Garage heating with wood

[Jon_E]

I'm in the process of building a new garage/workshop, 24 x 36 feet. It will have 10' ceilings and a second floor with kneewalls. Two insulated garage doors, a few small windows, spray foam insulation. I am planning on putting radiant tubing in the slab, with a small heat exchanger and a single heat zone. I currently heat my house with a Central Boiler OWB but it is about 150' away from the garage and I will have to cross my water line and sewer line with PEX tubing from the OWB if I want to use it for heat in the garage. Not sure I want to spend $2000 on PEX tubing for that run.

What I am looking for is a different solution, something that is separate but will still allow me to burn wood. I want to compare costs. I was thinking of a very small woodboiler/stove with a water jacket, something that can be placed inside the garage. I don't know of anything that small. The garage will only be heated to around 60 degrees even in dead winter, I do not like to work in warmer temperatures but I want to keep the floors warm so that my tools don't rust. Are there any possibilities for a small system such as this?

I am also considering a heat-pump or even an electric water heater with a solar panel, although it's not wood-burning, it's likely to produce enough heat for my garage.

 

[cityboy172]

Check code to see if you can actually put a wood burning appliance in a garage.

 

[newyorker]

in my opinion i would buy the pex if your cb can handle the load one wood burning appliance is enough my buddy has the same size garage spray foam walls and radiant floors heats it with a 30 gallon water heater lp

 

[stee6043]

How often will you be in your garage? In-floor systems have a long recovery time. If your plan is to always keep the garage warm this would work well but if you plan to only heat it when you're out there you will likely be disappointed.

If it were my garage I'd invest in super-insulating that garage and then heat it with electric or small nat. gas / propane rig. You won't need much if you do the insulation right...

 

[GENECOP]

Seton builds the UGLI, check it out...

 

[BoiledOver]

This is a small unit.

(broken link removed to http://antiquestoves.us/shop/water-heaters/35-wood-fired-stainless-steel-water-heater.html)

 

[Boil&Toil]

I am also considering a heat-pump or even an electric water heater with a solar panel, although it's not wood-burning, it's likely to produce enough heat for my garage.

Insultate the <bleep> out of it [not forgetting the floor!] and everything gets easier.

Not sure how you are getting to $2000 for 150 feet - that horrid crap in sewer pipe? Check the stickies for the "build a foam box and foam it" method, [Title is "Underground Lines, not the place to skimp"] which should price out a good deal lower (and work better), I think. $500 or so for XPS, $300 or so for pipe, and a few hundred at most (typically a buck a board foot, or so) in foam to fill (which can be quite a small amount if you build it from the XPS sheets without a lot of void space). Don't forget to insulate the supply and return from each other fairly well (one thing the sewer-pipe version does very poorly, and one reason I won't be getting any.)

If you are considering "an electric water heater with a solar panel" you should consider solar hot water panels and a small solar pump (and a PV panel just for the pump) - it is FAR easier/cheaper to get heat (directly) from sunshine than electricity from sunshine. Electric backup is easy to arrange, but expensive to run when it's needed.

A good cold weather heat pump is now in the "cost competitive with bought firewood and pellets range", at least according to the Vermont Fuel Price Report, and Vermont electricity is expensive, relatively speaking.

I would suggest a small indoor type boiler/waterheater placed in a shed 15 feet or so from the garage, rather than putting a solid fuel burning appliance in the garage. Or (check your codes) possibly put in a walled off (2 hour fire rating wall) sealed (no fuel vapor penetration) room at the corner of the garage with access from the outside only.

But I think you can make an affordable connection to your current boiler and that will be the "best."

 

[BoilerMan]

I would echo what has been said, if you want it heated all the time radiant is that way to go. Solar and some type of electric backup would be quite cost effective in that situation. I'd consider some type of forced (scorched) air type of wood heater if you plan on letting it go cold when not in use. Fast recovery, and nothing to freeze.

Insulation is the best investment one can make in a building IMHO. You may be able to insulate cheaper with Roxul and sheet-good insulation on the inside of the studs, then metal/osb for your interior walls. Tape all the seams with Venture tape and you will have a very tight building, this is how I built my house, 2x6 with fiberglass R19 (Roxul was not on the market yet) and 1.5" Polyiso inside of that taped with foil tape.

Sprayfoam between wood studs does nothing to address the thermal bridging of the stud itself. Sheet-good foam does and is less messy overall. Spray foam has many useful applications I'm just not sold on wall insulation in new construction to be one of them.

TS

 

[brenndatomu]

Yea, chances are local code/ins. co. won't allow a burner in the garage. Spending the money for a line to connect to the CB would by far be the most elegant solution here, IMO. Only have to tend to one fire that way too. Could do the foam ditch line install like was suggested...

 

[bigbobs]

I have a Tarm wood boiler which is around 70,000 BTU/hr I can sell you for $500.00. I pulled it out of a house that was sold and the new owner didn't want it. I was told it was in working order when removed. I can bring it up to Killington, Vt area or you can pick it up in SE NH where I live.

 

[brenndatomu]

I have a Tarm wood boiler which is around 70,000 BTU/hr I can sell you for $500.00. I pulled it out of a house that was sold and the new owner didn't want it. I was told it was in working order when removed. I can bring it up to Killington, Vt area or you can pick it up in SE NH where I live.

Stonefire may be interested in that ?...https://www.hearth.com/talk/threads/vigas-or-empyre.136451/

 

[Jon_E]

My woodworking shop will be in the garage and it will be heated all the time. Even if I'm not in there I want it to stay climate-controlled. I looked up the thread on the foamed-in-place PEX, that sounds like a lot of work but definitely cheaper. I am not 100% sure about the insulation of the garage itself. I looked into SIPs but seemed way too expensive for a garage. I refuse to use fiberglass of any kind. The Roxul stuff seems nice but there's still thermal bridging unless you have a continuous sheet of insulation either inside or out.

Thanks for the suggestions. I am leaning toward the connection to my existing boiler, as the manifold and heat exchanger won't take up a lot of space and I don't need to run water out to the garage. I am going to put solar panels up but they will be to offset electricity costs, so they will be grid-tied PV. I am also going to look into a heat pump, trying to figure out how I can do heating and cooling with a heat pump if I have radiant flooring. Run HW through the floor tubes but have a cold-air discharge like a window AC unit for the summer? Have to do more research. Also would like to have some sort of dehumidification.

As far as spray-foam - when the term "board-foot" is used, does that mean the sprayed thickness or the finished thickness?

 

[atvalaska]

http://www.cchrc.org/ use this for building to keep warm.... finished... bf = 1" x 12"x 12"....$1.30 a sqf in these parts

 

[Boil&Toil]

My woodworking shop will be in the garage and it will be heated all the time. Even if I'm not in there I want it to stay climate-controlled. I looked up the thread on the foamed-in-place PEX, that sounds like a lot of work but definitely cheaper. I am not 100% sure about the insulation of the garage itself. I looked into SIPs but seemed way too expensive for a garage. I refuse to use fiberglass of any kind. The Roxul stuff seems nice but there's still thermal bridging unless you have a continuous sheet of insulation either inside or out.
...
I am also going to look into a heat pump, trying to figure out how I can do heating and cooling with a heat pump if I have radiant flooring. Run HW through the floor tubes but have a cold-air discharge like a window AC unit for the summer? Have to do more research. Also would like to have some sort of dehumidification.

As far as spray-foam - when the term "board-foot" is used, does that mean the sprayed thickness or the finished thickness?

Cellulose and either double-offset studs or "Larsen trusses" (or "wall trusses" as that article would call the way I'd do it) are alternate approaches to insulating well with limited thermal bridging.

Other than (so far all I've found being trés expensive) outside-air-cold climate air to water (or water to water) heat pumps, best I've come up with on the heat pump line would be a cold-climate air to air (commonly available and reasonably priced - any decent one can heat, cool and dehumidify all in one package) and something like the Nyletherm (from ebay and Tom in Maine) air (but not very cold air, at least as I understand it) to water heat pump for getting heat into the floor. Possibly an array of fintube in front of the blower on the air-to-air would work, but it might be sketchy.

AFAIK "board foot of foam" is after expansion.