Wood Furnace and downflow heating system?

[actionjack]

Hello,

I'm new here and have been researching the add on wood furnaces. I've noticed all install diagrams and pictures are all adding these furnaces to an upward flow system. My house currently has a downflow system (with crawlspace, no basement). My question is can I make this work? My house is laid out perfectly to put the add on furnace in the garage, and I can go into the crawlspace about 5' and tie in to the ductwork right below my furnace. I'm just not sure how well the heat would flow and what should be used to pipe it down there? Anyone done this before one here?

 

[brenndatomu]

Welcome to Hearth jack! Well, if you were gonna do this, know that you would have to have the blower running at all times (when burning) since you would get no gravity heating. you would also have to install a emergency heat dump for power loss etc. like this one http://store.yukon-eagle.com/safety-heat-dump/
Also, no mfgr. that I know of would endorse this, which means your HO ins won't either

 

[actionjack]

Thanks for your reply. Interesting, so it's doable but not the "best" idea. Is there anyone on here that has done this?

Also, can't this be wired to a thermostat and used just like a furnace? My thought was having two thermostats (IE: have the wood burner set at 75 and furnace set at 65 in case I work late and can't make it home to keep fire going. Anyone do this?

 

[brenndatomu]

My thought was having two thermostats (IE: have the wood burner set at 75 and furnace set at 65 in case I work late and can't make it home to keep fire going

Yup, that's pretty common. My Yukon wood/oil combo furnace uses 2 stats from the factory, it has a circuit board that locks out the wood damper if the oil burner kicks on (but that never happens at my house )

 

[actionjack]

So how could I wire mine to where it shuts off the blower on the woodburner when the furnace kicks on (meaning the fire has dwindled)? Or would the blower shut down automatically on the wood furnace once it cools to a certain temp? I'm looking at a US Stove or a Deka by the way....

Sorry if these are simple questions, I've got friends that have these to help me install but I'd still like to have a good understanding

 

[brenndatomu]

The limit switch will kick the blower off when temps cool.
You have friends that have these units and you still want one?! I bet one of your buddys would sell ya one cheap.
If you are looking for a budget wood furnace, Englander (http://www.homedepot.com/p/Englander-3-000-sq-ft-Wood-Burning-Add-On-Furnace-28-3500/100185844) makes one that gets good reviews, US stove, not so much, Daka, meh...

 

[actionjack]

lol I didn't mean those particular models but add on wood furnaces in general. Thanks for all of your help!

 

[brenndatomu]

Oh, OK, well FYI about the only box store add on wood furnaces worth looking at would be Drolet Heatmax or the Englander, in that order IMO. If you can pony a bit more cash up look at the Caddy line https://www.google.com/url?sa=t&rct...yOT-yZOFcEX91Brda5eMVYg&bvm=bv.77880786,d.b2U similar to the Heatmax only heavier duty materials.

 

[brenndatomu]

Oh, just re-read your OP. Better check with your local codes, in a lot of places a wood burner in the garage is illegal. Also, tying into existing duct work will reveal some safety clearance issues with the ducts I'd bet (for wood heat, not as is now)

Also, if crawl space is unheated you will need to insulate the heck out of the ducts to keep from losing all the heat to it

Just giving ya a heads up...

 

[JustWood]

I live in a tri-level and have this very setup.
Yes to the heat dump.
Blower does not need to run continuously. It will most likely run much of the time anyway except at the beginning and end of burn cycles.
I have about 10' of regular ducting out of plenum to wall of furnace room . then flex duct through wall into crawl space where it goes through a 15" , 14 foot long culvert pipe to tie into main house duct work.
The culvert after going through wall actually travels outside for 3' before going into crawl space. Snow will build up on the pipe so I know there is very little heat loss. This surprised me many years ago when I set it up this way. Thought I would have to spray foam the pipe to keep from losing heat, but not the case.
Agreed on spending the extra $ for a better furnace.

 

[actionjack]

OK good to know JustWood. But to brenndatomu's point I talked to my insurance agent and having it in the garage is against code, has to be inside or outside house. Guess I'm going to have to rethink my options now. I could easily put an outside add on furnace (would actually be easier), but man they are much more expensive.

 

[brenndatomu]

OK good to know JustWood. But to brenndatomu's point I talked to my insurance agent and having it in the garage is against code, has to be inside or outside house. Guess I'm going to have to rethink my options now. I could easily put an outside add on furnace (would actually be easier), but man they are much more expensive.

Use more wood too...might be worth a shot though, insulate the heck out it! Or build a well insulated doghouse around a regular wood furnace ducted into the house...?

 

[actionjack]

That is actually a really good option, the way my house/ductwork is laid out, I could build I little shelter right outside my kitchen and the amount of duct actually outside would be very minimal (maybe 1-2'), so I feel like the heat loss would actually be less than the original garage idea. I'm trying to find any pictures or actual installs where someone has taken an indoor wood unit and made it weatherproof and put it outside. Do you know where any are?

 

[brenndatomu]

I think there have been some on here, if not there is on that other woodburners site "AS", or check youtube...
Edit, better double check ins co again, some don't want a wood burner even outside! (time to shop for new ins if that is the case!)