Heating Garage from Room Above

[tammrack]

How can I heat the garage from a woodstove located in a bunkie above the garage without compromising the vapor barrier/retarder in the garage ceiling?

Details:

We are building a 30 x 30 garage with a bunkie above the garage. All walls will be insulated to a min. of r24. The garage doors 9x8 will be insulated to r17. The garage ceiling will have a vapor barrier/retarder and insulation to prevent any vapors, gases or fumes from entering the bunkie above the garage. Being in northern Ontario, I will be heating the bunkie with an EPA approved wood stove. In the winter time, I would like to transfer some of the heat from the upstairs bunkie to the garage below without compromising the vapor barrier/retarder. Putting in standard duct work between the bunkie and garage would comprise the vapor barrier.

"Building codes do not allow any penetrations between the firerated ceiling and wall assemblies in a garage below a habitable room above that would allow any noxious gases or flames to enter a bonus room above a garage."

 

[rickairmedic]

Tammrack you could install a radiator behind the woodstove and a second radiator down in the garage with an air handler unit to blow air through the radiator downstairs put a pump in the water lines running between the radiators . The wood stove will heat the water in the radiator upstairs and the air handler downstairs will blow the heat the downstairs radiator into the garage . I have a customer who has a wood boiler outside with a radiator in the ductwork next to his furnace and heats his house most of the winter that way.

Rick

 

[redsky49]

"Building codes do not allow any penetrations between the firerated ceiling and wall assemblies in a garage below a habitable room above that would allow any noxious gases or flames to enter a bonus room above a garage."

The above referenced code does not prohibit all penetrations of the rated assemblies, only those that do not prevent the transfer of fumes. What also is required (dependent on your specific code adoption) is that the fire rating must be maintained. That is, any penetration of the rated assembly would be both fire and smoke dampered, with fire stopping applied to any gaps or openings of the assembly. Obtain written verification from your local permit authority prior to start of work. All codes are subject to local interpretation and that means the door is open to a lot of curious local judgements. Be clear with local authorities before proceeding.

That being said, heating the lower level with a wood burning stove mounted above would be quite a challenge.

Conventional wood stoves heat primarily through radiation and are designed to heat the room they are located in. Room air is heated only to the extent that it passes over the hot surfaces of the stove.

Convection type wood stoves utilize a double wall construction that encourages room air flow due to the open chamber design of the casing. Some of these units may also incorporate a fan to aid in air circulation.

Advanced design wood stoves (these are relatively expensive) use both catalytic and non-catalytic design technologies to achieve very high combustion efficiencies and, at the same time, reducing creosote and particulate and carbon monoxide production. Some of these stoves achieve an EPA efficiency of 80% or better.

In all of these cases, the majority of heat is either radiant or convective and would be difficult to transfer to an adjacent space, particularly to a space below the occupied space. If you try to utilize transfer of the bunk room air via a fan-forced system you face several problems, not the least of which is that you will be prohibited from returning that air to the bunk room.

I am aware of a system in the past that utilized a strap-on coil to capture or recover heat escaping from the flue, but that was an elaborate system that managed only a few thousand btu at considerable cost and complexity. Probably not pertinent to your situation.

I am a great fan of alternate energy sources, but I cannot see how this could be safely done and at a reasonable cost. However, there might be an alternative. Several manufacturers produce wood fired boilers. A single boiler could easily heat both spaces and the distribution piping would be simple enough to be self-installed. As a bonus, radiant hot water heat is one of the most comfortable types of heat, far superior to the performance of a wood stove. Depending on the layout of the space, as few as 4 or 6 radiators might do the job. One step up might include a pellet-fed system, especially if the space is not occupied for extended periods and you wish to maintain the space temperature. The service life of a cast iron boiler might also exceed the life of your garage. There are several benefits to this type of system. The downside is that there would be a considerable increase in the upfront costs, though not prohibitive.

Hope this provides some help.

Offered only as opinion

 

[tammrack]

Thanks guys for all the suggestions and ideas...I found a used electric furnace that I'm considering using to help heat both areas (bunkie upstairs and the garage below) ...I will still have the woodstove upstairs as my primary source of heat...the only trick is... if I place the furnance in the garage I have to direct vent the furnace ouside to prevent any exchange of air between the garage and bunkie...