Is there a way to lower the air temp of a duct from a wood stove


  #1  
Old 11-22-14, 10:23 PM
R
Member
Thread Starter
Join Date: Oct 2014
Posts: 22
Received 0 Votes on 0 Posts
Is there a way to lower the air temp of a duct from a wood stove

Seems like a funny title, here is what I was thinking.. This is just a little side project that I am continually working on. I have a wood furnace with a couple of its own ducts that is separate from my other ductwork. I never need to run the wood furnace and other furnace at the same time.
It is okay like this but I would like to duct just alittle bit of the air from the wood furnace into a couple of my ducts that go upstairs just to circulate some more air around. The hot air from the wood furnace I feel can get too hot to send into the duct that goes up through my wall. If I take one of the 6" branches from the wood furnace, is there something I can make to introduce some room temp air in to mix with the heated air before sending it into the duct going up the wall? I was trying to think if there was a way that the room air could be pulled into the air stream in the duct, similar to how a chimney pulls air into a barometric damper. I can't think of any way it could work.
 
  #2  
Old 11-23-14, 01:25 AM
GregH's Avatar
Super Moderator
Join Date: Jan 2001
Location: Manitoba
Posts: 10,193
Received 52 Votes on 48 Posts
When you say wood furnace I would assume you mean air tight heater or fireplace.
The fact that you can not control the combustion well enough to make this type of wood stove safe is why they are not approved for what you want to do.

Folks here could make suggestions on a make-shift way of doing this but the fact is that if you do make modifications to the heat from this unit to be circulated, your home insurance will not be valid if you were to have a fire.

You would do well to abandon this project and while you were at it make sure that the wood burner is listed and documented on your current insurance policy.
 
  #3  
Old 11-23-14, 06:00 AM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,964
Received 6 Votes on 6 Posts
I have a wood burning plenum heater in my basement that is tied to my ductwork in the house. The heater is fan forced, so when the temperature reaches a certain level it more or less takes over the job of heating and the heat pump falls off. Not sure if this is what you have or not.
 
  #4  
Old 11-23-14, 06:33 AM
R
Member
Thread Starter
Join Date: Oct 2014
Posts: 22
Received 0 Votes on 0 Posts
It is a forced air wood furnace that is about 4 years old. It does not have anything to do with controlling combustion well enough, the information from the furnace lists clearance measurements between the ducts and combustables, these clearances decrease as the distance from the furnace increase. My insurance is okay, they just want to know if you have a wood furnace or not. I know you guys think I might burn the place down, so I'm probably on my own on this, I thought I could discuss some different ideas here on a diy site but it always turns into a legal discussion
 
  #5  
Old 11-23-14, 06:39 AM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,964
Received 6 Votes on 6 Posts
Can you post a picture of the unit? It may help to know what it looks like to determine if what you are proposing is worthwhile or not. http://www.doityourself.com/forum/el...your-post.html
 
  #6  
Old 11-23-14, 06:56 AM
P
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 25,055
Received 857 Votes on 790 Posts
One way to cool the air down is to increase the air flow. It worked when I had a wood stove though it might seem counter intuitive. In my case the air just flowed between the double walls of the stove. The longer the air stayed in there the hotter it got so the faster I ran the fan the cooler the outlet temperature would get. If the furnace is really blazing you might not want or be able to flow the amount of air needed to cool it though.

Another option might be to blend the air like a car does. In a car hot water is always circulating through the heater core so it's always hot. The car makes warm air by blending together cool and hot to provide the desired temp. You might be able to do something simple like install a variable speed blower in the hot side plenum and you inject cool air to get the outlet temperature you want.
 
  #7  
Old 11-23-14, 07:03 AM
R
Member
Thread Starter
Join Date: Oct 2014
Posts: 22
Received 0 Votes on 0 Posts
Here it is, not finished yet, I still need to make a cold air return and some other changes I have a nice direct drive blower for the cold air side that I will set up with a filter and duct to replace the cheap little dual blowers the unit comes with. I was just looking to tie into the duct in the last picture going up the wall, but I wanted to take some heat off of the duct first so it wasnt too hot.
 
Attached Images    
  #8  
Old 11-23-14, 07:23 AM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,964
Received 6 Votes on 6 Posts
Except for brand name, it is almost exactly what I have. I do have a sheet metal plenum sitting atop the unit measuring about 3' tall, fastened all around with a sheet metal flange, totally enclosed. From that, I take off with an 8" duct into my existing ductwork. I am not sure if you can localize it to your upper levels, but it provides adequate heat for our house on the main floor. I'd take this opportunity to wrap all my supply lines in insulation. That alone will keep temperatures stable until they are expelled into the rooms.
 
  #9  
Old 11-23-14, 07:41 AM
R
Member
Thread Starter
Join Date: Oct 2014
Posts: 22
Received 0 Votes on 0 Posts
Okay that is good to know, thanks. Are you talking about insulating all the other ducts comming off of the oil furnace / heat pump coil ?

Here is the new blower I have, this single blower should match pretty close the cfm of the stock blowers. I am going to mount it on the wall in an enclosure with a filter intake, and the outlet will go into the back of the furnace where the original fans were mounted. It should cut down on vibrations the fans cause on the furnace sheet metal and make everything a little more quiet.
 
Attached Images  
  #10  
Old 11-23-14, 07:55 AM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,964
Received 6 Votes on 6 Posts
Yes, insulate all the supply ducts. Here is a picture of my set up. I just let the 2 ea 8" holes dump into the plenum.

Name:  plenum heater.jpg
Views: 5320
Size:  34.1 KB
 
  #11  
Old 11-23-14, 08:07 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 61,837
Received 1,475 Votes on 1,363 Posts
Interesting setup. Where's the flue Larry ?
 
  #12  
Old 11-23-14, 08:34 AM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,964
Received 6 Votes on 6 Posts
No flue. It is completely catalytic. No, just kidding. Flue exits just like ronjohnson's directly behind in a chimney thimble. You can see a slight outline of the black pipe behind the plenum. Up and over.
 
  #13  
Old 11-23-14, 09:46 AM
R
Member
Thread Starter
Join Date: Oct 2014
Posts: 22
Received 0 Votes on 0 Posts
Yep it does look like you have a similar setup. I'll look into the duct insulation, but I have to get some other things done first. thanks
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description: