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How to keep garage comfortable as a workshop in 5A

orange_cat | Posted in General Questions on

We are finalizing the HVAC for the house and advice so far was to keep garage off the HVAC system and have an independent minor source of heat and cooling.

I would love to hear your views.
The garage is 21 by 16 slab on grade 7 feet height. Has a single extra insulated door and the insulation otherwise is the same as the rest of the house (R10 floor, R32-38 walls and ceiling). Faces north and has outside exposed walls on 3 sides (one 21 foot wall meets the house). Above the garage is the rest of the house, garage is at grade, there is one connecting door to the rest of the house and there is a sink too along the wall that has a mechanical room on the other side of the wall. (SO cannot have garage too cold).

My husband has woodworking tools (which create dust and the finishes like teak oil that stink) and would like to use the workshop year round but there may be weeks when the woodshop is not being used. (It is a long-standing hobby, so he works on a project as he has time – so a new bed for the kids, that sort of things, slowly). The garage door will be closed always (faces somewhat busy street with pedestrian traffic – near school) except when in use (there is parking in the front, so the car does not need to be in the garage much as a I prefer it to be). There is an operable casement window at the back of the garage, but realistically some heating and cooling would be needed. 
We were originally thinking some sort of standalone oil-filled radiator but then cooling came up, so ok – standalone AC? But what about dust? 

What do people generally advise for situations like this? We are about to start laying out hvac elsewhere in the house right now (heated floor and centrally ducted AC), so it is not too late yet to add the garage, but we would not want it to be heated beyond 65F and cooled below 76 F.

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  1. Expert Member
    Akos | | #1

    I use an oversized budget wall mount mini split. Make sure the unit has a base pan heater as this is needed in our climate.

    With dust it becomes more complicated. Heat would be easy since you can tie it into the house floor heat. If you want cooling, that means something with a decent filter.

    You could go with something like this that would do both heat and cooling with their FBL1-2 filter box:

    This could be left exposed and simply mounted to the ceiling without any ducting.

    You also can't go wrong with a simple shop heater. Either electric or gas, they are generally the cheapest source of heat for a place that is only used occasionally.

  2. walta100 | | #2

    I think a PTAC heat pump would be a good solution for a workshop if you must have AC and plan on keeping the space heated.

    PTAC (Package Terminal Air Conditioner) are often found in Motel rooms under the front window.

    When the PTAC gets dirty from the saw dust you can slide it out and put it in the driveway and turn the hose on it out and put it back in the wall.

    Is it necessary the heat the space 24-7? Could you use weatherproof hose bibs for the water supply and put the trap inside the heated wall.

    If the shop only need heat I like the idea of an oversized unit that will quickly heat in just a few minutes.


  3. canada_deck | | #3

    My two cents:
    1) Set up the plumbing so that it's easy to shut off that sink from the other side of the wall if you are ever worried about the space becoming freezing. No sense keeping that entire space heated for the coldest weeks of the winter just because of one tap (unless you are also storing things in there that you need to keep above freezing such as certain paints.) That said, I'm guessing it will often stay above freezing without any additional heat just just from heat through the ceiling, wall, and floor.

    2) For a garage that is only occasionally used, the trick is to have a way to warm it up quickly. Agree with comments above that it seems like a good application for a shop heater with a fan (
    ). There are some risks with dust but that is probably manageable with a bit of care and common sense (e.g. don't let it get filled with dust during the summer without cleaning it and then have it kick-on for the first time unsupervised in the winter, don't use it at the same time you are making a lot of dust.) I think the only foolproof solutions for dust would be in-floor heating or explosion proof heaters. Lower temperature options such as a hot water radiator or a wall mounted lower temperature panel heater may also be appropriate.

    3) Your insurance provider may want you to have a fixed hard-wired source of heat (e.g. not a portable plug-in space heater) and I'd agree that's generally a good idea. You might consider a small fixed hard-wired source of heat to keep the space above freezing (e.g. perhaps a wall mounted panel heater) and then a large portable shop heater to quickly warm up the room when you want to work. This is an example of a wall mounted panel heater that can be hard-wired:

    4) You may not be allowed to extend your house AC system into your garage for safety reasons (e.g. risk of vehicle fumes entering duct work, fire safety, etc.) The garage may need to be completely sealed off from the rest of the house.

    5) I'd also install an exhaust fan in the garage (It could be a wall mounted fan to the outside.) If you are doing work with fumes in the garage (like staining), you will want to be confident you have negative pressure in that space.

    6) Are you sure you need cooling? I'd probably rough in the wiring and maybe even a conduit for the piping to be able to install a mini-split heat pump and would wait a year or two to see if that is an actual need.

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