Feasibility of Pre-Cooling Freon with Water Heat Exchanger 6

[johnatthelake]

In "residential water-cooled air conditioning" thread403-200396: gepman states "There are also one pass through water-cooled systems (sometimes used where there is a large source of surface water such as a river, lake, or ocean)."

What are the pros/cons and feasibility of pre-cooling the freon in a water source heat exchanger between the air handler and a non-modified condensing unit if there is plenty of water from a lake available?

What sources of information are available?

 

[blutfort]

As long as proper piping practices are followed and the water to refrigerant HX is properly selected there should be few mechanical reasons. There might be several environmental ones.

In your piping watch out for oil traps; make certain that oil can return to the compressor; make certain that liquid freon does not back flood the compressor.
Depending upon the relative temperatures there is a chance that all the freon could pool in the HX and there could be instances of suction pressure faults on start up.

Additionally you will want to have some sort of head pressure regulator going on. Either adjust flow through the HX or with a refrigerant flow device.

I have a similar design for my home where I use the swimming pool as a heat sink to recover the heat to keep the pool on the warm side.

 

[rmw]

I just gave away one and have one more to dispose of heat exchanger units manufactured about 30 years ago (these have the Lennox brand name on them, but they are just branded by Lennox) water cooled heat exchangers that mounted between the compressor and the condenser on home AC units. The water that absorbed the compressor heat was circulated from the domestic hot water heater and it worked well...., well, until the hot water heater and the entire circulation loop became saturated with 180F water at which time it shut off (didn't circulate when the condenser came on-the gas just passed through it.) It took 3-4 cycles of the AC unit before the domestic hot water was so hot it was dangerous. Unless showers/baths/diswashing was actually in progress, the A/C quickly over ran the ability of the system to store the heat.

So conceptually, it worked wonderfully-it did what it was designed to do. In reality, it didn't work well at all. I helped a buddy install one and after seeing his results (we both had young kids too and the wife balked-and I really mean balked at having 180F water coming out of the HW taps in the house) I didn't even install my two-I had 2 A/C units in my home hence the need to dispose of these two units now some 30 years and one house move later.

I live in a part of the country where when we need A/C (almost 8 months of the year) we could also use some means of chilling the pool water, not heating it, so that was not a candidate for a heat sink. Ground water would have been a candidate, but then in my day job I do heat transfer and cleanliness and fouling are something that give me great pause with respect to using raw water of any type in a Hx this small.

Imok2, I have a hard time equating residential pool chemical maintenance with cooling tower water maintenance. I see cooling tower water as much more diverse, demanding and complicated. However, if some system were to come onto the market that was technically viable, I see a real niche for some company to go around and do the service like some pool service companies do. BTW, and as an aside, I won't have a pool and that is one battle I have always won with the wife and kids. I kept up one as a young man at a youth camp and I never wanted any more of that.

rmw

 

[my3boys]

With the advent of new swimming pool 2 speed pump requirements, the pool pumps will essentially run 24 hours. Given this new information, would the benefits of routing a circulation line to a water/freon pre-chiller be considered relatively free minus the initial capital cost? If so, how would a non-HVAC engineer like myself go about sizing a heat exchanger? Break - Does this additional heat sink then cause an automatic modification requirement to the expansion valve in a typical home ac system?

Thanks to all for the expert knowledge and insight in these threads. Most impressive group of contributors.

 

[philthetrainguy]

rmw,

Ok the freon temp into the exchangers is hot - too hot for home h/w. why not do it the other way round do the air first and then the water? Any thing wrong with that??

-Phil

 

[culks]

Going back to blutfort's swimming pool heat sink. Is it as straight forward as adding a refrigerant to water heat exchange into the home ac after the compressor or do you need additional control equipment e.g. flow control or over ride for the pool pump. What happens if the pool pump isn't running or at the start of the season when the water is very cold. Can this cause shock to the exchange and freeze the whole thing up? Do you need a special heat exchange due to the pool chemicals?

I wish I'd read rmw's post before I got the pool, I've ended up doing all the maintenance

 

[nuhvac]

My company builds what you are talking about, we call them ground source heat pumps. Also they are called "california loops" you can google either phrase and it should give you a mess of results and information. Probably more information than you need.