Below-grade walk-in freezer

[WinniPEng]

Hello all. I'm working on the HVAC design for a resort, which has a service/storage area in the basement under the suites of one wing of the building. The basement takes up only half of the footprint of this wing, with the other half of the wing on a slab-on-grade. There is to be a walk-in freezer at one end of the basement (under the centre of this building wing). The freezer is 10'x25', is to be kept at -10 F, and has R-25 insulation panels on the walls, floor and ceiling. I am planning on putting in hydronic tubing in the floor slab (below the insulation) to prevent frost heaving of the slab, as the water in the soil underneath the freezer will eventually freeze. However, the freezer is at the end of the basement, where it is adjacent to a foundation wall. How likely is there a risk of freezing the soil on the other side of the wall from the freezer, causing heaving underneath the suites on the slab-on-grade? Would it be necessary to install the radiant tubing in the foundation wall as well, to prevent this? Or would the heat transfer from the suites at room temperature keep the soil underneath in check? Thanks in advance for any input.

 

[atlas06]

You may want to have a separate slab for the freezer.

I've also heard of a technique which consist in running 6" PVC pipes from the plenum (open end) along the outside of the freezer walls, under the freezer slab, and then back to the ceiling plenum along the opposite freezer wall. In a way, running warm ceiling air below the freezer slab from the ceiling plenum.

Never tested it, but i thought I'd throw out there for you.

 

[gepman]

WinniPEng
You will want to prevent freezing on the end wall as well. You can't control the use of the suites and someday it might get cold in there for a while.

I have used the air cooling (as stated by atlas06), glycol circulation, and electric heat trace. They all work well. Since you are in a cold climate (I assume that you are a PEng from Winnipeg) I would use the glycol (as you stated that you were going to do) if you have the waste heat. The electric heat trace may be more convenient for the wall if piping the glycol to the wall is difficult. You still will need conduit for the heat trace cable in the ground. It doesn't use much electricity if you use the self regulating type. You also shift the responsibility from the mechanical to the electrical engineer!