire I, VF3000 Soon

Re: hooking stove to existing duct work in house

PostBy: Coalfire On: Tue Jan 04, 2011 8:42 pm

WNY wrote:I have one and tried it with just an 8" duct upstairs. In my situation, it didn't work, the stove ran full bore almost all the time and it didn't heat much upstairs especially below 20-25 degrees. The basement was pretty warm. But, that's my situation. These are stoves, not furnaces, what might work for some, may not for others.

The biggest problem I see, is the blower is only 265CFM. Most furnaces are 1500CFM. I don;t think you will have enough air flow with the stock blower to move enough air thru the ducts. Also, you are only pulling air from the back and top of the stove, you loose a lot of heat from the sides into your basement, even if you use the furnace blower, it probably won't get hot enough from the stove to overcome the airflow and just blow cooler air.

If you have it centered, you might be able to hook it into the duct work, but may need dampers, so the heat goes the right way, depending on how you are controlling the airflow and if you can control your furnace blower separately.

Good luck.


Agreed, when I had the Mag I ran one single duct from the stove. Steps were cold air return, this worked fairly well. I think if you try to tap into the duct work the heat will get lost and never come out.
Coalfire
 
Hand Fed Coal Stove: DS Machine 96K btu Circulator
Coal Size/Type: Nut


Re: hooking stove to existing duct work in house

PostBy: WNY On: Tue Jan 04, 2011 8:51 pm

Maybe try ONE duct, If you can replace one from your furnace in the center of the house and hook up your keystoker, try it and see if you can get the warm air upstairs as an experiment without cutting or ripping into your furnace. Make sure you block off the front of the stove, so all the air goes up the pipe.

Attached....
This was my original setup, my old furnace is just convection, the large pipe is the cold air return, I just ducted it up thru the big grate in the living room. It did work, just not warm enough for us when it got really cold.

I have a Hyfire with a heat jacket and it works quite well now hooked up the same way.
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WNY
 
Hot Air Coal Stoker Stove: Keystoker 90K, Leisure Line Hyfire I
Coal Size/Type: Rice
Stove/Furnace Make: Keystoker, LL & CoalTrol
Stove/Furnace Model: 90K, Hyfire I, VF3000 Soon

Re: hooking stove to existing duct work in house

PostBy: Bratkinson On: Wed Jan 05, 2011 1:39 pm

Perhaps the biggest obstacle to overcome is how to get enough air volume to blow the warm air throughout the house. This is a multiple choice question with many correct answers. It varies from situation to situation.

Like others before me, in my anxiousness to get up and running with my brand new stove 2 years ago, I found that out the hard way that 265 CFM doesn’t cut it. I had simply connected the 6” duct from the top of my Alaska Channing III (a dealer-installed option) to the hot air side of the main trunk of my gas forced air furnace and let ‘er rip. Running the stove at 3 or more (medium+ fire level) continuously, after about 24 hours, it was pleasant on first floor (that’s all I’m heating in my 60 year old cape-cod style house). The basement was very toasty, account heat loss through the ductwork, including the extra 9’ or so I added getting from my stove to the furnace duct. My magnetic thermometers also showed 400 degrees or so on the sidewalls and front of the stove radiating freely into the basement as well. So I used a 20” box fan to blow diagonally across the left side of stove to richochet off the back wall and collect the radiant heat from the right side and direct it towards my basement steps. There I had another box fan blowing the air up the steps. Since I fired up in mid February and knowing I’d only run until mid April or so, I figured I’d get by with it as is until fall. The two main failures I had was in not realizing that 265 CFM through the central heating system is woefully inadequate and that I’m wasting lots of heat into the basement. Another lesser problem was that of hot air heading backwards (toward) the furnace plenum from my connection about 4’ away from the furnace.

So, on the advice of a HVAC friend of mine, I cut a 24” x 30” hole in the “down” plenum (cold air side) of my furnace, disconnected my stove from the duct work, and turned on the furnace fan 24x7. It worked very well at distributing heat evenly throughout the house. However…I didn’t like the idea of throwing all that heat around the basement, needlessly (trying) to heat the basement walls, concrete floor, etc. Also, it jumped my electric bill by about $40 the first month. And I’m basically a cheapskate.

So, in Nov ’09, I built a heat jacket for the stove and connected it’s output to the main furnace duct in addition to reconnecting the original duct from the stove. To feed it, I discarded the 265 CFM fan that came with the stove and bought two 405 CFM centrifugal fans online. One I connected to the stove where the 265 CFM fan had been (2 weeks to engineer a custom 6” round attachment to 2x4” square connection on the stove). The other fan feeds the two side panels of the custom made jacket. Each fan draws from a ‘tap’ I made on the living room cold-air returns and I put dampers in to block off drawing cold air through the furnace (possibly sucking warm air backwards through the entire furnace). See my setup here http://nepacrossroads.com/about389-390.html About ½ way down the page.

I’ve been quite satisfied with the results. Recognizing that the 405 CFM fan rating is with no ductwork attached (“free air flow”), I’m guessing I’m getting 250+ out of each fan due to the ductwork turns, leakage, etc. But if one were to consider the original 275 CFM fan blowing at perhaps 175 CFM or so (how they managed to figure 275 CFM with a 2.3”x4.25” (roughly 12 square inches) feeding a 6” duct (3” squared x pi = 28 square inches, more or less) is beyond me), I’m far ahead of the game pushing 500+ CFM through the ductwork these days.

The two problems of my installation is the significant air flow ‘whoosh’ sound through one of my cold air return vents in the living room, mostly due to a very sharp-edged 90 degree turn just below the vent. I made some adjustments this fall and improved it somewhat. The other minor problem was the ‘back flow’ into the furnace from my connection to the hot-air side of the ductwork. I fixed that this year by the insertion of a tight-fitting sheet of metal into the ductwork between my connection and the furnace. Between that fix and some revisions to the cold-air ductwork, I’ve reduced my coal consumption by about 25% this season over last.

In summary, the three biggest obstacles to overcome are (in order):
1. Getting sufficient air flow through the hot-air system heat ducts
2. Establishing a complete “air circuit” through the stove
3. Getting as much heat as possible from the stove to the living area
Bratkinson
 
Stove/Furnace Make: Alaska
Stove/Furnace Model: Channing III

Re: hooking stove to existing duct work in house

PostBy: stokerstroker66 On: Fri Jan 07, 2011 11:26 am

Forget about theories,laws and guessing possibilities. The best advise is experience.

I own a 105 double wall Keystoker. I have it hooked up to my existing forced air furnace air duct. I am heating two floors totaling 2400 square ft. I installed a fan/limit switch from the stove's supply to the blower motor of my furnace. When the stove reaches the temperature I have set on the fan/limit switch,the furnace blower goes on. I installed a large damper inside the main trunk, slowing down the air movement.

To prevent the heated air from cooling down within the ducts:
(1) Hook up to the LOW SPEED setting of the furnace blower motor.
(2) Add a DAMPER in the main truck line.
(3) Set the fan/limit switch to a HIGH temerature.

I also hooked up a whole house humidifier that is also triggered by the fan/limit switch. My stove idles 95% of the time and maintains my set point without the furnace blower activating. My ducts stay warm to the touch with only the stoves fan (it's a very light air movement but good enough)

I also installed a thermostat with a clean cycle switch for the forced air unit. If my stove doesn't activate the furnace blower, the thermostat will (five minutes every half hour).This helps to circulate, filter, and humiditify my home.You should hook up your stove to the return side of your furnace. If you are unable to use the return side, you can use the feed side, just make sure to use a take off with a scoop. This will prevent the furnace blower from blowing the air stream into your stove.
stokerstroker66
 

Re: hooking stove to existing duct work in house

PostBy: Mike Wilson On: Sat Jan 08, 2011 9:45 am

StokerStroker, when you say a double walled 105, do you mean the entire stove has a double steel wall on it, including both sides, so that there is an air plenum on the left, right, back, and top sides? If so, wow, I didn't know they even offered that (maybe they didn't when I ordered mine a few years ago), but perhaps it could be simulated, like many have done, with sheet metal.

-- MW
Mike Wilson
 
Stove/Furnace Make: Keystoker 90 DV
Stove/Furnace Model: Jøtul Kennebec Wood Insert

Re: hooking stove to existing duct work in house

PostBy: stokerstroker66 On: Sun Jan 09, 2011 9:44 am

Mike Wilson wrote:StokerStroker, when you say a double walled 105, do you mean the entire stove has a double steel wall on it, including both sides, so that there is an air plenum on the left, right, back, and top sides? If so, wow, I didn't know they even offered that (maybe they didn't when I ordered mine a few years ago), but perhaps it could be simulated, like many have done, with sheet metal.

-- MW


You are correct. My Keystoker is double walled on both sides and the top. It's like having a built in jacket. Clearance is less, so I can set the stove closer to my walls. I believe the 105 is the only one that's offered this option.
stokerstroker66
 

Re: hooking stove to existing duct work in house

PostBy: Mike Wilson On: Sun Jan 09, 2011 10:52 am

Wow, spectacular, and exactly what I'd like to have... but the 90 is already installed and connected. Oh well.

Would you post a few photos of your stove here, I'd like to see how it looks/operates.

Thanks,

MW
Mike Wilson
 
Stove/Furnace Make: Keystoker 90 DV
Stove/Furnace Model: Jøtul Kennebec Wood Insert