DIY Chiller Evaporator Question

[MeuserReef]

Im in the process of upgrading the Evaporator coil on my DIY (window unit) chiller and have a question regarding the direction I should go with respects to the type of design that will be used.

OPTION #1
Basically re-create what I have now, which is a PVC tube that water is pumped through. The heat exchanger is made from Titanium, but only has 10-12" of 1/2" OD tubing in contact with the water.

I "shot from the hip" with this design and ended up undersizing the evaporator coil. Option #1 would basically involve making a bigger PVC "barrel" that would allow approx 48" if 1/2" OD tubing, thereby enlarging the evap size

The advantage to this design is the ability to regulate the water flow (heat load) across the coil.

OPTION #2
The other option is to basically eliminate the barrel and go with a 48" coil that would drop into the sump. There would be an increase of coil contact, however I would no longer be able to control the heat load (flow rate) across the coil.

Option #2 affords a much less comlicated plumbing layout which helps with my limited space, but Option #1 affords a more controllable system. Is the gain of space worth the loss of heat load control?

Any thoughts?

[H20ENG]

By heat load control, do you mean the heat load on the refrigeration system? With a small system like a window unit, you dont want to overload it. They need some cool refrigerant passing through to help cool the compressor.

Any way to partition off the sump with temporary baffles to semi adjust the flow to the coil?

What BTUh rating does the unit have?

[not_sponsored]

If you can run multiple smaller titanium tubes through the larger PVC that would work better and be more compact I think.

[MeuserReef]

Originally posted by H20ENG
By heat load control, do you mean the heat load on the refrigeration system? With a small system like a window unit, you dont want to overload it. They need some cool refrigerant passing through to help cool the compressor.

Any way to partition off the sump with temporary baffles to semi adjust the flow to the coil?

What BTUh rating does the unit have?

I thought about the sump partition and I think this might be my answer. Perhaps even a slim acrylic box to seperate the water that is brought in contact with the coil from the rest of the water in the sump.

The unit runs on R22 and is rated @ 5150 BTU. In order to keep the compressor cooled, Im guessing that I should be keeping the evap coil temp down below, say 65-70° (112-122 psig)? The compressor should be able to handle "medium temp" refrigerant.

not_sponsored, because of the expensive compression fittings I am forced to use to transition from copper to SS, I would like to keep the evaporator coil limited to one single piece of tubing.

[H20ENG]

Med temp is fine. You can be sure those little AC units are overworked in their normal application

[MeuserReef]

Yeah... and not to mention the fact that they can be easily replaced cheap ($90 for the unit I used).

Nice website BTW Chris..

[H20ENG]

Thank you sir, yours as well

I also see them with digital thermostats now too.

If you use a Ranco to control your chiller, you could wrap the original temp sensor to the suction line, and have a constant readout of the suction line temp. Might as well use it if its there You could have the Tstat control a light to let you know its overtemp if you get real wily...

[BeanAnimal]

Yeah Chris... nice I never noticed that... You have a website now

I will put a link at the Bar and Grill

[H20ENG]

Thx Bean More to come...