Endless Freezer as Endless Cooler (10 door)

[herefishy]

Mr. customer said "I'm buyin' two (used) 5-door (glass) merchandisers, and I need you to provide a condensing unit and do the install." They're endless glass door merchandisers. He's buyin' used (refurbished) equipment after turning down my quote for NEW MasterBilt brand matched cases and C.U.

So, I use my guidebook thingy, and determine a required capacity of about 12,400 btuh @20degF SST. I make a selection and get it coming via the distributor.

And guess what? Two 5-glass-door freezers arrive!!!! Now according to my guidebook thingy, I estimate the required capacity of these cases to be about 17,000 btuh @ -15degF SST, or perhaps 1,133 btuh/degFTD, assuming a 15degF TD. Whereas I assumed a evaporator capacity of about 820btuh/degFTD for the 12,400btuh rule-of-thumb load.

I decided, no problem, I'll just disable a couple of (the 10) evaporator fan motors in order to decrease NRE of the evap. In doing so, I decided that I could de-rate the unit about 20% in order to see a 15degFTD (desired 20degF SST) in order to maintain humidity, SH's, etc.

When we started it up, box coming down to near temp, we were running a 23degF SST, thereabouts and SH was a bit high at the evap outlets. I told my tech NOT to fuss with TEV adjustment before "knockin' out" a couple of the evap fan motors. That brought our SST down to 20degF at a 36degF box!!!!!! Great!!

BUT.... the new C.U. (Trenton EH200H2) has a 17 pound receiver. IT'S NOT ENOUGH!! Head pressure rises on pump-down..... and it's no wonder, because we've got more than 17 pounds of gas in the unit.

? Is the discrepancy due to increased evap volume for the higher capacity and lower temps of the freezer app that the cases were designed for?

Should the mfgr standard receiver provided for rated capacities be adequate in most of applications?

Does the endless merchandiser application typically require more than standard receiver capacities (refrigerant charges)?

I've had one other instance, exactly the same with this customer and his piece-a-meal equipment. Freezer cases as cooler cases, and had to re-fit a larger capacity receiver. However, I've applied condensers with properly utilized cases.....NO PROB.

I told Mr. customer that he bought freezers! He called Johnny (refurbished equipment supplier) back, and Johnny said that they were multi-purpose cases! yeah, right.

Of course, we wouldn't be going through this if "Mr. customer" wasn't tryin' to save the buck on the wrong end of the stick.

Also, I'm concerned that my HP is real low. These evaps are fitted with liquid subcoolers before and after the TEV. I don't like it.

What do you think?