PREFABRICATED CONCRETE SLABS

[Bocatrip]

I have done it a little over 24hours after but I obviously prefer to let it cure fully. A lot depends on the concrete used, conditions, and the customer or homeowner.

I usually build the frame for it out of 2x10s and if it is a must get the system up and running that day I run a few boards across the top of the box, just above the concrete and install it hovering an inch above, come out a few days later and move and secure everything. Not ideal but when given the choice of a pad thats agonna be bad or having some ugly lumber in the homeowners yard for a couple of days I like to walk away from the job knowing I don't have to worry about it failing.

If you can possibly wait for the pad to fully or mostly cure before you go slapping the condenser on there that is what I would do.

How many days are we talking about? 2? 7? I think my installer was talking about that setup of having it hovering over the pad. I just didn't confirm with him that he would come out 3 times just to allow me to install the pad.

[forcryinoutloud]

Yea I usually try to schedule those for the fall or spring so I don't have to hear from the woman of the household how it is 74 inside and she can not live unless it is 76.

What is this Fall and Spring that you speak of?

[forcryinoutloud]

How many days are we talking about? 2? 7? I think my installer was talking about that setup of having it hovering over the pad. I just didn't confirm with him that he would come out 3 times just to allow me to install the pad.

If it is at all possible we like to set the condenser a couple feet away from the existing location so that the slab can be poured and allowed to cure for at least 48 hours. When that is not possible we have set the unit after 24 hours or so and anchored it down on a follow up visit before the inspection.

We will get our Hurricane Clips attached to the unit so that all that needs to be done later is drill 4 holes and drive in some Tapcons.

As I mentioned earlier, most customers don't want to wait and like us to use the pre-fabbed pads.

[JeffeVerde]

This is all very interesting to read. I recently had three different vendors quote a system R&R, and two of them told me that I need a plastic base for the condensor instead of the current concrete pad because "the condensor is beating itself up, attached to that hard concrete pad".

[Bocatrip]

This is all very interesting to read. I recently had three different vendors quote a system R&R, and two of them told me that I need a plastic base for the condensor instead of the current concrete pad because "the condensor is beating itself up, attached to that hard concrete pad".

I've never heard that one before. Poured concrete is really the way to go, but if it is not practical, I'm sure the lightweight pads will do what they are intended to do. I'm just not sure how long they can last. I will at this point most probably be going the lightweight pad route as getting a subcontractor in addition to my a/c installer to coordinate in a reliable fashion does not look like it is in the cards.

[lions_lair]

Were not allowed to use pre fab concrete pads here. Plastic only.

[bwalley]

The lightweight pads are code approved a pourde pad would be better, but not necessaary.

the pads are tested in accordance with FBC, the plastic pads are not code approved.

If you are going to pour a pad, just use fast setting high strength (5000 PSI) concrete, you will be able to set the condenser in 4 hours, just use a 2x4 on edge as your form and stake it securely, use the 3 4 5 method to make sure it is square.

It isn't feasible to bring a truck out for such a small pour, and if you do, then you have the poroblem of where o put the wash out from the truck.

[bwalley]

I have done it a little over 24hours after but I obviously prefer to let it cure fully. A lot depends on the concrete used, conditions, and the customer or homeowner.

I usually build the frame for it out of 2x10s and if it is a must get the system up and running that day I run a few boards across the top of the box, just above the concrete and install it hovering an inch above, come out a few days later and move and secure everything. Not ideal but when given the choice of a pad thats agonna be bad or having some ugly lumber in the homeowners yard for a couple of days I like to walk away from the job knowing I don't have to worry about it failing.

If you can possibly wait for the pad to fully or mostly cure before you go slapping the condenser on there that is what I would do.

Concrete never really fully cures, as long as it is hydrated it keeps curing.

We have poured footers one day and layed block the next day and that is with standard 3000 psi pump mix

use fast setting high strength concrete mix, wait 4 hours and set the condensing unit.

[davidhamel]

Here in Palm Beach County Florida, A/C contracters use the prefab concrete slabs in lieu of poured concrete. Most customers are not even aware of these slabs not being the "real deal" and being quite cheap and flimsy. I believe it's a combination of concrete and fiberglass and is fairly light (compared to solid concrete). I'm concerned that if the wind picked up enough in a very strong storm/hurricane, away goes the condenser and slab together. I have a 3 ton Trane XR15. Of course at that point, my roof might go the same route! Although hurricane straps are required in numerous Florida Counties, the slab itself is not very substantial. I know poured concrete is the way to go, but it will be a pain at this point to have it done. What do you guys think about the prefab? Does it do what it is intended to do to hold the condenser in place and structurally, should it last 10 years+?

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[Special Ed]

Okay, let's get real here....

If the winds are strong enough to actually blow over a condenser screwed to a concrete pad and attached to be house w/copper tubing then you have bigger problems to deal with, and you should probably have already evacuated to a safer location.

In other words, you're making a mountain out of a molehill.

[beenthere]

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