Using Central Furnace to Heat Garage?

[Cornholio]

Hi all,

My name is Alan and I live in Ohio (west of Columbus). I'm a newbie here and I ran across this forum when searching other people's garage setups. I'm also a new home owner (just got my 1st house this year in May). I have a 2 or 2.5 car attached garage measuring approximately 40 ft. x 30 ft. x 12 ft. It is a finished garage (drywall all around, including ceiling). My house is all electric, so my options for heating the garage are limited. There is currently no 220/240V power in the garage either.

Does anyone know how feasible it is to tap off the ducting from the house's central furnace into the garage? Giving, the flow and volume characteristics of the existing furnace, I would think the furnace would need to be upgraded since there would be a pressure loss throughout the system.

This would be nice if I can get it to work because then I would also have A/C during the summer time because the garage gets hot as **** during the summer months.

Any input would be appreciated.

Thank you.

Alan

[Roadster]

Generally not advised, because the return duct could allow car exhaust vapors into the living quarters. I also think it is against most local building codes.

[gerry]

My old shop shares a supply duct with the house above it. Every time I mixed paint or used a solvent of some type, the smell would enter the house. I had considered buying a used trailer type packaged HVAC unit to feed just my shop. They are available around here for $300 or so

[DaveL.]

As stated above,not a good idea. Most,if not all building codes would strictly forbid it. I also have 30 x 40 attached. Here is how I heat and cool mine,17000 btu wall AC unit and a 75000 btu vented natural gas heater...works like a charm!
Welcome to the site.Have any pictures?

Dave

[Cornholio]

Thanks for your input everyone. I can see how it would be bad to duct it from the house's furnace. I just bought a Reddyheat 30-55K BTU propane torpedo heater, so I will use that for now. I will have to wait until daylight to take some pics because the lighting is poor for night time photography (only 2 100W incandescent bulbs). That's another upgrade I need to make.

Alan

[batmbl]

I, too am buliding a new attached garage. Got the same answer from my contractor -- building codes won't allow running a duct from living space to garage. Will probably go with portable units.

[ruby76]

I understand that a return line would "suck" in vapors from the garage, but what if you did not have a return line in the garage? Im asking b/c I DID tie into the HVAC duct in my attic and put a small single outlet into the garage. I close it in the summer to save AC, but leave it open in the winter. The cat lives in our garage when we are at work during the day so this heat duct allows the cat's water to not freeze. It basically just keeps temp above freezing.

As of yet, I have not smelled any exhaust/fumes etc from the garage in the house. Guess I might need to "uninstall" when selling my house from the sounds of it.

Jeremy :headscrat

[OldCarGuy]

The interpretation of the code is that there should be no openings between a garage and the house. And a hot air vent would breech the fire barrier between the two areas. If there is a fire in the garage, it could travel into the house through the vent.

[danski0224]

As stated above,not a good idea. Most,if not all building codes would strictly forbid it. I also have 30 x 40 attached. Here is how I heat and cool mine,17000 btu wall AC unit and a 75000 btu vented natural gas heater...works like a charm!
Welcome to the site.Have any pictures?

Dave

That pull down staircase in your pic is also against code because it is not fire rated.

[krooser]

I understand that a return line would "suck" in vapors from the garage, but what if you did not have a return line in the garage? Im asking b/c I DID tie into the HVAC duct in my attic and put a small single outlet into the garage. I close it in the summer to save AC, but leave it open in the winter. The cat lives in our garage when we are at work during the day so this heat duct allows the cat's water to not freeze. It basically just keeps temp above freezing.

As of yet, I have not smelled any exhaust/fumes etc from the garage in the house. Guess I might need to "uninstall" when selling my house from the sounds of it.

Jeremy :headscrat
the last house I owned had the shop heated with the house's gas furnace..never a problem or fumes.

[DaveL.]

That pull down staircase in your pic is also against code because it is not fire rated.

Elaborate please....

[danski0224]

Elaborate please....

A garage- especially an attached one- is a fire rated envelope. That explains the fire rated door to the home and the 5/8 type X drywall.

Those nice and convenient pull down stairs do not carry a UL 1 hour fire rating. I have never seen that in stock at a home improvment center- I don't think a residential access ladder company even makes one.

Anyways, the only thing keeping the potential fire in the garage away from the house is that flimsy 1/4 inch plywood- which will burn through pretty darn quickly.

Simply attaching type X drywall to the face of the ladder won't create a UL rating.

Drywall access panels (the square hole cut by the builder) retain the 1 hour rating, but the cheapo casing around the opening holding up the drywall does not create a 1 hour rated opening.

A sharp home inspector will pinch you on the problem.

[danski0224]

I understand that a return line would "suck" in vapors from the garage, but what if you did not have a return line in the garage? Im asking b/c I DID tie into the HVAC duct in my attic and put a small single outlet into the garage. I close it in the summer to save AC, but leave it open in the winter. The cat lives in our garage when we are at work during the day so this heat duct allows the cat's water to not freeze. It basically just keeps temp above freezing.

As of yet, I have not smelled any exhaust/fumes etc from the garage in the house. Guess I might need to "uninstall" when selling my house from the sounds of it.

Jeremy :headscrat

Any ducts passing through a fire wall need, at a minimum, a fire damper in the metal ductwork. There are also specifications describing the type of sleeve for the damper and attachment methods. The rating of the damper assembly must match the rating of the wall assembly.

That is why, besides the fume issues, a duct off the furnace into the garage is not allowed.

Ductwork is allowed in a garage if it is concealed by drywall, but the duct cannot breach the drywall into the garage.

I know people that have done it, but it isn't smart.

[DaveL.]

A sharp home inspector will pinch you on the problem.[/QUOTE]

hmm...I wonder how that got by my new home final inspection. I'll give my builder a call tomorrow and have him replace'm.

Thanks Chief.

[danski0224]

Ask him to show you the UL fire rating on that pull down staircase. Bet he can't find it.

[Hugh Morrow]

Radiant heat from a gas tube heater or oil over electric is the only safe way I have found. If any wood work is being done I would suggest oil over electric as wood fiber in the air could be a real hazard. I do autobody and use the gas fired radiant tube heaters. Had them for over twelve years and no problems. Stopped at a friends place and still has a blower stye furnace and brought back the memories of dust being blown around and into everything. No wonder a lot of my old work buddies are on the other side. The tube heaters seem to be good on fuel as the combustion air is taken from outsice which reduces the big bang stuff. I have not checked in a while for what is avialable but most are not rated as explosion proof.

[DaveL.]

Hugh - How do those radiant tube heaters work in a garage with 8.5 to 9 ft cielings ? Is there a concern about damaging paint on vehicle (especially a Corvette) parked directly beneath it ? My buddy has one of those in his repair shop and if I remember correctly they get pretty hot.

p.s. sorry Luke..we got a little off topic here.

[Roadster]

Ask him to show you the UL fire rating on that pull down staircase. Bet he can't find it.

Do all pull-down staircases installed in a garage need to be fire rated? Genuinely curious. I'm considering installing a Rainbow Attic Stair in my garage, and I have no idea what typical building codes say.

[Stuart in MN]

Most radiant tube heaters are designed for shops with 12' ceilings or higher, but there are some that will work with 8 or 9 foot ceilings. Here's one example: http://www.rg-inc.com/caribe-infrared-garage-heater.htm

The thing about fire rated attic stairs can a concern if your garage is attached to the house. If the garage is detached it shouldn't be an issue, as long as there isn't living space above. There needs to be a fire rated barrier between the house and garage that's usually accomplished with fire rated sheetrock. If the attic is common to the house and garage, the attic stairs will need to be fire rated. I think a lot of houses have a layer of the fire rated sheetrock up in the truss area to separate the garage and house attics, in which case the stair would probably be okay.

As usual, your results may vary... :) I'm not an authority, so double check with your local zoning board.

[DaveL.]

I spokewith the local building inspector on this matter today. He said he would not fail my home inspection for using those type of stairs in a garage even though it is a 'gray' area. He said if I was terribly concerned about this (which I am not) I could screw a sheet of drywall to the door. I have anywhere from 5-6 vehicles in my garage at any given time. If I have a fire bad enough in the garage to threaten a 2' x 4' section of the cieling, the gas in those vehicles will ignite a fireball so big it won't matter if I have a set of wooden pull down stairs. Trust me,I've got more to worry about in my life.
Enough said... :willy_nil

[danski0224]

It is good that your inspector granted you some leeway.

The point concerning the number of vehicles and the gas they contain is also valid.

That doesn't change the fact that the pull down stairs are not to code for an attached garage, an attached sheet of drywall will not bring them into compliance, and a more stringent inspector could make life miserable for someone that really wanted those stairs- either at the time of installation or at the time of sale.

[Roadster]

Do all pull-down staircases installed in a garage need to be fire rated? Genuinely curious. I'm considering installing a Rainbow Attic Stair in my garage, and I have no idea what typical building codes say.

bump

danski, what makes pull-down stairs fire rated or not? What specifically in the code is being violated?

[danski0224]

They have to have a UL fire rating- just like 5/8 drywall and the fire door that is installed between the garage and home.

By installing the pull down stairs, unless you use UL listed ones, you are destroying the fire rating of the ceiling assembly. Some inspectors catch it, some do not.

It is not an issue if your garage is detached from the home.

[Roadster]

They have to have a UL fire rating- just like 5/8 drywall and the fire door that is installed between the garage and home.

By installing the pull down stairs, unless you use UL listed ones, you are destroying the fire rating of the ceiling assembly. Some inspectors catch it, some do not.

It is not an issue if your garage is detached from the home.

Thanks for the info. My garage is not detached, so it looks like I need to get an attic stair with a UL rating.

I think the same manufacturer makes a UL-rated stair, but I don't think it's tall enough for my garage.

[danski0224]

Thanks for the info. My garage is not detached, so it looks like I need to get an attic stair with a UL rating.

I think the same manufacturer makes a UL-rated stair, but I don't think it's tall enough for my garage.

They probably offer an extension kit.