View Full Version : Sizeing condensing units

24-11-2004, 10:13 PM
Hi Guys,

I wrote the same sort of post last year on a/c but now my job change has brought me into contact with a lot more cellar cooling.

I have lots of old R12 units that the outdoor units are long past their best and need to know what calculations are needed to size an outdoor unit.

Now obviously normally i would take the details of the current unit and match up the size but a lot of them have no labels any more.

Is there a quick calculation, if so can you let me know



24-11-2004, 11:10 PM
not sure of the calculations, but what we do is this:
check the Thermofrost or HRP catalogue and they give kw ratings for above or below ground beer cellers based on a m2 basis.

hope this helps.



25-11-2004, 07:39 AM
You can size the condensing unit by checking the rating of the evaporator and TEV

25-11-2004, 11:27 AM
There are various computer programes for sizing units.I normally give the wholesalers the size of the evaporator and let them come up with the unit size.This way if there is a problem you have some comeback.Most of them will bend over backwards to help you if they think there is a sale in it.
Sometimes the rooms were not sized correctly in the first place.So I normally take all the particulars for heat load calculation and come back to the client with the size it should of been.Some clients may even then go for an evap change also.
I had this problem once where a condensing unit was changed on a freezer room.I informed the client that the entire system was undersized but he wanted to keep the original evaporator and replace the condensing unit with one of equivelant size.We did that and even though the system was operating properly it took days to reach temp.The reason it took so long was because the room had been without refrigeration for a few days and the room was waterlogged. Once the water in the walls refroze operation went back to normal.If the unit was correctly sized we may not have noticed this.

25-11-2004, 10:26 PM
Guess what...............I received a present this morning........
Hawco refrigeration kindly sent me a CD
And its got Mistral software on it...............

I dont like the idea of phoning the wholesalers , giving them all this info and a day later they size it all up for you

I prefer to do it myself.

Also the wholesalers bump it up, ( oversize) it.

Cryo used to do a good cellar calculator.........

Ive got a hunch...........how about using a ac calculator to size up a cellar ????

See your Hawco rep...........see if he gives you a CD

Why pay that company..........which charges 500 or so for their software.................( Which I found to be crap )