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heating attached garage.
- Thread starter byrd
- Start date
Finley
Well-known member
im curious as well, mines only a 240 ft single car though.
Finley
Well-known member
i wouldnt think fumes would be too much of an issue if you just ran supply and not returns.
rickairmedic
Well-known member
I will only say it is completely against code to attatch ductwork from your home HVAC system to your garage . I will also add that the system in your home was set up to heat and cool a certain amount of square footage and adding your garage into the equasion will adversely effect the heating and cooling of your main living areas . There are many many options available to heat or cool a garage space and this unfortuantely isnt one of them . I dont know the actual code numbers but I do have the books here next to me if you need them just know that it is against code to do this .
Rick
Rick
Finley
Well-known member
fair enough. i'll continue to use my weak electric space heater. ignoring code affects my home insurance, so thats a no go. maybe a propane heater is in the works.
now.....to tackle the a.c. issue.
now.....to tackle the a.c. issue.
I had several HVAC people assess my 3-bay attached garage and most suggested I could tap into my home heating ducts and run a line or two into the garage if desired. They all indicated this would be best for supplemental heat only but none suggested it was against code. One contractor was going to install a separate thermostat and dampener in the overall system so I could set a different temp for the garage vs the rest of the house.
I ended up getting two Qmark PH-5HW electric heater units based on research I did here. I cannot easily get a gas heater installed as my MBR is above my garage and the other walls don't lend themselves too well to a gas furnace vent. I know gas is better and cheaper but I am looking for heating to take the edge off in the winter - not to be able to work in a t-shirt out there.
AndrewT
I ended up getting two Qmark PH-5HW electric heater units based on research I did here. I cannot easily get a gas heater installed as my MBR is above my garage and the other walls don't lend themselves too well to a gas furnace vent. I know gas is better and cheaper but I am looking for heating to take the edge off in the winter - not to be able to work in a t-shirt out there.
AndrewT
Last edited:
Just to amplify what Rickairmedic indicated, there are several reasons connecting a garage to household central HVAC are against code and common sense:
- Return trunks are DEFINITELY a no-no as it'll **** chemical fumes, CO, etc back into the living space. Supplies to sealed spaces with no return will result in an inefficient system - either the supply reaches a stall pressure or you're blowing conditioned air out of any cracks/crevices in the garage insulation barrier - that could mean back into your house too.
- Chemical fumes/vapors and CO have a direct path into the home via supply trunks when HVAC is not running. Many of these chemicals are flammable in gas form. If they reach your pilot light/furnace or other ignition source - boom!
- Fire barrier is breached by the supply trunk - this can be remedied by a barrier rated damper
Many have done it and lived but there is a reason why its against code in most areas. There is also a reason why most insurance companies have "issues" with these arrangements.
- Return trunks are DEFINITELY a no-no as it'll **** chemical fumes, CO, etc back into the living space. Supplies to sealed spaces with no return will result in an inefficient system - either the supply reaches a stall pressure or you're blowing conditioned air out of any cracks/crevices in the garage insulation barrier - that could mean back into your house too.
- Chemical fumes/vapors and CO have a direct path into the home via supply trunks when HVAC is not running. Many of these chemicals are flammable in gas form. If they reach your pilot light/furnace or other ignition source - boom!
- Fire barrier is breached by the supply trunk - this can be remedied by a barrier rated damper
Many have done it and lived but there is a reason why its against code in most areas. There is also a reason why most insurance companies have "issues" with these arrangements.
The above makes sense. I ended up not going this route anyway. But surprised that 2 different HVAC guys all suggested this - and they knew the work being done was going to have permits and inspections that they would sponsor.
Note the work did NOT include return lines. It was obvious to even me that this would be an issue. But just included putting an additional supply line or two into the garage.
AndrewT
Note the work did NOT include return lines. It was obvious to even me that this would be an issue. But just included putting an additional supply line or two into the garage.
AndrewT
rickairmedic
Well-known member
Andrew not sure what part of the country your in but I know down here where I am it has been a LOUSY winter for Buisiness so I can see 2 guys offering to do things a little out of the norm just to try and get the bid . Also most inspectors are looking at 3 things the Flue pipe ,the gas line , and the filter location beyond that they dont look at much before slapping a sticker on for you especially if you are known for quality work.
Rick
Rick
I live in NJ. The one written estimate states:
"Add Heat Zone off of existing system using a zone control and separate t-stat".
The other estimate used similar wording. Both included permits/inspections. I am glad I did not go this route if its not safe.
AndrewT
"Add Heat Zone off of existing system using a zone control and separate t-stat".
The other estimate used similar wording. Both included permits/inspections. I am glad I did not go this route if its not safe.
AndrewT
Andrew - your quote may have a bit more merit as it sounds like the contractor is somehow isolating the garage into a separate zone. I have an idea how this might be done but perhaps your quote has more info or rickairmedic has input too.
Sounds like this is a bit more sophisticated than the usual "hack into the house HVAC to get heat in the garage" routine.
Sounds like this is a bit more sophisticated than the usual "hack into the house HVAC to get heat in the garage" routine.
Thats all that was written on the quote - other than the large price. My understanding was that he would put a t-stat controlled dampner/baffle on both sides (or one side?) of the supply line he planned on routing into the garage from the main home heating duct supply. In normal mode, the air flows through the system for just the house and the duct supplying the garage is closed. In supplemental mode, when the garage t-stat tells the furnace to kick on, the dampener opens and heated air flows through the new duct into the garage - shutting off once the temp hits spec.
He said its like adding a third zone to an existing 2-zone system that I currently have for my 2 story house (1 zone per floor).
AndrewT
He said its like adding a third zone to an existing 2-zone system that I currently have for my 2 story house (1 zone per floor).
AndrewT
truckman5000
Well-known member
- Joined
- Mar 11, 2008
- Messages
- 1,440
ya not a bright idea, im a lic. plumber, heating guy, for a garadge thats used for screwing off in, it would be ok, but also, your home is say 1,200sq' your heating systems designed for that sq', alot of towns/states require a heat loss and sutch when installing a system on a new home, so the system is probely sized for the house. to run properly, if you add say 600sq' by garadge your furnace is now working nearly 2-3x harder (how btu x space works out), because of btu out put and the added space..ur heating bills would be alot more than they are now. ie, system running alot more than it should.
also like said correctly yould need return air from the added zone, any paint, fumes ect would be now in your house, which isnt good haha.
it would be cheeper to have a plumber run a gas line into the garadge and install a gas fired reznor heater, or modine hot dowg.
because the garadge you want to be warm when you have a project, not all the time...in most cases, the added BTU with the secondary heat source, ie reznor heater, you can turn it on and in a few mins, the garadge is warm.
also stay away from the vent free heaters in garages, they take the air from the room to create heat, witch can mean contaminated air if your painting and such
also like said correctly yould need return air from the added zone, any paint, fumes ect would be now in your house, which isnt good haha.
it would be cheeper to have a plumber run a gas line into the garadge and install a gas fired reznor heater, or modine hot dowg.
because the garadge you want to be warm when you have a project, not all the time...in most cases, the added BTU with the secondary heat source, ie reznor heater, you can turn it on and in a few mins, the garadge is warm.
also stay away from the vent free heaters in garages, they take the air from the room to create heat, witch can mean contaminated air if your painting and such
Well, with a properly zoned system the safety risks are generally minimized. However, you have to make sure that the damper is located at a high end in the supply line (i.e. not all the way down near the air handler in the main supply trunk. Reason being, vapors/chemicals can migrate all the way back to the damper and if they're heavier than air (many are), you could have a safety issue.
However, having said that, there is still the operating efficiency issue. Without a return, you're still going to push conditioned air out of the garage (and hopefully not back into the house) or stall the air handler if the garage is tight. And unless, the unit is oversized as it is, it may not be up to the task of providing the additional BTUs required by the garage. Also, the way I see it with 3 zones, you could end up with a furnace/airhandler running nearly 24/7 depending on the zone demands - not a killer but will result in more frequent maintenance/repair/replacement cycles.
I'd definitely investigate another heating option. A radiant or separate heater for the garage is much easier to use "on-demand" and having it completely independent of the home furnace adds to the safety aspect. If none fits the bill, than the additional zone may be worth further exploration.
However, having said that, there is still the operating efficiency issue. Without a return, you're still going to push conditioned air out of the garage (and hopefully not back into the house) or stall the air handler if the garage is tight. And unless, the unit is oversized as it is, it may not be up to the task of providing the additional BTUs required by the garage. Also, the way I see it with 3 zones, you could end up with a furnace/airhandler running nearly 24/7 depending on the zone demands - not a killer but will result in more frequent maintenance/repair/replacement cycles.
I'd definitely investigate another heating option. A radiant or separate heater for the garage is much easier to use "on-demand" and having it completely independent of the home furnace adds to the safety aspect. If none fits the bill, than the additional zone may be worth further exploration.
sneezer41
Well-known member
No no no no no
If you blow air out of the house it MUST be replaced. Where will it come from? It will come from one of two places, both bad. One is the garage, carrying possible exhaust fumes with it. The other is the outside world, carrying unconditioned air with it, wasting all of your heat.
Don't do it. Just because someone will issue a permit does not make it right
If you blow air out of the house it MUST be replaced. Where will it come from? It will come from one of two places, both bad. One is the garage, carrying possible exhaust fumes with it. The other is the outside world, carrying unconditioned air with it, wasting all of your heat.
Don't do it. Just because someone will issue a permit does not make it right
sneezer41
Well-known member
if you have hydronic heat that works just fine
6768rogues
Banned
In NYS, which uses a similar code to most other states, it is not code compliant to mix garage air with house air through a heating or cooling system. Supply only will not be balanced, the house will be under negative pressure and the garage under positive pressure, so which way do you think air will try to migrate? Also, there is a wall constructed to separate a garage fire from the house for a period of time. A duct penetrating the wall will spoil that fire separation.
Trying not to beat a dead horse but summing up the remainder of the comments, I think its easiest to say that it can be done. However to make the system safe, you need a properly installed fire rated damper installed in the correct location and zoned control for the garage. To make the system efficient, you'll need to provide conditioned make up air for the house and and conditioned "exhaust" air for the garage - read heat exchangers for both. Once you add all this up for cost and insulation, I think you'll find many other viable alternatives that are much better suited AND cost substantially less.
Sure short cuts can be made, but you'll compromise safety and/or efficiency.
Sure short cuts can be made, but you'll compromise safety and/or efficiency.