waste of refrigeration

[abcdefg1675]

Have you ever been to safeway or super-1 where theres a few long rows of refrigerators, ones that hold beer water pop yogurt and other items. Im wondering, why do they not have doors on them? I can hear the compressers roaring all of the time. The condensing units are under the long 100 foot or so long refrigerator. What is the point of having no doors, airconditioning the air near the condensing unit so it just heats back up?

[benncool]

What you hear running are the evaporator fans or condensation fans. Any modern supermarket has a machine room out in the back of the store somewhere.

In the last 20 years it is common to have 2 racks of compressors. One set is for all the low temperature freezers and the other is for the medium temperature cases. Where I live these systems have 2 condensers. One is on the roof. This is used in the summer time. The second one is located in the buildings ductwork. This condenser is called a reheat coil. That is the reason it is in the ductwork. It reheats the store.

The doors do save energy. Super markets are very cost conscience. If they can save a nickle they will.

I reread your post. Open cases, as they are know, have air curtains. They aren't quite as good as doors but the way they figure it is if you have 2 hands free you will pick up 2 -six packs of soda pop instead of 1. But yes it is an energy lost but not as bad as you might imagin.

[condenseddave]

Benny's here!

And he more than adequately answered the question.

[benncool]

Hi Dave. Yes I decided to see the world. I'm too old to join the Navy.

I invited everyone over to H-talk. lol

[condenseddave]

You wouldn't like the Navy, anyway.

This is a great forum. More info than you can shake a stick at!

[abcdefg1675]

Im pretty sure the condensing units are underneath the rows of refrigerators. There is lots of hot air coming out from vents beneath it.

[benncool]

Well I always tell my technicians that if you are going to make any assumptions about a refrigeration system you should first locate the four basic parts of the system.

The next time you are in that store see if you can find out where the condensing units are and how they get to them in order to service them.

[Abe]

"There is lots of hot air coming out from vents beneath it."

I know where the lot of Hot AIR is coming from, and Im seeing.............Red

[abcdefg1675]

Im not going to go though the grocery store finding out information about their refrigeration systems. I just didnt understand why they dont spend a few thousand dollars for the doors. It would eventually pay for itself. Where i live theirs been problems with the power company, something about selling power to california. If people are worried about saving energy, then why not?

[condenseddave]

When you weigh the benefits vs. the labor involved to keep them stocked and clean, you'll find it's cheaper in the long run to install open medium temp cases. (I don't know if any of the larger supermarket case manufacturers are producing meat, produce, and dairy cases with doors, at this point in time. It would be a real nightmare to keep these cases looking presentable.

As far as low temp cases, glass doors vs. multi deck cases are a substantial energy savings. I recall removing a 72' lineup of multi-deck frozen cases, and installing the same length of used 10+ y/o glass doors, and shutting down a 20HP compressor on the rack permanently. The rack almost never maintained suction pressure before the changeout, yet had no problem, and in fact, actually cycled compressors down with the change in cases.

Bennycool mentioned the "air curtain" in the open medium temp cases, and this does, in fact, serve as a sort of "door", for lack of a better term. A simple smoke test will prove this, provided there is no air infiltration from the stores' HVAC system into the case, which would render the curtain useless, and often causes evaporator coils to ice up, until a technician "looks up."

Often, several techs fail to look skyward when coils ice, thus having repeat calls.

The savings, again, would be relatively minimal, although I understand your concern for saving energy anywhere you can. The single most important thing to a grocer, though, is always marketing and appearance. If the customer can't see something easily, they'll often pass it by. Multi-deck dairy and meat cases are very "viewable", compared to glass doors. Also, with product in glass doors, people tend to hold the doors open while they read labels, look for pricetags, etc. this drives up the energy usage, and temporarily fogs the glass. When the glass fogs, electric heaters are employed to defog them. Another energy penalty.

In the end, it all evens out.