Residential Chiller

Paul S_3

Customer of mine has a chilled water system in his home. Home is about 12,000 sq ft. They have a small cooling tower outside and a packaged refrigeration system inside mechanical room with refrigerant to water heat exchanger. They have 11 3ton chilled water fan coils. What manufactures are there for system replacement. I was thinking of a air cooled packaged chiller outdoor unit? Or maybe standard condensers with a refrigerant to water heat exchanger inside mechanical room. Any help is appreciated. Thank you

mattmia2

I have seen systems where they use a brazed plate head exchanger as an evaporator but that was a relatively small system. If you change it to an air cooled condenser you need a condenser that can modulate to the load. Maybe some number of staged condenser.

pecmsg

Unless that cooling tower is serviced and chemically treated, I would scrap the entire thing. Legionnaires disease.

Any air to water system would be fine.

EBEBRATT-Ed

I would use an air cooled chiller and scrap the water tower.

One important thing is buy the chiller with a REMOTE chiller barrel (heat exchanger). If you do that you will pipe refrigeration from the new chiller outside to the new HX inside. Don't try and rig up standard condensing units with your own HX it will become a controls nightmare

By doing this you will avoid having any issues with having to drain the chiller system water in the winter or using glycol and have no issues with freezing problems.

Carrier, Trane, York and there are others can supply this

ratio

Mitsubishi/Trane has several air to water models in the City Multi line of VRF units.

Paul S_3

Thanks for all the insight. I was looking into the multi aqua air cooled chillers. Using a 10 ton & 5 ton or (3) 5 tons. Refrigeration would be self contained outside. I would then have to run properly size chilled water piping to mechanical room and install a pump. The installation manuals show a storage tank/buffer tank. Is the tank absolutely necessary? Maybe to eliminate short cycling on mild days

pecmsg

15-Tons of cooling in a residence?

DCContrarian

https://forum.heatinghelp.com/discussion/comment/1817067#Comment_1817067

Yeah, I'm surprised no one has mentioned doing a Manual J rather than just matching the installed capacity. 12,000 SF is big but not that big.

DCContrarian

https://forum.heatinghelp.com/discussion/comment/1817040#Comment_1817040

Yep, a compressor is going to have a minimum output and a minimum recommended run time, the buffer tank is sized to absorb at least that amount.

Beyond that, the buffer tank is not your friend. You want the water as cold as you can get it, anything that mixes the water is robbing performance and efficiency.

ethicalpaul

https://forum.heatinghelp.com/discussion/comment/1817067#Comment_1817067

There are residences, and then there are residences

GGross

Maybe I missed something but isn't the installed equipment capacity 33 tons? 11each 3 ton fan coils? so 10-15 tons is well below equipment capacity? With a bunch of internal loads, and glass I wouldn't be surprised to have peak loads close to that 15 ton point, but you definitely want to size condensing units that have lower minimum outputs because the average load likely won't even be half of that. The more I type the more it just makes sense to run the manual J, surely someone has prints and historic data for a 12,000 square foot home? The owner knows whether they plan to pack people in there or not. In my area the owners always want to size for the absolute worst case scenario and then they never actually see those conditions.

mattmia2

A great thing about a chillwater coil is you can adjust flow and airflow to match the load. Not so much with DX.

pecmsg

https://forum.heatinghelp.com/discussion/comment/1817089#Comment_1817089

even out here in the Hamptons I can’t think of maybe a hand full of 15-Ton homes.

EBEBRATT-Ed

@Paul S_3

If you buy an air-cooled chiller and pipe the chilled water indoors you going to be faced with filling and draining it every spring and fall and maybe blowing the HX in the chiller out with air to prevent freezing. Or use glycol.

Both are a PITA and there is always the risk of a freeze up. JMHO. I would put the chiller barrell indoors.

pecmsg

keep the chilled water inside.
this is the prefect example of weather. Shortly nighttime temperatures will be below freezing. In your day or two it could be 70+. Not worth a headache.

Keep the chilled water inside

DCContrarian

There was a thread recently on GBA where a guy said he moved the heat exchanger from his Arctic indoors. It involved pumping down the refrigerant, cutting and lengthening the refrigerant lines and then recharging and adding a bit for the longer lines. But there are a lot of advantages to keeping all of the water in the house. For someone who works with HVAC that's all in a day's work. 
See:  post #44. 

https://www.greenbuildingadvisor.com/question/im-looking-for-user-experience-with-arctic-heat-pumps

Arctic goes up to five tons.

EBEBRATT-Ed

Why go through the effort of taking the charge out and relocating the HX?

All your doing is voiding the warranty

They make and sell chillers with remote barrels. I have installed many that way. @pecmsg is correct. Why fill and drain in the shoulder seasons?

It was 70 deg in my area today. We usually draing everything outdoors no later than 11/15 because usually by that time it's getting down around 18-20 at night. 32 may be freezing but you need some TD to make it freeze.

Paul S_3

@EBEBRATT-Ed what manufactureshave remote barrels. My suppliers are providing packaged outdoor chillers. These are not common in my area.(North east). I would do a load calc once we find equipment

jumper

Ideally I'd go other way. Chiller in heated space and remote air cooled condenser outside. No glycol nor winter draining.

pecmsg

https://forum.heatinghelp.com/discussion/comment/1817205#Comment_1817205

Artic heat pump is one

EBEBRATT-Ed

Almost every chiller MFG can provide the option of a remote barrel