Best Wood Heating Option for 3500 sqft New Construction

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cchavies7

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somerset, ky
Hi all, new to this site. Looking for some advice. I am building a new home this year, 3500 sqft with walk out basement and 2 stories above ground. I am looking into the best wood heating options, I will have a heat pump for backup heat but plan to use the wood heat as the main heat source. I am currently leaning towards a forced air wood furnace unit in the basement but have realized the EPA regulations have complicated the search. What has been your experience with the best type of unit to heat a home in this size range and what is the best product still available to purchase with the EPA regulations?
 
That's a biggish house but built new in Kentucky shouldn't have a huge heat load. I would likely first consider a Kuuma add-on furnace, that would use the same ductwork.
 
Wood furnace in the basement is job security. Always something to clean, like a 30 foot chimney. I'd go with an outdoor boiler. Run pex lines in the floor. No maintenance, no smoke in the house, no worries.
Are the outdoor boiler units affected by the EPA regulations in the same way the indoor furnaces are?
 
Everyone has their preferences & priorities - but seems one that has already been mentioned by the OP is in the basement. And furnace. And with existing ductwork - a Kuuma fits all that. Not sure multiple distribution systems would be a good choice of budget. And with a Kuuma & dry wood there should be no chimney cleaning needed.
 
Are the outdoor boiler units affected by the EPA regulations in the same way the indoor furnaces are?

Yes. Well, they are subject to them also if that's what you mean. Even with an EPA boiler you can still get some smoke & creosote with periods of idling.
 
I'd really look into the insulation of the home prior to jumping the gun and choosing a wood stove...

Sorry if you've already chosen to spray foam your new build, I didnt catch that in your intro or question.

Stay away from an outdoor stove. Build the house (open floor plan) around the insulation and woodstove.
 
An outdoor furnace can be used well with ductwork.Just run pex lines to a place right in front of your fan and put a heat exchanger in the ductwork.Not hard to do.If you are going that route,put in the lines and exchanger as you build.
There are two ways to look at this and neither are wrong.With an outdoor stove,you keep fire,dust and dirt outside of the house.You don't need to split your wood as small,either.Plus,no chimney maintainence
on top of your roof.Insurance may be lower with this setup,too.With an inside furnace,you get heat quicker since you don't have to heat the water first and you don't have to go outside in the rain or snow to fire it.It's whichever you want.
 
Are you saying 3500sf footprint, or 1200sf footprint?

If you go with a forced air furnace, you want separate ducts for the backup furnace. Trust me, learn from my mistake. Also, don't waste your money buying a cheap furnace. Get one with full factory installed digital controls for the damper and fan and the biggest firebox you can.

And if you have a furnace in a basement with 2 stories above it, you're looking at what 30' of class A chimney? Yeah, that's gonna overdraft like crazy and you'll be messing with a barometric damper to fix it.

The outdoor boiler is the solution, if you can spend the money.
 
Are you saying 3500sf footprint, or 1200sf footprint?

If you go with a forced air furnace, you want separate ducts for the backup furnace. Trust me, learn from my mistake. Also, don't waste your money buying a cheap furnace. Get one with full factory installed digital controls for the damper and fan and the biggest firebox you can.

And if you have a furnace in a basement with 2 stories above it, you're looking at what 30' of class A chimney? Yeah, that's gonna overdraft like crazy and you'll be messing with a barometric damper to fix it.

The outdoor boiler is the solution, if you can spend the money.
I'm new to the wood furnance world - i apologize if my questions seem stupid, i am definitely not very educated about this stuff. What is the advantage of the separate ducts? That was actually going to be one of my next questions after I found a good furnace to purchase. I would like to avoid having returns and vents all over the place if possible so i was unsure if the separate ducts were a necessity or not.
 
I'm not sure why separate ducts would be needed either. Maybe in some cases of retrofitting an add-on furnace to a system that is already there - that might make challenges that makes putting in a new trunk for the new unit the easier way to go. Wood furnace ducting does generally have stricter requirements re. what they're made out of & clearances - but if you design to those you should be good. Dampers would be needed in the tie-ins to make sure that say your wood furnace doesn't feed hot air through your heat pump stuff. I have hot water & not hot air or a furnace so no hands on experience, but I think the majority use one duct system. At your stage the main thing to do, after narrowing down a furnace choice, is find someone who can make sure you get your system design right. Also I think all furnace builders have input or stuff in their manuals about install basics.
 
I think a question also should be what amount of wood you have available seasoned/unseasoned storage inside outside?


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I'm new to the wood furnance world - i apologize if my questions seem stupid, i am definitely not very educated about this stuff. What is the advantage of the separate ducts? That was actually going to be one of my next questions after I found a good furnace to purchase. I would like to avoid having returns and vents all over the place if possible so i was unsure if the separate ducts were a necessity or not.

There are several circumstances where your wood furnace is producing heat but not enough to maintain a comfortable temp. If your backup heat uses the same duct, you can't safely run them both at the same time. That's because the wood furnace needs to dump the heat it's creating and if the backup is running when the wood furnace wants to kick on you have a problem. Either open the ducts and let the two fans fight each other, hoping the fans don't burn up or worse, damage one of the heat exchangers.

Sure, you can do the dampers (BTW I have to use powered dampers ~$400), and at this point that's my only option, but it's far from ideal. I will watch it closely and add controllers and relays (~$200) to make the best of a bad situation, but YOU don't need to do that since you have a clean slate. By the way, the only way I can figure to make it work, even with the dampers and controllers, is to set the backup thermostat a few degrees below the desired house temp. That way the backup only comes on when the wood furnace is low on fuel so the two are less likely to be running simultaneously though it's inevitable they will to some extent. You sure wouldn't want the backup kicking on while your wood burner was mid-load and making a lot of heat but it would do just that if both were set at 70* on a cold day. Now when you come home from work your house is colder than you like because your wood furnace is down to a few coals and your backup is set to 65* to prevent the two from running simultaneously. I'm planning to program the thermometer on my backup heat to run at 65* until 4pm or so and then heat back up to 70* because by that point the furnace is down to a few coals.

If you had separate ducts, you would set your backup at the desired temp and the wood furnace would do what it can and the backup will keep your house comfortable. The other thing I would do if I were building from scratch is build a furnace room on the exterior wall of the house with an exterior door so all the mess stays contained. Mine is in the basement garage which is tolerable but I definitely would not want the mess within the basement.

In your position, you can -and absolutely should- add a second set of ducts even if it's just a simple setup that doesn't hit every room. Have it dump 1/3 in basement, 1/3 main floor, 1/3 upstairs in a central location if needed. Your backup heat will have a duct system and it can be used to distribute the heat using the blower if needed.

I'm not sure of your climate but when it gets really nasty here we have to switch to the gas furnace. The wood furnace would do 80% of the work if we could run both on those -30 wind chill days but instead it sits cold. Last billing cycle just a handful days of having the gas on cost $40.
 
If you're building a large home from scratch and you live in a nasty winter climate, build the home around a CENTRALLY LOCATED stone/brick chimney and a full size Blaze King/King or other high efficiency large firebox wood stove of your choice - put a compact Super Hot NatGas boiler in the basement so you have NatGas hot water heat piped into the slab and all the distant rooms for backup - forced air is last on my list of pleasant living environments - the way homes are built now wrapped in a plastic bag, keeps everyone breathing re-circulated indoor air, and locked into a mortgage paying the man each month to stay warm:

"Life in New England during the winter was hard. Many of the homes there were literally built around a fireplace to keep all the heat generated and stored within it’s masonry in the home."
A central chimney
August 24, 2015 by Noah Bradley 5 Comments

https://handmadehouses.com/a-central-chimney/
 
If you're building a large home from scratch and you live in a nasty winter climate, build the home around a CENTRALLY LOCATED stone/brick chimney and a full size Blaze King/King or other high efficiency large firebox wood stove of your choice - put a compact Super Hot NatGas boiler in the basement so you have NatGas hot water heat piped into the slab and all the distant rooms for backup - forced air is last on my list of pleasant living environments - the way homes are built now wrapped in a plastic bag, keeps everyone breathing re-circulated indoor air, and locked into a mortgage paying the man each month to stay warm:

"Life in New England during the winter was hard. Many of the homes there were literally built around a fireplace to keep all the heat generated and stored within it’s masonry in the home."
A central chimney
August 24, 2015 by Noah Bradley 5 Comments

https://handmadehouses.com/a-central-chimney/
I'm not sure I follow. First, a modern high efficiency EPA stove will struggle to operate correctly whilst attempting to heat soak a 10k lb masonry chimney. They require an insulated 6" (?) class A chimney specifically so they keep the heat within the chimney. Second, I'm not sure why it makes sense to have 1) a system to do inground heat with the boiler and 2) a second natural gravity heat system. If a person is spending the money for the floor heat why wouldn't he just have a large storage unit fed by a wood boiler and a backup boiler?

Either way, neither of those systems has anything to do with building a massive fireplace center mass and using the mass of the chimney to store heat.

Not trying to get into a pissing match, I just don't understand what you are saying.
 
On the road, I really don’t understand why you recommend two separate duct systems. We grew up with a lot of combination wood/oil furnaces. I have seen dozens that have two thermostats but use the same ductwork without any problem for forty years. It’s definately not new technology. Wood is downstream of the oil so that the oil furnace is not overheated by the wood.
 
If I had a house that big it would either be a wood boiler or furnace with several zones. Is 3500 sq ft including the basement?

My place is about 1400 sq ft, 1 floor. It's well insulted (R21 walls, R60 ceiling). When it drops in the -10* area or colder it doesn't get all that warm in master bathroom (furthest from the stove). I keep the floor heat on at 65*, no sense in freezing just to save $20 of natural gas.

If you do a setup without air movment (IE floor heat), put in an HRV at least. Air movement is a good thing.
 

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