Walk In Sizing
Help me out here.
Walk in freezer 27x15x9'3"
Kolpak box built in 2006 - insulated floor - combination box (so one 15' wall has +40F exterior temp) - one standard entry door. Walk-in is inside the building.
Desired temp -5F to -10F at the coldest.
14,000 Btuh evap coil
SBFE-B-ZP TXV (1.25 to 2.0 Ton if I remember correctly)
CF12K6E-TF5-270 (230V 3P - 12,000 and change capacity @ -20F and +95F R404A)
Compressor working it's guts out. 26 psig and 270 psig with a box temp of +10F. Superheat +21F (Valve opened full open - suspect it won't feed more due to MOP feature)
I called United today en route to a service call and had them run the calcs on the box. They told me 13,500 for infiltration load and another 9,000 for product load (@ -10F box).
I haven't looked into it in greater detail at this point, but all indications are the equipment is significantly undersized for the box. This thing was installed less than a year ago and compressor is DOA.
Can someone be that far off on load calcs - or do you think I'm just missing something?
Kinda vague - just thought I'd throw it out there before doing my own homework
whats stored in it, and what temp is the product coming in? it has a comon wall with the cooler? wheres the condensor? any exterior walls and is it in conditioned space?
these should all be on the sheet when you try and calc out the size, could change the size
Like I said - kinda vague. I'm gonna load calc it myself, but in giving United the information, they came back with 22,000+
Originally Posted by Mstrav
Frozen food from/for kitchen (big kitchen) - Product mostly frozen coming in (+5F entering temp for calc purposes) - condensing unit on roof - and yes, the space is conditioned.
United says 22K but there is a nameplate on the box that states 13.9K load. Unfortunately I didn't remember to pull the MN and SN from the box yesterday and Kolpak is unwilling to give me any info regarding their sizing procedures with out it.
if this is a storage box (not pull down) the 22,000 to 24,000 is where it belongs. that's if there no special secret things going on. based on that, you are way undersized, no way to fix without additional or new equipment. quote the right stuff or walk away.
storage freezer 3 primary loads
1. Infiltration - heat coming in through doors
need door size and cu/ft of box plus infiltration RH and Temp
2. Wall gain - heat coming in through walls, floor and ceiling
need square ft of surace area of each wall, ceiling and floor
3. 24 hr product load
there are other loads as well, lighting, equipt, etc, etc
point is load of #2 above exceeds your equipt size
for more info on Refrig Load Sizing get HeatCraft's Manual, it's free
and you can download at:
if you are in the business, this manual is a must, never have a wholesaler size your stuff, do it your self. Bohn supplies a free load calc program as does Russel and others.
I ran this box on the Keeprite box load program using the following parameters:
15W x 27L x 10H w/ Floor
4" Urethane all around
0F Box temp
75F space temp (except one 15' wall at 35F)
Storage/Normal Duty/Light Product Load
90F Ambient / Air-Cooled Unit / 10F TD
18 Hrs/day Operation / Electric Defrost
I came up with a box load of 14,892 Btuh and the program's unit selection for an air-cooled Copeland Hermetic spit out a unit with the CF12K6-TF5 which they say will do 15,900 Btuh at -10F ET / 90F ambient.
That's what the numbers say, but my gut tells me that's still a bit light for that size box.
Before you go much deeper into this I'd recommend checking the compressor against the Copeland Compressor performance calculator program to see if the pump is doing what it's supposed to do.
Last edited by icemeister; 06-19-2007 at 10:05 AM.
Is that 21* SH at the coil?? At 26 PSI you should be under the MOP and valve should be controlling SH. I'd start by putting a new valve in it.
I gotta get my ducks in a row first. It appears to be over amping already - If I change the TXV now and drop the superheat - whoo boy!
Originally Posted by k_fridge
I need performance data on this body and start from scratch.
I downloaded the load calc software from Trenton's website but for some reason I'm unable to enter the wall/ceiling/floor dimensions correctly - WTF?
I plugged your pressures into the Performance Calculator program, adding the 21F evap super heat, 5F subcooling and 40F compressor superheat:
It says you should be drawing 10.5 A (at 230V). The amp check says at 240V the amps should be 10.1 A and at 208V it should be 11.7 A.
would you just stop the whining pleeeeeease.
next thing, your toe will hurt and your thumb will be in your mouth.
The product load at what temp is it going in. And at what ambient is that box.
I see this a lot Pat. A box works perfect till she hits 95. That box sits in an unconditioned space I bet. You watch. Go there tommorow am and I bet she's purring away.
Equipment is undersized. I agree with Rocket. I'd be in the 22k -24k range
Alright, I guess I had that coming
Originally Posted by Dowadudda
Do you want me to re-type this information in big red letters so you can find it better? ...........
Originally Posted by fordees
Very brief history:
Got called out Sat night - compressor sh!t the bed....it's less than a year old. Installed new body on Sun. Things just didn't look right - temp sluggish comp working its nuts off. Don't want to be responsible for having the next body go out. At very least I need to do my homework and get my recommendations in writing.