Changing of a freezer room to coolroom

[bodytouch]

Hi all,

I have a Zanotti uni block BSB series unit that is currently running a freezer room. My customer would like it to be changed over into a coolroom. My thoughts behind this are YES, it can... am i correct?

At the moment it has a CPR which is leaking gas, if this now is going to be used as a coolroom, a CPR will no longer be required correct? so this can be taken out.

Im in the process of sourcing the paramters cheat sheet.(if anyone has.. please let me know.) If i change the setpoint to 2deg C, defrost duration to 5-7mins.. keeping in mind heaters will still be connected, defrost termination to 25 deg C and number of defrosts to 4 a day i should be ok?


not looking forward to this job.

Regards

David

[old gas bottle]

well you have got one right out of that lot,have you been doing this job long ?

[nike123]

Hi all,

I have a Zanotti uni block BSB series unit that is currently running a freezer room. My customer would like it to be changed over into a coolroom. My thoughts behind this are YES, it can... am i correct?

No, you are not correct!

At the moment it has a CPR which is leaking gas, if this now is going to be used as a coolroom, a CPR will no longer be required correct? so this can be taken out.

Do you know what is CPR function?

Im in the process of sourcing the paramters cheat sheet.(if anyone has.. please let me know.) If i change the setpoint to 2deg C, defrost duration to 5-7mins.. keeping in mind heaters will still be connected, defrost termination to 25 deg C and number of defrosts to 4 a day i should be ok?

No, it will not be OK!

not looking forward to this job.

That feeling is just right for that job.

When you changing evaporation temperature (and condensation temperature), compressor capacity changes because of different gas density at different temperatures and constant displacement volume in time period. Higher compressor capacity (in this case) mean bigger condenser. That is why is CPR installed to maintain that capacity in borders, during pull down.
Next, for that increased compressor capacity you should have bigger active surface of evaporator with different air flow rate to be able to evaporate higher amount of refrigerant or you will have liquid flood back. And last, that higher refrigeration capacity of compressor mean that, now, expansion device is small.
That is why Zanotti have MSB serie.

[bodytouch]

Thanks for your reply, much appreciated. will message you personally to get some more advice.

Thanks

[askats77]

Hi. I am new to this forum. I have changed freezers to coolers many times. I just did that for a pizza chain. The only thing you need to be aware of is that the fan delay wiring will have to be altered so that the fan will not shut off if the coil temp is above the control set point. I don't see that it would be desirable to remove the cpr valve. You will be running even a higher back pressure and the cpr valve will protect the compressor. I leave the heaters connected and use about a 10 minute defrost with a defrost limit switch wired in. I have found that a termination switch will activate and not allow any defrost time at all.

[askats77]

Just read your reply to guy wanting to change freezer to cooler. You are very astute technically. But practically, I think that if the tech. is careful to adjust the expansion valve, he will have no problems. I have done this many times and there have been no problems and the system has performed well. If it does have problems, then the components can be changed to proper sizes, but there is no point in doing this now.

[nike123]

Just read your reply to guy wanting to change freezer to cooler. You are very astute technically. But practically, I think that if the tech. is careful to adjust the expansion valve, he will have no problems. I have done this many times and there have been no problems and the system has performed well. If it does have problems, then the components can be changed to proper sizes, but there is no point in doing this now.

Sorry, but if your compressor have capacity of say 4kW at -30°C evaporation and 10kW at -10°C where did you are going reject that additional heat?
When you say that "I think that if the tech. is careful to adjust the expansion valve, he will have no problems",
do you think that is OK to run evaporator superheat of 25K or more to compensate for that?

Or you maybe doing it in some other way?
Please, explain your adjustments and help me to understand how to do that without major changes. I have lot of request of that nature which I did not fulfilled.
Maybe I could do that if you explain to me what you do.

[old gas bottle]

well i have done it before when needs must ,but the CPR must stay and set to a safe pressure to protect the compressor and reduce the cappacity upto normal running temperature.[start about 1 bar]

i would disconnect the heaters and run the evap fans continiously,either via the controller or altering the wiring,

reset the high and low temp alarms,if set in controller

widen the diff to 3 deg C,

4 x d/f 24hr x 20 mins,

no fan stop temp or set about 20 deg C.

disconnect door heater.

thats how i would do it to run @ max of 1 deg C.

[nh3wizard]

Im sorry, what did you say I was to busy looking

[bodytouch]

Thanks all for your input.