My garage is heated but it's attic is not. The attic is accessible and could make a good location for a large air compressor - saves space & could muffle the noise. But the annual temperature swings in the attic are a concern.

  • Winter temps here can go down, at the extreme, to < -10 F (-23 C).

  • Summer highs might be less of a concern, but get into the 80s/90s (26/32) outside - probably > 100 F (37 C) in the attic.

Aside from whether extreme temps could be harmful to the motor or compressor pump itself, the tank is bound to get some condensation in it. I would plan to have a drain tube / valve plumbed in, but I wonder if frozen ice inside the compressor tank could cause an issue?

I checked a manufacturer's manual for a somewhat expensive compressor and it literally says nothing about operating temperature.

Reading around internet forums I get kind of a mixed impression - nothing that seems conclusive.

There are indeed some compressors used outside all the time - like at gas stations for filling tires. But those might have been purpose built for the conditions so I don't infer much about a standard workshop compressor from that.

  • The summer heat will be bad for the life of the compressor/motor, and also for the amount of water in the air (the amount that will not come out as condensate, as the tank will be so hot between being in a hot attic and attached to a poorly cooled compressor in a hot attic.) That's also one heck of a load on a part of the garage that is rarely built for anything more than light storage, if even that.
    – Ecnerwal
    Commented Apr 25, 2020 at 0:07
  • @Ecnerwal the attic has a portion that was finished; even though the rest is not I think it was built for occupancy loads throughout. Regardless the weight will certainly be spread across several trusses, I think the lbs/sqft will be acceptable even though I know its closer to a point load on them individually. Commented Apr 25, 2020 at 1:40

2 Answers 2


Ice in the tank is not going to cause a problem. The issue is using the air in sub-freezing temps. Ice can form in the hose or in the tool. A good solution is to install a water separator that will catch the water before it goes into the hose and freezes.


This Practical Machinist forum post by Lakeside53 says the following:

Look in the Quincy manual (you can get it online). The oil you use depends of the temperature. If your compressor is "inside" and/or not subject to freezing, Quincy recommends 30 SAE (ISO 100) non-detergent hydraulic oil. Outside low temperatures -down as low as 10 SAE.

I need to see if I can find the original source for this. But it implies that many compressor heads at least will operate just fine in the cold assuming they are properly setup.

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