convert cooler to freezer

[jayjay]

I have a blast cooler that I wanted to convert to a freezer. Is this very difficult? Other then the comperssor, heat at doors what else would be a problem. The existing floor is concrete the unit is on the second floor so air will move under the floor. I would have no thermal break from the freezer to the rest of the floor. Can I add insulation to the floor and cover with a new floor?

[Electrocoolman]

JayJay.
Dont know about floor, but you will also need an air equalising valve fitted through the wall....these also need to be heated.

[Peter_1]

You can add a second floor above the concrete.
Install a small electric heating between the two, controlled by a thermostat of if possible, provide an airspace.

Change of gass, what's in it for the moment?

Electrical defrost with heated drainpipe if not already fitted.

If your compressor was selected for a blast cooler, then you propably can use the same compressor. What's the compressor and evaporator brand name and type?

Look if the light fits (no TL light in the freezer)

[jayjay]

I'm ok with all that stuff its the floor I'm really worried about. What if I install electric heaters under the slab. It's about 6" thick will that keep the floor from freezing

[Andy W]

Door frame heater if it has not already got one, drain heater, presure releif valve and re calculate the equipment which is already fitted, maybe just maybe the blast chill equipment is capable of lower evaporating temperatures and will achieve blast temperature over a longer period of time.

[jayjay]

Adding a layer of insulated flooring is required?

[TXiceman]

You need to add an insulated floor above the existing floor. JM2CW (just my 2 cents worth).

Ken

[Peter_1]

I suppose 6" is 15 cm, right Jayjay?:o
Try always to convert your IP units in SI units, these IP units are difficult to read for many posters.

15 cm is not that much for a freezer.
How will you insert heaters in the slab?
Is the floor connected to the walls without anu cold-bridge? This is very important because you otherwise have a very god conductor to the ground. Don't forget you wll increase your DT over the floor now with 20 K and this additional DT passes through the freezing point of the slab.

[jayjay]

Peter thanks for info
The walls are sitting on the concrete. I was hoping that because the unit is on the second floor just the air under the floor would be o.k to prevent the concrete from freezing and I wouldn't need heaters. Can I install a floor inside the unit? What does DT mean? I'm a carpenter not a refrigeration guy

[Peter_1]

DT is the temperature difference. How larger the DT, how more danger for problems, especially when you go below the freezing point of water which is 0°C (or ...°F?)

If the panels are mounted on the concrete, then you have to do the following: install at least 14 cm floor isolation (you can do easily the conversions with Uconeer :D )

Very important, remove 12 cm of the inner steel wall from all the vertical panels, starting from the bottom, the whole freezer around so that the cold of the freezer can't go down via conduction under the floor.

Problem can be the door perhaps.

Install an electrical heating mat on the floor, the same they use for floor heating, install at least 2 circuits in case one fails.
Install 2 probes in a small tube in the center of the floor ,not to close to a heater.
Poor equalization concrete (don't know the correct English name for it) over the heaters and the probes with a thickness so that they're embedded in the concrete and you get a flat surface.

Another solution can be that you lay small wooden lats on the floor of +/- 2 cm thick (Uconeer you know) and lay the heating between the space between the lats. You don't need concrete then.

Buy a special floor panel made for this purpose so that it can width stand the load above it or make it yourself.
Anyhow, leave a gap between wall and floor so that you can inject PU between it out of the small pressurized bottles so that the floor fits 100% with the walls.

In case you want to make he floor yourself: use PU panels with steel on both sides and a density of +/- 40kg/m³.
Lay a water-resistant multi-wood panel on it, and afterward lay a sheet of aluminum above it.
Or buy 2 component PU poor floor, mix it and poor it on the floor. Throw some quartz particles or a little bit dry sand in i. You then have a very nice looking floor like you see in trailers.

Connect the heaters and connect both probes to a thermostat. One thermostat switches on the heaters if floor goes below 5°C (eventually during night at lower rates) and the second is set at 3°C as a safety thermostat.

All this can be done in 1 day with 2 man, except addaption of the door.

[Dan]

You will need a vapor barrier and insulation on the underside of the floor, otherwise you will form moisture or ice on the underside. You will also have conduction around the exterior on the topside of the floor forming moisture or ice. For this, you might consider a perimeter heating wire and an insulated curb over the heater. Your idea may work, but expect to have problems that require additional solutions.

[Peter_1]

Dan, the panels with steel on both sides are made of PU and have the best vapor barrier: steel.
These are the same panels as used for the walls.
The forming of moisture is prevented by the heating by 'pushing' the dewpoint away from the concrete floor.

You will also have conduction around the exterior on the topside of the floor forming moisture or ice.
This isn't clear for me because teh way I see it, if you prevent a coldbridge then ice can't be formed.

The construction I described is how an industrial freezer floor is made.

[Dan]

Peter, I did not see your second post when I made my small suggestions. A built up floor with a thermal break (Ice-bridge?) at the walls is an excellent idea. I was just looking at the situation from the outside. If the ceiling of the room below were insulated, and the perimeter of the concrete around the box was dealt with, it would be possible to avoid a built up floor. I am assuming forklift traffic, which eventually destroys built up floors, and has the disadvantage of a ramp of some sort.

I was thinking along the liines of adapting the exterior components, whereas you are suggesting the interior requirement adaptation if I understand you correctly.

Your suggestions are very good ones as long as a raised floor does not cause problems from heavy traffic.

[jayjay]

Thats alot of work. It might be cheaper to buy a new unit that fits inside the existing cooler? Building up the floor is tough because of the ramp. If the ramp is inside I loose space inside. and I can't get much insulation under the floor where it ramps down to the existing floor. If I ramp on the outside its in a hallway that may cause other problems.
You don't think I could heat the floor from below and maybe a foot or so past the unit install a reflector sheild and then spray insulation underneath all around under the floor and thats it?

[Peter_1]

No, it won't work, you have to avoid cold bridges - epsecially with freezers - and spraying underneath the floor doesn't prevent this.
You could damage the whole building wit this, look once to this thread http://www.refrigeration-engineer.com/forums/showthread.php?t=3965 and to the pictures I posted

[Peter_1]

Jayjay, why sitting on your money, being a landlord :D :p

[bobkellyb]

Forget the floor! If the room was (is) a medium
temp. The wall and roof panels won't have the insulation properties needed for a low temp. (Freezer)
Refrigeration components will need to be replaced with correct size and type...........

[Peter_1]

You can be right but don't forget, it was a blast cooler.
Jayjay, what's the panel thickness and can you specify more precise the main components?

[bobkellyb]

Forget about the floor! If the panels are designed for medium temp. forget about running the room as a freezer.
Also the evaporator will not have defrost heaters, the condensing unit (if suitable for low temp app.)
and evaporator will not have the capacity to do the job at the lower temps.
Bob..

[Peter_1]

If the condensing unit can run for a cooler application, then it fits mostly for a freezer.
If we install a blast cooler, then its range is already in that working area where you need heaters to defrost it, isn't it?

If the evaporator was orginlally calculated with a Dt of 6K (=common practice with a blast cooler) then its capacity will not decrease when using it in a freezer application running at a DT of 10K.
It all depends how you look at it.

How can you be sure that it will not work? We have applications where the spaces can cool and freeze, running on R404a.

If Jayjay has some luck and his system was running on R134a or a similar gass, then the compressor possible can be converted to R404a so that its capacity increases and matches again the evaporator capacity.

[Peter_1]

If the condensing unit can run for a cooler application, then it fits mostly for a freezer.
If we install a blast cooler, then its range is already in that working area where you need heaters to defrost it, isn't it?

If the evaporator was orginlally calculated with a Dt of 6K (=common practice with a blast cooler) then its capacity will not decrease when using it in a freezer application running at a DT of 10K.
It all depends how you look at it.

How can you be sure that it will not work? We have applications where the spaces can cool and freeze, running on R404a.

If Jayjay has some luck and his cooler was running on R134a or a similar gass, then the compressor possible can be converted to R404a so that its capacity increases and matches again the evaporator capacity.

Don't forget that most freezer compressors are running far below their max allowable current

[jayjay]

Jayjay, why sitting on your money, being a landlord :D :p

What's this mean?

[jayjay]

Once again never a simple solution. I will look at the units and get back to you. Maybe I can lift the unit and install a floor under it so the walls are sitting on the insulated floor with heat and everything else required.

[Peter_1]

What's this mean?

Your profiles says you're a landlord;)