Hi Sergei

R404a will be the refrigerant, the plant does not exist at present. My head pressure will be as low as the valves will handle, have not looked too close at that yet but my compressor limit is 5 deg C SDT according to the data. Obviously I would expect mechanical valves will require substantually more than this and my ambient temperatures would rarely (if ever) allow this low a temperature anyway. It is me pushing the energy efficientcy side of things, I do not think EEV's will be in the budget as I am trying to get other items included (for other equipment) before going there, but I will try. I have had wonderful results with them and low condensing pressures. My customer wants "cheap and simple". Total cost of ownership is not always easy to sell but on machinery of this size savings can be substabtial.

I also understand that my liquid temperature will probably not change too much between summer and winter
by having a PHE cooled by the ground under the freezer. This means that the subcooling will drop away substantually during winter months when the head pressure drops considerably.

It may even mean that the liquid line is providing little to no heat to the floor through winter, but should more than make up for it in Summer. My heat load through the floor is only about 1500W. i have not tried this before and am interested to see the results, If it is ultimately insufficient heat then it is no big deal to swap over to a de-superheater to up the glycol temperature or even use an air to liquid fan forced heat exchanger. I will not be running high discharge pressures just to keep the liqiud temperature up to heat the floor, The saving grace for me in an "experiment" like this is that the freezer will take a long time to hit a danger point and I will gain some practical knowledge, rather than theoretical. I built a freezer half this size that has not energized the heaters after 10 years. I know a bigger freezer will have a bigger need for heating but it is truely amazing how long it takes to get to that point. I guess soil conditions play a big part here.

By constantly providing heat from the liquid line rather than waiting till heat is needed to prevent freezing than sub soil temperatures may not drop much at all.