New wood Furnace Install w/ Pics

[jdew1920]

When I was researching and getting ready to install this I was able to get a lot of good info from this site. Thought I would share my installation and hopefully help someone else in the future.

Because we are on natural gas which is somewhat reasonable in cost, although has gone up a lot in the past 5 years or so, and this is my first attempt at heating with wood I went with just about the lowest cost wood furnace I could find which was the Daka furnace. All the comments I saw from owners of these were positive. No frills, but effective.

Our house is an 1800 SF ranch built about 30 years ago, with the furnace installed on the far end of one side, so there is a long duct run to reach the opposite end. Wall insulation is average, but it is sealed up pretty good since I've replaced all the windows and doors since we've lived here and sealed everything up pretty tight. I also added about 8" of cellulose to the attic last year which helped a lot too. I was able to use an existing masonary (clay lined) chimney that was built with the house but never used. All I had to do was drill through the clay liner to access the chimney.

I installed the furnace in parallel with our main furnace. It has a single 500 CFM blower on it that actually pushes a decent amount of air, the blower is activated via a thermodisc on the wood furnace. I installed a relay to the thermodisc also, so when the blower on the wood furnace is activated it activates the blower on my main furnace via. The gas furnace is a newer Rheem with variable speed blower. I have the "fan on" dip switches set to low (500CFM) - the two blowers combined have no problem providing good air flow through the home. I might in the future install a plenum fan control to control the gas furnace blower but for now this works pretty good. I did connect the wood furnace to the main return duct of the gas furnace.

It has no problem keeping the house warm so far. A couple of weeks ago we were down to 0 and the house was at 70 whith just a medium sized fire. I've actually been suprised at how easy it's been to keep the house comfortable, right around 70. I was worried it would always be either too hot or to cold based on my experience at my in-laws where they had an old Thermopride wood furnace along side an oil furnace. Mainly I've been building a decent fire in the morning to get things heated up and them just keeping a small but hot fire most of the day, by adding 3 or so logs every few hours when it gets down to coals. I have a magnetic thermometer on the stove pipe that I've been using as a guide to get a feel for the furnace. generally when the fire is in full swing it is reading 350-450. I've got a litle digital thermometer with remote sensor sitting in one of the registers in the family room so I can check the temp and see if it's time to add some wood. Because of my worry about creosote build up I haven't been dampering the fire down too much at night. I did do that one night, where I loaded up a bunch of wood and reduced the draft and in the morning I did have some coals left, but I could also see the creosote build up on the walls. Since then I have just been adding a normal loading of wood and setting the draft for what ever is required to maintain a decent fire.

My wood is all elm complements of dutch elm disease. It is dry, and It seems to burn pretty well but then again I can't really compare it to anything. Although I will say it is kind of a pain to split - even with a spltter. I did run the wood furnace at my mother in laws last week when we visited - there's some left over hard maple from my father in law before he passed a way and I did notice that it seemed to last longer.

All in all I'm happy with it. After a couple of weeks of use though I am coming to appreciate the concept of a boiler with storage. I hate going to bed knowing that my fire will die out and the gas furnace will come on. Maybe in a few years....

I attached some pics.

 

[jdew1920]

Forgot one more thing. I've been monitoring the smoke coming out of the chimney. Generally very little smoke, almost none when in the middle of a burn. Definately smokes some after starting a fire or loading but doesn't last too long.

 

[laynes69]

Don't worry about creasote on the walls of the wood furnace. Its normal. You air pushing cool air around the firebox. We run ours 24/7 w/o any issues. As long as you have a good fire damping it down some for night won't hurt a thing. Looks good, I would consider getting rid of the flexible take off in the future. Also make sure your clearances are covered with the ductwork, in case of a power outage.

 

[smokinj]

Looks good! great way to link the two furances to most people dont do this and have all kinds of problems! (good install)

 

[Fuel]

Don't worry about creasote on the walls of the wood furnace. Its normal. You air pushing cool air around the firebox. We run ours 24/7 w/o any issues. As long as you have a good fire damping it down some for night won't hurt a thing. Looks good, I would consider getting rid of the flexible take off in the future. Also make sure your clearances are covered with the ductwork, in case of a power outage.

which flexible takeoff, I didn't see one on there.

 

[laynes69]

Fourth picture over. Its between the plenum and the takeoff.

 

[Fuel]

oh i c it, my system has one of those, i should get rid of it before i hook up my furnace. DIdn't think of that, thanks

 

[jdew1920]

Not sure what you're seeing but I don't have any flexible take offs. Are you talking about the vibration isolator between the plenum & duct run? I did think about that, I checked with the manufacturer and they said you don't need to remove, but I do think if you need 6" clearance above, you certainly probably shouldn't have that there. I'm sure it's heat resistant up to a degree, but not too much. I did look into replacing it and found another type that is good up to 500 deg.

Also, clearance wise I am in good shape. They specify 6" clearance above plenum & for first 6' of duct run. I brought them down to 3" and spaced out the sheet metal to allow the reduction. Had it inspected and had no problems with the mechanical inspector.

 

[laynes69]

Wasn't sure if that was a boxed return air, or sheetmetal to reduce clearances. I figures it was to reduce the clearances in the ductwork. Looks good! The vibration isolator is rated for up to 200 degrees from what I have read in some other posts. Thats why I asked. Also did you run a seperate return air? Looks like it, but not sure.

 

[Fuel]

does a guy have to run a seperate return air, i wasn't going to, just pull off of the current one right before my natural gas furnace over to the wood furnace

 

[jdew1920]

Mine was tied into the existing return air of my gas furnace. The Daka has a built in back draft damper in it so when the gas furnace is running alone it can back feed through the wood furnace.

 

[laynes69]

I see. Fuel the best way when tying in like that is to add dampers. That way if the woodfurnace is running full bore, and the central furnace decides to run, your not pulling the hot air through the furnace. You can ruin coils, and electronic components not made for the high heat. Its important. To get around it, you can install a single cold air return for your furnace, you would just try to locate it centrally in the home. But dampers work just fine when sharing.

 

[Fuel]

so put dampers in the return air side, how do u do that with a trunk line like this one

 

[Fuel]

btw, sorry if i am jacking ur thread jdew1920

 

[jdew1920]

Mine was tied into the existing return air of my gas furnace. The Daka has a built in back draft damper in it so when the gas furnace is running alone it can back feed through the wood furnace.

Sorry - I should of said it "can't" backfeed through the wood furnace.

I was going to install another damper in the main furnace plenum but instead decided to just run the main furnace blower on low speed all the time with the wood furnace. Plus, the 8" ducts going into the plenum have 90's on them point up & towards the main trunk line so if for some reason the main furnace blower didn't come on I don't think I'd have a problen. If I decide to try to run the wood furnace w/o the main furnace, or rely on a plenum fan control to turn on the main furnace blower than I would add a damper in the plenum.

 

[Fuel]

where do u get a plenum damper

 

[jdew1920]

Best bet would probably be an HVAC supply shop. I looked around online and they are not that easy to find - I think I found one and it was around $100 - maybe more for the size I would need. I think with a little creativity you could make one yourself. I didn't put one in since my A-coil is mounted up high and I didn't have room to put it in above it (they recommend putting it above the A-coil) - that's why I ended up just setting my gas furnace fan to run when the wood blower is on. I did install mine with 90 deg elbows on the ends in the plenum to direct the air up (per the install directions) but I also angled them to blow the hot air out into the main duct run. Also don't forget you should have a damper in the wood side somewhere so you can't pull air through it like laynes69 mentioned.

Have you checked the US Stove website for the install manual? You can download it there if you need it.

 

[Fuel]

so i could make the two share the return air and just put a baffle in the main return air line in the direction of flow much like u did with the elbows for the supply line of ur furnace into the plenem

then put two dampers in the supply 8" ducts of the wood furnace that way if the gas furnace kicked on when the wood furnace was running it couldn't backdraft but they could both use the same return air

Also, i wouldn't have to run the gas furnace fan on with the wood furnace fan

i hope u got all this!

 

[Fuel]

Here is a picture to try to explain what i just said.

I know it is kind of a crude picture but just threw it together to try to get my point acrossed. So with it set up like this would that let either furnace run on its own or at the same time without any problems or backdrafting

 

[jdew1920]

I would suspect that would work, I think the baffle definately would help - keep in mind I am not an expert though. In fact I thought of hooking up my retrun similar to how you are drawing (with a baffle) but ended up not doing it that way since I can set my gas furnace blower to run a a low speed (500CFM). Only thing missing from an ideal set up would be the damper in the gas furnace plenum but I suspect most people don't add them. I say give it a shot and see how it works.

 

[Fuel]

i was wanting a baffle in the gas furnace plenum too but much like u i just don't have the room for it because of my AC a coil i think that i am going to set it up like this and completely shut off the gas furnace and see if the wood furnace can handle everything by itself first, then go from there

 

[laynes69]

Without installing a baffle in the plenum or above the central furnace, the heat will backfeed into the furnace. You will get a hotter heat if you install a backdraft damper in the plenum, then if you would run the central furnaces fan on low with the woodfurnace operating. You need to build some pressure in the ductwork. It will be lost in the central furnace w/o a damper.

 

[smokinj]

looks like its well done!

 

[jdew1920]

Without installing a baffle in the plenum or above the central furnace, the heat will backfeed into the furnace. You will get a hotter heat if you install a backdraft damper in the plenum, then if you would run the central furnaces fan on low with the woodfurnace operating. You need to build some pressure in the ductwork. It will be lost in the central furnace w/o a damper.

I agree that a damper in the plenum will probably be required if only using the wood blower. But, I can say my Daka with 500 CFM blower combined with my gas blower at 500 CFM works real nice, and supplies nice warm air out of the registers.

 

[Fuel]

nevermind on this one