AC pad not level

[Overland1]

My house is about seven years old now and little by little the pad that the heat pump rests on has been sinking on the side closest to the house. The pad is a heavy gauge plastic or fiber material that the heating and cooling company furnished. I have two units but only the larger of the two are settling. I'm sure it is settling on the side next to the house because a small amount of back fill had to be added next to the foundation.

My question is, has anyone tried to re-level one of these? I am concerned about how much it can slope before having a detrimental effect on my heat pump.

[Splinter Puller]

take a few 2x4's and rig up a carry system so you can suspend the unit up a bit... pull the pad.... add pea rock to level.... replace the pad and drop down the unit.

or... Do what I did and pour a new concrete pad all while the AC condensing unit was suspended overhead for a few days.  This was done while it was not running of course.  I had covered the unit in plastic to keep cement from being slopped on it.

[daddo]

It usually sinks where the roof drips rain or the downhill side of a tilted ground.. If that is the case, you can install a gutter to direct the water to the sides.

I use the truck dolly to lift the sunk side of the slab and fill it in from there. Mind the copper as not to kink it.

It was said by GE decades ago- no more than 5 degrees tilt. Further tilt is not good for the compressors internal spring mounts.

[Overland1]

I had gutters installed when I built the house. I like the idea of the truck dolly.

[Snipe Hunter]

It usually sinks where the roof drips rain or the downhill side of a tilted ground..

This is exactly what I see when inspecting homes. One neighborhood had all the homes built on a slope and all the condensers were leaning down that slope. I saw a couple houses that had little pressure treated retaining walls built on the downhill side. Maybe 8 inches above grade? I spoke with one of the home owners and he said he built the retaining wall and then used it as the fulcrum and used 8ft 2x4s to pry up one side of the condenser pad as he stuffed gravel under the pad. It looked great.

[toolmiser]

If you can raise it and hold it for a while, You can used spray foam to fill the void.  I did that with a section of sidewalk a couple years ago.   It's holding fine.

[fredhargis]

If you can raise it and hold it for a while, You can used spray foam to fill the void.  I did that with a section of sidewalk a couple years ago.   It's holding fine.

Actually not a bad idea (I think). There's a local company offering to re-level sidewalks, basement sections and so on using just that method. They drill holes in the slab and pump the foam in, it actually lifts the concrete. I'm not sure if it's the same foam formula that comes in a can, but they guarantee their work for some very long length of time.

[JosephP]

Interesting.  There is some research that has found blueboard under sidewalks significantly reduces root lifting*.  I would assume the foam would do the same.


*Not to imply that trees/roots are the primary problem.  Often, they are not.  But where there are roots due to other problems, the blueboard makes additional lifting less likely or less pronounced.

[Lynden]

I'd use fence post foam instead of the stuff in a can.

http://www.homedepot.com/p/Sika-33-fl-oz.../205671519

[fredhargis]

How about that, didn't even know that stuff existed.