The recent posting of a question about a commercial chiller got me to thinking (always dangerous). I know they frequently use water chillers for airconditioning in commercial applications, but rarely in residential. I am aware that residential chillers exist (unico makes one) but you rarely hear about them and they don’t seem to have caught on. What is it that makes these systems good for commercial but not for residential? What are their benefits to commercial jobs? What are their downsides for residential?
John
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Replies
They're more expensive, take up more room, require more maintenance. Also, they generally tend to leak and/or produce a mist of water that could damage surrounding structures.
OTOH, I once kept our nearly-dead AC working through a several-day heat wave by setting up a water spray to hit the condenser. Had it gone on longer I would have installed a sprinkler control valve to make the water go on and off automatically.
Made a remarkable difference in the cooling capacity of the unit. (Compressor was about shot.)
"They're more expensive, take up more room, require more maintenance"
If that is true, why do commercial buildings use them? Not disagreeing (I have no knowledge of them), just questioning.
John
Because operating efficiency is much better.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Other reasons for use in commercial.More cooled space vs space to discharge hot air in the atmospher.Maintance men on staff to monitor and maintane equipment.More able and willing to invest the upfront cost.But you will still find a large number of air to air AC units that operate similar to residential units. One and two story standalong builings and strip malls..
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
"Made a remarkable difference in the cooling capacity of the unit. "I remember advertisements in the 1970s that offered a system which collected condensate and then misted it on the condenser coil. It supposedly increased efficiency by 50%.
Virtually all window ACs do that, I believe.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
"..more expensive, take up more room, require more maintenance..."
None of which are true.
Properly selected, designed and operated, chillers (and chilled water systems) are less expensive (on a per ton basis) for the owner topurchase, more efficient to operate(kw/ton) and require far less maintenance than distrubuted DX systems.
Yeah, but for your standard home install my statements hold.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
A "standard home install" vs a commmercial chiller system?
The only valid comparison between the two types of systems would be done at a capacity at which both are prevalent and are viable options. There is no such beast as a chiller "standard home install".
Comparing a DX system and chiller system at practically any tonnage at which they both exist, and the chiller system will exhibit none of the features or qualities that you guessed at (or made up).
The original question was why aren't they used in residential installations. That's the question I was answering.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Better control over discharge temps, and the ability to move a large number of btu's through small pipes over long distances.
I think your replies here may be (maybe, not sure) confusing cooling towers with water chillers.
Are you asking about a system where water loops around to airhandlers in the house and the transfer path is as follows:
1) heat in house to water in airhandler
2) Water from airhandler out to condenser outside
3) heat in water to freon in condensor
4) heat in freon to air outside house
Yes, I am talking about chillers (as you described), not cooling towers.
John
perhaps this clarification will draw out some new responses.
I suppose that the benefit for chillers and air handlers comes about when you have multiple zones widely dispersed? This is just speculation on my part.
Chilled water can be effectively/efficiently pumped over a greater distance than freon, and can be more easily "zoned". Plus water-air heat exchangers are cheaper and less high-tech than freon-air evaporators.OTOH, every time you change media you lose some efficiency, plus you add the extra complexity of water-circulating pumps, antifreeze, etc.There are residential split systems that employ chilled water. Mainly for zoned systems and those where the compressor/condenser must be located some distance from the cooled structure.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
This really should be directed to the OP.
I was just jumping in to see if he was getting the info he was looking for.
Right.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Yes, thanks to all who posted.
John
"There are residential split systems that employ chilled water>"
Such as? I have never heard of such. Who makes a split system that is based on chilled water? If it uses chilled water for cooling, what is "split"?
By "split" I mean having the compressor/condenser in one package and the air heat exchanger in another, connected by piping. I don't know any brands/models, but they've been mentioned here before.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Multiaqua makes a split system that uses a water chiller.
John
"..suppose that the benefit for chillers and air handlers comes about when you have multiple zones widely dispersed?"
One of the greatest benefits is the flexibility (for the designer) to select an air handler with the cooling coil required to comfortably accomodate a much large portion of ventilation (outside air) than is possible with all but the very best DX (direct expansion) based systems. Aaon, might arguably be considered the "best" in light commercial (12.5 to 30 tons) because they offer a 6-row evaporator coil that gets close to the performance of a decent chilled water coil. Zoning commecial systems into various zones is easily accomplished in either type of system.
Capacity control with a chilled water system, depending on the specifics and design, is almost infinite, while with DX systems, even very large ones, is only in discrete chunks or accomplished by wasting or bypassing a portion of the work in a "hot gas bypass" configuration.
The ability of transport and the relative cost of operation have already been covered.
Another great benefit with chilled water systems, is the ability to utilize thermal (or ice) storage for "peak shaving" type of energy savings.
Thanks for the answers. Are you at all familiar with the smaller units on the market (multiaqua and unico are the two I have seen). Sometime in the next 3-5 years I will be considering central air for my home, and was just curious about the chillers. Is there a downside to them for residential?
John
No, I can't say that I am very familiar with those chillers.
While I can see no real downside to residential use, I can see no real upside either.
All, or at least most, of the benefits previously discussed, will not exist for a residential sized chiller. The very high efficiencies acheivable with a centrifugal chiller and variable primary pumping are beyond the needs of most small commercial building, much less a single family home.
It will (almost certainly) be air cooled, single stage, single compressor. This will make it very similar in efficiency and capacity control as a standard ACCU (air cooled condesning unit, aka air conditioner). You have two fluids to contend with, water and refrigerant, so you would have two "systems" and would require an additional circulation pump and some extra minor controls.
IF you intended to zone your house with fan coil units or IF you were going to introduce a large amount of outside air and wanted excellent dehumidification (and had the ability or access to someone to select and obtain the right coil(s)), then you might find some benefit with a chiller/air handler.
I wouldn't do it in my house.
Chillers usually use a cooling tower ... rarely a condenser.
agreed
however, home units that use a chilled water loop, while rare, usually do not have a cooling tower.
ALL compressor based chillers use a condenser and an evaporator. Some chiller condensers are water cooled, some are air cooled.
Benefits for commercial include: easier to zone, more precise control possible especially with proportional controls, all of the refrigerant is in a machinery room rather than piped throughout a building, oil management is much simpler with a chiller, greater efficiency on a large scale. On a truly large building there would be thousands of additional refrigerant in piping in an occupied space (think of the potential for leaks and the EPA). Commercial buildings often need air conditioning when the outdoor air temps are in the 40's and 50's. If one were to run a residential type unit at these temps it would flood back and take the valves out of the compressor.
Downsides for residential: fewer people have sufficient experience to be truly proficient, residential is usually a single zone so there is a small loss in efficiency due to the double exchange of heat, upfront cost since there will need to be an additional hydronic system installed (pump, fill valve, expansion tank, etc).
A chiller can have either an air-cooled condenser or a water-cooled condenser. Water-cooled condensers are often connected to a cooling tower. Cooling towers require a great deal more maintenance.
I appreciate the thorough answer. Thanks.
John
I think Dan H said it right.
Chillers used in commercial because you often have to deliver that cool energy to many remote locations that can't use direct expansion (DX ... typical A/C) cooling systems. Rather than pump refrigerant (Freon) everywhere, and the associated problems maintaining such a system, the chiller acts as the go between between the air handling unit (chilled water coil) and the cooling tower (water cooled heat discharge system).
Chillers can be more efficient ... they just ain't for residences (at least normal size ones ... can't always build like Bill Gates).
i only know about these because i purchased a building with one... kinda like i know about elevators...
mine is a 4 pipe system... which means you can have heat and ac at the same time...
2 pipes for chilled water and 2 for heated...
pretty simple system... air handlers at each office... each with 2 coils and a blower and 2 valves... the thermostat in each office only operates the valves so calling for cool opens the chilled water valve and the the same for the heat ect...
chiller has a water tower... but like has been posted all the freon in in the chiller unit... transfers the "cold" to the water which is circulated by a pump thruout the building...
heat side has a boiler ... same deal...
for a large home i could see it work... with alot of zones... i think my gas & electric bills are low considering the size of the building... so even being close to 40yrs old... it still seems to work well...
lots of coils to keep clean... lots of valves... lots of blower motors and lots of belts and bearings... but... none of it is hard to service...
p