question for the HVAC experts

Ray IN · May 12, 2019

I know nothing about refrigeration, but I just got a too-good-to-pass-up deal on a 8 x 20 ft walk in cooler, without any cooling equipment.

I will either use a large window air conditioner in it or a mobile home unit that is self contained on the outside. I do not forsee wanting to cool it to refrigeration temp, but rather will keep it at 50--60 degrees to store produce. If I go colder, then produce does not do well when you take it out to sell in the open air. I talking green beans, sweetcorn, onions, squash, etc.

I know I can get a device called a "Coolbot" for about $300 that will control the window air conditioner to go to lower temperatures than normal. What suggestions do you have on size of unit, circulation fans,etc.

Steve@Advance · May 12, 2019

I don't think you would need a large window unit.

Could probably get by with a 5-6000 BTU, maybe go up to a 10,000 just to get a little better quality unit.

As well insulated and sealed as a cooler is, a small unit should have no problem cooling it. The only thing that would load it would be bringing in large quantities of product. But even then, it would still have no problem eventually bringing the temp down.

The typical window unit will set down to 60F. You might want to check to be sure, but that is typically the industry standard. Spending $300 to go a few degrees lower seems impractical.

You could add a small circulating fan to get even temperature distribution.

I say go for it!

guido · May 12, 2019

Hello Ray Tractor,

You need to know know all three dimensions to establish B.T.U requirements. Insulation too makes a difference in the calculations. Then you can oversize the unit, to keep your temp. I would think that you will also need a shaded area, and or more insulation. 5 thousand B.T.U,S will do an average sised 8x10 room with 8 foot ceiling, or an area of 8x10x8 approximatly

Guido.

da.bees · May 12, 2019

I agree with Guido and steve,try a 5k to 8k unit before buying special controls.
Here's suggestions that will help.
Make sure evaporator coils are clean(car wash work's great). That helps prevent frozen coil.
Set fan to run continuous. This also help's prevent frozen coil.
If you must go in and out a lot,fill surplus space with foam blocks,coolers and ice chests,even 5 gallon buckets with lids. This reduce's cu ft of air that exchange's through door and less warm air that must be cooled down after door has been opened.
To help unit cool large amount of new produce,fill those buckets and other containers with water. Smaller containers for better circulation and metal containers are best but plastic is good.

Donaldinky · May 12, 2019

Its an ac unit. Most r good to 68 degree they will freeze up on cool night. Head pressure will fall and low side pressure will drop out. Its an A.C. unit not refrigeration unit. No defrost need fan cycle for control of head pressure. It only has one motor for both evaporator and condenser fans. Be better off finding a small refrigeration unit to match the unit. When it freezes up liquid will destroy the compressor it a vapor pump not liquid. Be like try to pump water with a air compressor. The compressor on ac unit are high temp. Not med. Temp u will be nothing but trouble.

Bob · May 12, 2019

Although costly, the "CoolBot" looks like a pretty neat deal to me, since it requires no permanent mods to the window AC.

The fact that it monitors coil temperature and controls freezeup becomes more important the more you need to drop below normal room temperature.

Used AC's usually aren't to hard to come by at a reasonable price, you could try one without a big investment, rig up the "CoolBot", and give it a try.

If too small, you wouldn't be out much to switch it out if you have to move up to a larger one, and the "CoolBot" would transfer easily.

Geo-TH,In · May 13, 2019

Make sure condenser is clean too.

JWA · May 13, 2019

U-tube is your friend. You will find several suggestions for what you are wanting to do using an inexpensive electronic temp. controller, not the more expensive cool bot.

big jt · May 13, 2019

I know it really isn't relavant to the question you asked but 50 or 60 isn't cold enough to store produce for retail sale. Food inspecter will nail you on this one and make you throw everything that has been there for more than 4 hours out. Been there/done that.

The NO zone for food storage is 40 to 140.

Sorry to be a YT Health inspector but wanted everyone to know those temps aren't allowed by the real inspectors.

jt

Bob · May 13, 2019

(quoted from post at 10:35:54 05/13/19) I know it really isn't relavant to the question you asked but 50 or 60 isn't cold enough to store produce for retail sale. Food inspecter will nail you on this one and make you throw everything that has been there for more than 4 hours out. Been there/done that.

The NO zone for food storage is 40 to 140.

Sorry to be a YT Health inspector but wanted everyone to know those temps aren't allowed by the real inspectors.

jt

big, you mite take a look at the link below.

https://extension.umaine.edu/publications/4135e/

big jt · May 13, 2019

Course most of those temps are in 32 to 40 range. Quite interesting that Tomatoes are allowed up in the 50s. The first thing the inspector does when he drops in on us is get out
his thermometer. He has told us that if a cooler is above 40 and has been for more than 4 hours all contents have to go in the trash.

Once again don't want to hijack the OP here just wanted us to all be safe in our food handling and esp if it is for retail.

We involved the health department before we even opened the door and they have been very good to work with.

jt

question for the HVAC experts

Ray IN

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Steve@Advance

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guido

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da.bees

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Donaldinky

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Bob

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Geo-TH,In

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JWA

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big jt

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Bob

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big jt

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