Mini Split Condenser in Garage? With ventilation?

Question

I live in a fairly warm and dry environment and due to HOA restrictions am unable to place a window A/C unit, outdoor unit, or a system on the roof. I understand that A/C shouldn't go in attics due to the heat.

However, I was wondering if an A/C unit could go into a garage that had an exhaust / intake fan cut into the side of the wall. This air flow could even be directed into a self contained box which the condenser portion is in.

Is such an installation feasible? If so, how do I calculate what amount of CFMs the fans will need to push to sufficiently cool the a/c unit?

Is it correct that a 1 ton A/C system passes about 400CFM per minute? If my garage is 5000 Cubic feet (25x25x8), then it would take about 12minutes to cycle through all the air. Thus I would need exhaust and intake fans that can push 400CFM?

Thanks.

Answer 1

According to this webpage, "the answer is an emphatic NO." The page goes on to say this is because the total volume of air in an enclosed space is insufficient, including a garage with an open door as the air isn't likely to circulate enough.

From this we can deduce:

• There is nothing in most codes preventing you from doing it.
• If you are planning to do this, you'll need to pay very close attention to where your intake and exhaust air are coming from.
• If you don't design your ventilation perfectly, your system may not be able to cool your space

Answer 2

I did it 10 years ago and it has worked well. It is only a room size unit but will work with larger sizes. It is not visible from outside except the 1/4" plastic drain hose sticking out of the garage wall. It is mounted close to the ceiling. I made a plenum with a 1/4 " fiberboard with a white plastic finish , so from in the garage you see a white box near the ceiling . The condenser draws air from in the garage, blows through the coils into the garage attic and eave. In the living space there is a normal room AC unit face ( projects from the wall about an inch.) except it is mounted a few inches below the ceiling. It is a window unit , essentially the 2 X 4 stud wall is the "window", I added no extra brackets. It has a remote control so being so high is no problem; actually gives excellent circulation . The only problem is that I forget to clean the air filters.

Answer 3

I would say it would be simple if allowed to install 2 louvered vents on the outside of the home in the garrage wall. Encase the system in a box with the vents use a powered fan either temp controlled or if the unit has an aux contact on the motor contactor that can turn on the fan on. This would work you just need to move the air so the unit can heat or cool.

Answer 4

If you are anticipating making an opening in the wall of the garage so that the hot exhaust from the condensing unit would have an unobstructed path to the outside, then in theory your idea to have the condensing unit inside the garage could work.

You would need some sort of seal to prevent hot air from the condensing unit from flowing back into the garage. You could mount the condensing unit on brackets on the wall of the garage. The opening could have a decorative grill on it that would hide the fan.

Normally the fan side of the condensing unit faces outward from an exterior wall so this might not work in practice because having that face of the condensing unit close to the inside of the wall of the garage might impede access to diagnostic ports of the unit.

The input air to the condensing unit would be from the inside the garage and there would have to have an opening for air to be admitted to the garage to replace that being pumped out.

You would still have to get permission from the HOA board to do this and they might find grounds to withhold approval. Would the HOA allow you to cut an opening in the wall of the garage?

Finally, the noise of the condensing unit would be trapped in the garage and could be very disturbing. The condensing unit is meant to be outside where the sound disperses. But modern condensing units make much less noise than formerly.

*EDIT** You could get creative with ducting to get the hot air to the outside of the garage. The opening on the outside might be a rectangle 6 ft long by 0.5 ft high on the wall where it would not blow on passersby.