Rigging up a walk in cooler

[nchvac]

What kicks me is the mentalitiy. He actually has an old R22 display case that he runs in his basement. He says it runs all the time. Based off what I saw from his A/C unit when I fixed it I am sure it could use a good PM. I think the storage space may be an issue, but if he would maybe insulate the doors and change the seals, as well as PM the unit, being that it is in his basement, he could save a boat load of money on electricity using it instead, but once again the space may be a problem.

[Poodle Head Mikey]

An actual day has 24 hours in it.

A Refrigeration Day has less than 24 hours in it - because some of the hours are taken up by Defrost Time - either off-cycle or powered defrost - doesn't matter which.

Although I find that can cheat the above time-clock somewhat by using reverse cycle defrost - which clears the coil of frost just about Right Now - but the subtracting effect of defrost is Always going to be there to some degree.

Take the total load, which is likely closer to 10K in Real Farmer Life, multiply it by 24 Real Hours and then divide it by about 18 Refrigeration Hours. This makes the load about 13.5K

Then take away probably 25-30% for the compressor loses associated with the lower suction pressure and you need a rated A/C capacity somewhere north of 15K to do this thing.

That being said; no AC coil is going to do it well due to the Way Too Close fin spacing. On window boxes especially they will barely tolerate water - let alone actual frosting - before blocking air flow.

But you might have the best success on this path with two largish (for the load) window units - one can run while the other defrosts. But unless you get those for free - it's funding spent unwisely. And getting the space lower than maybe the high 50's is going to be tough to accomplish on any regular basis.

You best hope to do this thing 'cheap & dirty' is with a real refrigeration evap piped to an air conditioning unit. I have a bunch of those running for years in Porto Rico and a few around here for friends.

PHM
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My gosh, I have to ask this. I am hoping to intrigue Poodle Head or some of the older techs here that have seen it all.
I have a farmer friend of the family that sells produce. He is trying to rig up walk in cooler, and when i say trying, I mean he has already done it. He has an 8 x 10 utility building with R13 insulation and drywall nicely finished. The door is sealed up pretty decent. He has a concrete floor, couple shelves.
Now here is the kicker. He is using a 5,000 btu window air conditioner to cool this contraption. Of course the a/c unit only goes down to 60, but it is maintaining 60 except the other day when it got up to 95 outdoor ambient he said it got up to 70.
So he is asking me if I can make the unit cool lower than 60, preferably around 45, but 50 would be ok, but really he wants 45. I said I would have to have a medium temp stat and cycle the compressor with it. Of course I will have to have a coil temp of about 25 to get 45 if I recall, and my biggest worry is that if I can get it down to 45 with this A/C unit is how low will it take the humidity down, because you don't want low humidity with produce. Oh and I told him when it got to 95 he would probably need to have a fine mist of water spraying on the condensor coil.

For the time being I moved the temp sensor of the a/c away from the coil, so maybe it will drop a couple more degrees. I know this is kind of funny, but you got to give the guy props for trying, and he is a farmer so I am wanting to help him out some if I can. Now I haven't done a load calc on a cooler in about 3 years, so I am wondering what btu removal is required to cool a structure like this down to 45 degrees. Again it is 8 x 10, probably 8 foot celing, R13 insulation with drywall, something like wood sheathing sideing. I don't know if we can use the U values from manual N on a refrigeration calc, but don't see why not.
He just asked me right now if the 5000 btu is enough. maybe I could plug the numbers in on my load calc program with a 55 degree TD. Wow, that sounds like it would take a lot of btu's. Kind of interesting, but mostly entertaining this is. I am really hoping that he had this building already constructed for another purpose and just decided to try this out. I am pretty sure he is willing to buy a bigger A/C unit to get it to work though.

[VTP99]

If I were to try "rigging" something, here is what I would do:

Take a two ton AC condenser (junker 10 seer) and set it outside the building/shed . Take 1/2 copper pipe(just use type M and flush it), and use it to make a "coil" that that basically looks like radiant piping and hang it from the ceiling. Use a TXV and there you go. I know for a fact that this type of thing works, and no worry about loss of humidity. The coils will frost up, but will drip off during off cycle. I have seen an a very old Ice house that had an ammonia chiller that worked like that. You might have to play with the design a bit, say like using a header and multiple circuits to get better balance and so on.

I have seen that done as well. And I would not believe it had I not seen it.

[CoolWine]

That "cooler" better have a real good vapor barrier if he doesn't want rot & mold.

[Poodle Head Mikey]

The freezer room walls are (were <g>) lined with horizontal passes of black iron pipe. On very old systems the u-bends are actual one-piece cast iron fittings.

Each freezer room had a hammer sitting by the door. Every shift a guy went around smashing the ice off the pipes. That was the low-man - the more senior guy would also go around but he would only check and maybe adjust the hand expansion valve. <g>

Huge, tall, slow (you could touch the flywheel) Frick compressors with a 6' diameter flywheel.

Speaking of systems that no one would work on - As a kid, with more balls maybe than brains, I went out on a freezer warehouse job, checked the 12" diameter panel gauges and found that it was an R-12 system. Huge, Really heavy, slow piston compressors. I worked on the system for a good while before I realized that the gauges were reading in atmospheres of pressure - and not in psi. It was pumping CO2. <g>

The last one I knew of is now some kind of business park development.

"Sic transit purity" would be the Latin phrase. <g>


PHM
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I have seen that done as well. And I would not believe it had I not seen it.

[Wheelbaron]

The one I spoke of is still running. It is a old ice house in S WI, They used to pull ice from Wisconsin river, and store it in there. Now they use it as a warehouse for pallets of bag ice. The owner of the place is an antique buff, and refuses to tear it down an build a new one. The evap is all 1 inch iron pipe, and they only defrost twice a year. The ice gets to about 10" diameter on the pipes. Belt drive unit running on ammonia. Up until a few years ago it was still a canvas belt.

[Poodle Head Mikey]

Get that boy a box of hammers! <g>

PHM
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The one I spoke of is still running. It is a old ice house in S WI, They used to pull ice from Wisconsin river, and store it in there. Now they use it as a warehouse for pallets of bag ice. The owner of the place is an antique buff, and refuses to tear it down an build a new one. The evap is all 1 inch iron pipe, and they only defrost twice a year. The ice gets to about 10" diameter on the pipes. Belt drive unit running on ammonia. Up until a few years ago it was still a canvas belt.

[coolperfect]

When I was a kid we had some old movie houses with Fricks.Water cooled seals, no black pipe r12,A/H D.C. Drive.By the time I was there it had a modern BAC evap. Condenser.I was told the install date was 1935

[Poodle Head Mikey]

A 400 foot water well - water dumped outside into an alley. Huge 100% outside-air through giant water coils mounted in an outside wall. Install date 1919 or 1921 - depending on who you asked.

That same job had a coal-fired furnace, in-floor, hot-air-tube radiant heating system. The air ducts were / are all made of red brick. They thought it was a hot air heating system until I got there to tell them different.

In the 1930's it was converted to DX coils and open-drive R-12 compressors.

In the 1960's converted to a 35 HP R-22 condensing unit with a 35 Copie in it. Kept losing compressors every single year until I piped in the last R-12 coil with an R-22 valve and installed a 30 HP Copeland in the condensing unit. No crane access - we hoisted the 30 HP Copeland up 30 feet on a ladder. <g>

Ahhhh . . . it was all great fun to make it work well.

That theater is still there - I wonder what they are running now?

PHM
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When I was a kid we had some old movie houses with Fricks.Water cooled seals, no black pipe r12,A/H D.C. Drive.By the time I was there it had a modern BAC evap. Condenser.I was told the install date was 1935

[coolperfect]

Yep,we had one well water only,changed coils tthere.Had another one that had well water to the AH and to the condensers of two Chrysler radial condensing units.We had a computer room with two Chrysler Radial chillers.I was told one of the first rooms built in the 1950's One chiller blow the cooler tubes,lost the comp,I did everything except putting in the tubes,The cooler had to be disconnected and turned 90 deg,there was not enough room between the wall and the cooler for the tubing