Condenser Pad--Concrete or Pre-fab?

[Angelfire]

Hiya Folks,
Ordering up a mini-split system for the garage today. Now that I've figured out what I want, I'm turning my attention to the install and such. I was always under the impression I'd just pour a concrete pad until I started seeing the pre-fab units (some are plastic, some are light weight concrete, some are Styrofoam with a concrete over them, etc....) and it's got me wondering if these pre-fab things might be a better way to go? It's getting colder here now and I really don't like pouring concrete anyway, haha. Anyone using the prefab ones and if so, what do you think of them?

Cheers.

 

[Falcon67]

Our house unit sits on a pre-fab pad. No problems so far, puts up with being clipped with the weedeater.

 

[Angelfire]

Thanks Chris. I'm guessing you may not get much freeze/thaw to cause heaving? That's my biggest worry I suppose....
Cheers.

 

[rlitman]

I have two mini-splits. One condenser sits on a masonry wall, but the other sits on a pair of 18x18 patio tiles. Frost heaving isn't going to make it flip over. I don't see an issue with a pre-fab pad.

 

[brewchief]

We set 50 plus A/C units on plastic pads every summer, very few issues with frost heave, if it does move slightly you just stick a shovel under one side and lift it up and shove some sand under it.

 

[zmaxmotorsports]

I've used hundreds of plastic condenser pads,never had a problem with them.just make sure to put a good/level rock base under it like any other pad.

 

[DC73]

. . . some are Styrofoam with concrete over them, . . .

I went this route for my shop unit. Was going to pour my own but ran into a builder friend and he mentioned he buys these in bulk and sold me one for $35. Couldn't beat that. I put some sand down to aid with leveling and was good to go. No issues so far.

DC

 

[thammel]

I'm an old school fanatic. I always pour my own pad and go deep with a builders tube in the middle down 3 feet. I use rebar and tie it into the pad. Lots of concrete. These pads never go out of level. One of my pet peeves is all the hvac units that aren't level. Let's see - 3 in prior houses and 5 in this house...so I've done 8 of these. Current house - 2 main heat pumps for the house, backup generator and 2 mini splits for the garage.

Tom

 

[bikesandcars]

Plastic pre fab worked well for me. Level the area with a little tamped stone and plop it down

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[finn]

I poured my first one, but have installed the plastic prefab units in two subsequent homes.

The prefabricated pads are cheap and simple, and do the job.

Pouring the first slab was sort of **** retentive, in retrospect, and a waste of time and effort on my part.

Nobody is going to pay $.05 more for your house at resale time because it has a poured slab.

 

[Angelfire]

Thank you folks for all the inputs. It appears these prefab pads do seem to work ok. We don't experience a ton of frost heave here where I'm installing it as we're pretty much built up on sand anyway but thought I'd ask. Appreciate the inputs....
Cheers.

 

[Falcon67]

Thanks Chris. I'm guessing you may not get much freeze/thaw to cause heaving? That's my biggest worry I suppose....
Cheers.

Good point, no we don't. I had a concrete pad under the condenser unit at the old house and it was a bit of a pain to level. I'd think a composite would give a little with heave, but then composites might get brittle at cold temps too. Wonder how a 6" gravel pit with a floating slab would react to extended cold.

NM should not be that different than Texas panhandle unless you're up in the mountains.

http://www.practicalmachinist.com/vb/general/ot-pads-vs-slabs-ac-units-143209/

http://www.finehomebuilding.com/1996/11/01/frost-heaves-in-concrete

 

[bikesandcars]

Who cares as long as the unit doesn't fall over. No resale or functional benefit to pouring anything.

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[Gerald O]

Poured in place concrete. With masonry standoffs and anchor bolts.

Every plastic prefab 'mounted' unit I've seen settles after a few years and is sitting cockeyed. Looks redneck and puts stress on the lines.

 

[Jackfre]

I would suggest that you skip the pad and use a wall bracket. Airtec and Diversetech (the same people who make the pads) offer the brackets. In my experience the units stay cleaner and fewer critters get to them. Snakes do like to work their way up into the electronics, which blows everything including the snake. If you get much freezing weather in NM, the thing you are trying to avoid in winter operation is icing up the base of the condensing unit in the defrost cycle. Putting the unit right on a pad can cause the moisture melting off to freeze from the pad up into the unit and in extreme situations can damage the unit. If you go with a pad make sure you at least elevate the unit off the pad. The Friedrich unit shown is good example. Also, for low temp climates, some manuf/models have base pan heaters installed. Some offer them as options. Eyes open!

 

[Angelfire]

Thanks Jack. I may just go that route. Was looking to avoid that as I was trying to isolate any vibrations from entering the walls but it might just be the way to go. We don't get much snow here but we've had some winters where the nightly temps are just above 0 for a few days in a row...hardly arctic I know. But your comments regarding the critters makes a lot of sense....we've got plenty of them. Appreciate the input.
Cheers.