Anchoring mini-split condenser to a slab

[Sukhoi]

I'm installing a 24K BTU / 2 ton mini-split in my garage primarily to use the A/C when working out on the hottest days. So, it won't be used that much; probably a couple dozen hours a year. I am unfamiliar with how much the condensers vibrate. Is it really necessary to drill into the slab next to my garage to anchor the condenser? I'm tempted to use these rubber pads and see if they do a good enough job keeping it in place. Is that a reasonable idea or is the condenser probably going to vibrate itself all over without being anchored?

 

[herm0016]

you should bolt it down. wedge anchors would be fine and i would use something similar to those pads under it. keeps it up with some airflow under the unit, dampens vibration and noise. all good things.

 

[Greenman]

I believe being anchored is a code requirement. It's about the unit getting bumped rather than vibration movement. It's a pretty simple process to install a wedge anchor. A quarter inch tapcon would do the job as well.
If you really don't want to drill a hole in the slab, use the rubber mounts and put a blob of epoxy under them.

 

[skyking]

I used 1/4 wedge anchors plus a rubber block.

 

[Sukhoi]

Thanks, I'll get those pads and anchor it all down. Might do the epoxy too instead of wedge anchor - that's a good idea.

 

[iRONic]

Are you in an area that gets any measurable amount of snow? When I lived in Connecticut we had mounted ours to the outside wall, cause we tended to get 18 to 30 inches of snow each year.

Edit: Added a pic

 

[Ajay]

Ours is just anchored at ground level to a 70ish pound slab (New Hampshire). My bro got one a couple of years ago and they mounted his up about 2.5 feet above ground on a metal structure. We haven't had a problem in 11 years (was surprised the installer didn't recommend a cover).

 

[Sukhoi]

Are you in an area that gets any measurable amount of snow? When I lived in Connecticut we had mounted ours to the outside wall, cause we tended to get 18 to 30 inches of snow each year.

Edit: Added a pic
View attachment 61347

Heh no, the world would stop functioning if we got any snow here. The condenser is going to be under the eave on the rain shadow side of the house, so it'll get far more water exposure from me rinsing it down once a year than from rain.

 

[Paperdoc]

A proper mounting pad is essential for an A/C compressor unit. That MAY be an existing concrete pad if you have the right space, and IF it is completely level. All units need a certain amount of free space around them, and must be kept level both for compressor functions and for lifetime of the fan unit inside.

Take a look at this web page for some info.

Guide to AC Condenser Pads | ClimateCare

For an air conditioning unit to function properly, it requires the installation of specific components. The AC condenser pad is the most integral and this article will tell you why.

www.climatecare.com

As you see, there are alternatives to a new custom concrete pad - the page does not address using space on an existing pad. But also consider the synthetic pads commonly used for smaller units like the one you are considering. You may be able to use that on top of your concrete, with either small anchors or epoxy glue to fix it in place. Check with suppliers for how well this might work for you. I'm having a new central air system installed for our house - 2T (24,000 BTU/hr), we're not in a really hot climate - this week and they said they will use a synthetic pad installed directly on carefully levelled ground (already packed by age) next to the house.

 

[Sukhoi]

I unfortunately can't use one of the synthetic pads because it's near a door and would be a trip hazard. I'm just going to put a couple drop-in anchors in the slab, mount the condenser to those, and use nuts on the threaded rods to level it.