Hi All,

I am hoping to get some practical advise on the issue of hydronic heating of a freezer floor.

Firstly I am interested in the benefits of subcooling my liquid line on a low temperature rack. I am about to quote a new freezer room which is an addition to existing equipment, hence the oportunity to sub cool. I have never used anything other than elactric floor heating in the past.

The freezer has a floor area of about 200 sq M. The rack capacity is approx 45kW (-25 deg C SST and 48 deg C SDT for those that need to know) at full load. If I allow about 10 kW as the heat I would like to be removed from the liquid line (well in excess of what the freezer floor requires i know). My problem becomes the amount of PEX pipe required to dissipate that heat to the ground/base slab at approx 0.35W/M/K. If I don't get rid of the heat then the glycol or water temperature would rise to a point that the subcooling would become minimal I am guessing.

So along with peoples thoughts my question is:

If I ran a copper loop under the base slab rather than in the slab can anyone see issues with this. I am suggesting copper because of the higher heat transfer (28W/M/K). I am also suggesting under the slab so the copper can move a little if it needs to. Copper water pipes have been run to peoples houses for years. If I run PEX pipe I will need a massive run of pipe as well as a large Td which will almost negate the subcooling potential. I am hoping for 20K or better.

Looking forward to the input.

Regards

Rob