floor construction of walk-in freezer

[rickitek]

i have this walk-in freezer with cracked floors(bulging). what is the typical design in constructing the floor of walk-in freezer maintaining -20C room temp. the room is located in ground floor. thanks!

 

[EnergyProfessional]

I would think the slab is on a layer of insulation, that also helps with thermal stress.

Obvioulsy all things can go wrong, lack of vapor barrier can cause freezing damage, bad underlayment, too thin.....

 

[chicopee]

Sound like frost heave, so it appears that somebody messed up in the construction or design.

 

[BronYrAur]

I haven't done many, but the ones I have done all had radiant heat tubing under the floor. Not to heat the floor, but to prevent the freezer from freezing the ground below. The ones I did had glycol tubing, but I have heard that just blowing air through small "ductwork" under the concrete works too. If you Google "freezer permafrost" you should come up with a lot of info. Here is a Wirsbo link:

http://www.uponor-usa.com/Misc/Applications/Permafrost-good.aspx

The heat sources on my jobs were done by others and used refrigeration rejection heat to warm the water. I don't remember the temperatures off hand, but the supply was something like 70 deg F. The return coming back was very cold to the touch. So much so that we had to insulate it to prevent sweating. Probably 50 deg F or less. Again, the point is to just keep the ground from freezing - nothing more.

 

[mtngreen]

Freezers require an underfloor heating system as explained above or the frost will heave the concrete. Either a radiant system (typically operates at 60F) or an underslab ventilation system, either forced or gravity.

 

[EnergyProfessional]

I think underslab ventialtion will cause all kinds of problems like mold etc. Use glycol as described above.

 

[rickitek]

some contractors i talked says it doesnt need to put heating systems but i'll go with the installation of heating system using heating cables to be sure. and some articles ive read over the net says drain pipes beneath the floor should be installed to drain water or condensate but some did not mention it. is it really need?

 

[BronYrAur]

I would think that answer is entirely dependent on the soil conditions, elevations, etc. There should be a good vapor barrier between freezer and ground, so I don't think the water would be coming from the freezer.

You might want drains in the freezer itself in the even of a water leak or something else, but I don't think you need them for the permafrost protection.

 

[rickitek]

yes, i already finalized the plan and no need to install drain pipes beneath the floor. as i read on some articles aside from draining they use it also as heating system using natural draft. thanks everyone for all the replies!