View Full Version : Evaporator Sizing??

03-05-2010, 10:06 PM
Hi guys i have a Friga Bohn evaporator in a walk in freezer, evap is really old and 2 of the electric heaters have failed and customer has asked me to replace it, problem is that the data plate for the evaporator is missing and basically i need to get a match up to get the same size evap. I got the info off the compressor (condensor data plate missing as well) and gave that to climate centre (to get a match) along with coldroom size etc, they got back to me and said that the compressor is not for a freezer and will not work so they cannot match an evaporator to it??? The condensor is 2 year old according to customer and as far as it being the wrong compressor the freezer pulls down to -20 in no time, so climate have been no help, i have also been to HRP and they have not been able to help either. The customer will not want a whole new system installed when everything basically works ok so i need to match the evaporator somehow. The evaporator is a Friga Bohn, 2 fan unit, square fan guards,980mm x 370mm x 400mm(height), coldroom is 1650mm x 1600mm by approx 7ft high, compressor is Lunite Herm FH4524Z on r404a, if anyone can give me any advice with this that will be great, thanks

Also can anybody tell me a good uk supplier for door heaters for walk in freezers??
Thanks again :rolleyes:

monkey spanners
03-05-2010, 10:52 PM
Hi Northdude,

That comp is a HBP one rated down to -15c in the catalogue, at which temp it does 2397W, its 2hp.

The nearest LBP L'unite ones are a 1.5hp CAJ2464ZBR which does 1995W at -15c or the 2hp FH2480ZBR which does 2980W at -15c, both these comps are rated down to -35c evaporating temp.

So it seem yours would be about 1 3/4hp in the equivalent LBP comp if such a thing existed.

Why not get the evap and tev/orifice sized for both 1.5hp and 2hp low temp comps and pick the one which fits nearest what is there already.

On the few times i've had jobs like these i make a note of fan motor/blade size, tev/orifice size, pipe size etc the more info the better.

Jon :)

03-05-2010, 11:09 PM
Hi Jon, thanks for the advice mate, been trying to sort it out for about 2 weeks the unit must be looking like an ice cube by now with the heaters down lol, thanks again !! :D

monkey spanners
03-05-2010, 11:17 PM
No worries! and another thing i've just remembered is fins per inch on the coil as these are different depending on what temp the evap is running at, low temp has less fins per inch so there is more room for ice before it blocks airflow and needs a defrost.

More info the better, usually i take some pics with the phone too if its something odd.


09-05-2010, 07:50 PM
who can i seclect capillary tube for different type of compressor & it cooling capacity

monkey spanners
09-05-2010, 08:03 PM
who can i seclect capillary tube for different type of compressor & it cooling capacity

Have a look on google (or another seach thing) for 'dan cap' from danfoss.
There is some other software as well but i forget what its called :D

09-05-2010, 08:36 PM
Match the evap to the box. That way you have a known good. Advise the customer he has a med temp compressor. When it craps out he can change the condenser then and have a matched set.

10-05-2010, 08:38 AM
you need to match the evap to the room size, going on your dimensions i would expect it to be a searle ks20/4 with electric heaters, then why dont you hide the price of a new compressor in your quote to get a low temp compressor ie a caj2464z this is a low temp compressor and should do you a turn.

09-06-2010, 12:12 AM
Got the evaporator matched to a CAJ2464ZBR compressor and the room size, the new evaporator is a searle 3.5g (evap coil on the front and slanty back with 2 fans), installed it today and having a complete nightmare, the room pulls to around -5 and evaporator coil is completley icing up and room not pulling down any further than -5. Anybody any ideas? undersized evaporator? I fitted a new expansion valve but the orophus on the old evaporator was a no2 and the one i have fitted on the new valve is a no1 (as instructed by climate centre), could this be a cause?? any help will be great as customers stock is virtually in the defrosting stage! :rolleyes:

mad fridgie
09-06-2010, 12:27 AM
Does the room, have un frozen stock in it? If so then this why you are unable to bring it down.
We need more details, pressures and temps. the more info the greater we can assist

09-06-2010, 01:30 PM
your back pressure should give you the answer

09-06-2010, 04:04 PM
thanks for the quick responses, think it was down to the stock not being completley frozen, after replacing the evaporator the stock still appeared frozen but oviousley not, managed to get it down to -15 now so the panic is over, because i wasnt sure about the evaporator being the right size it triggered me to think that it was the wrong size and panic panic panic, set it for quite a few defrosts overnight and been gradually lowering the setpoint, and its pulling down ice free, cheers

29-06-2010, 09:57 AM
Some body give me the tips how to balance the CO2 refrigeration system.