piping central A/C into attached garage?

[hell_fish_65]

My home is about 1600 sq ft and the attached garage is about 200. Yes, very small. I want to put central A/C to the garage. What size unit will I need to accomodate this space? Hopefully I can just plumb in a new vent or 2.

 

[Ray-CA]

It is not recommended to tie the home and garage systems together. Think about all the chemical odors in the garage. Fuel, exhaust, cleaners, solvents, paint etc. Now imagine those same odors wafting through the entire home. In an extreme case, solvent fumes in the house, stove lights.......BOOM.

With only a 200-sqft garage, I'd hang a room a/c unit and heat with a propane/ng/electric style hang from the rafter style heater.

Ray

 

[mmg440]

I would think a window unit or a split a/c unit would be a good solution. I would also NOT recommend running ducts from the house to the garage.

If the garage is not yet insulated I would recommend doing that first.

 

[hell_fish_65]

Garage is insulated in the attic and walls. Its more of a family play room now than a garage. All the chemicals are in the shop. I have a window unit which is ok for the summer, but no heat during the winter.

 

[Ray-CA]

If it's not going to be used as a shop, then there is probably no reason that you could not connect it to the HVAC system from the main house. I thought from your original post that you wanted to connect from the house into a working shop/garage.

Ray

 

[hell_fish_65]

Understandable. Sorry for the confusion. How large a compressor should my house have to justify to added space?

 

[Torque1st]

Does your present AC cycle off and on at any time during the hottest days? If it does then you probably have enough existing capacity to cool the small added area. In the worst case when you add that area your AC may run steadily on those very hot days and even lose a degree or two during the day which you won't even notice.

 

[rickairmedic]

1600-1800 SF would need a 2 1/2 to 3 ton system depending on insulation levels the general rule of thumb is 500 - 750 SF to a ton . I will tell you it is against code to tie your HVAC system into a garage that being said if you are not actually using it as a garage then I dont see a problem . I will recomend though that you make it easily removable so that if you ever decide to sell the house you can undo it . Either that or go ahead and remove the garage door and put up a wall with french doors where it was and then it will be more like a rec room and not a garage.

Rick

 

[larry4406]

I agree with rickairmedic. When I was building residential houses, we would utilize the garage of our models as the sales center. Granted we had a permit for it, but the garage was connected to the house heating and cooling system and the garage doors replaced with french doors. In general, we would cut a register into the band board area and run ductwork to the basement unit. In many cases we would put base display cabinets along a back wall and run a round duct through it so as to get a heat register on the opposite side of the former garage. We would also take the access door to the garage from the home off its hinge; this opening would then act as the return. We did this with 2 car garages and some larger 3 car garages and it worked well; we never utilized a separate mini-split for the garage conversion. Ultimately, when the model was sold we had to tear it all out and convert it back to a normal unconditioned space with no tie to the house heating systems per Code and have it inspected.

 

[Tom2]

My house was built with the air ducts tied into the garage, as are many older homes. Its fine, as long as you don't have a cold air return in your garage, that would be stupid. Otherwise, fumes are not going to be circulating around.. Since yours is living space, then do whatever you want (unless you plan to sell soon).

The main concern is probably whether or not your HVAC system can handle the extra sq/ft load. But I imagine you can just keep the register closed at most times.

 

[rsanter]

if you do tie the grage to a home AC duct. I would also install a (not sure what it is called) diverter valve/butterfly valve thing in the AC duct to the garage so you have the option to turn it on and off as needed

bob

 

[AKS_Racing]

Not to take anything from the OP, but I have a detached garage that has a large upstairs living space and I want to install HVAC. It also has two rooms downstaisr, and my hope was to have a butterfly dampner that could open to supply HVAC to the grage area as well. Based on the comments above, it seems that this may not meet code. Is this the case, even if the grage HVAC does does not tie into the existing HVAC systems already in the house?

I really would like to have HVAC in the garage area for those very hot and very cold days. Thanks in advance for any direction provided.

 

[gesoffen]

My house was built with the air ducts tied into the garage, as are many older homes. Its fine, as long as you don't have a cold air return in your garage, that would be stupid. Otherwise, fumes are not going to be circulating around.. Since yours is living space, then do whatever you want (unless you plan to sell soon).

The main concern is probably whether or not your HVAC system can handle the extra sq/ft load. But I imagine you can just keep the register closed at most times.

In general, it is NOT a good idea to tie the homes HVAC system into a garage (as mentioned before - fumes, CO, CO2, chemicals, and explosive vapors). However, with proper precautions, it can be done. Two of the most important things regarding safety are 1) Absolutely no air return connected to the house and 2) an active fire damper installed in the supply trunk leading to the garage/shop.

Beyond that, there are plenty of other rules of thumb to follow to increase safety and efficiency - air supplies up high to avoid heavier than air vapors from making there way into the supply ducts and potentially into the house, insulated walls, ceilings and doors, etc.

 

[Tom2]

In general, it is NOT a good idea to tie the homes HVAC system into a garage (as mentioned before - fumes, CO, CO2, chemicals, and explosive vapors). However, with proper precautions, it can be done. Two of the most important things regarding safety are 1) Absolutely no air return connected to the house and 2) an active fire damper installed in the supply trunk leading to the garage/shop.

Beyond that, there are plenty of other rules of thumb to follow to increase safety and efficiency - air supplies up high to avoid heavier than air vapors from making there way into the supply ducts and potentially into the house, insulated walls, ceilings and doors, etc.

Yea..I totally understand what you're saying.. And I imagine homes aren't built that way any longer (for good reason -- mine is from early 70s).

I will say that Ive never smelled anything from the garage in my house. So I have zero interest in changing the system. I love it.

The garage is below the living room (split level ranch). I hate the design...but it works.