View Full Version : room independent heating and cooling
08-31-2009, 03:22 PM
I am not a HVAC guy, and have no knowledge of this stuff other than that it works. But I was thinking to myself - if they have water heaters that can heat your water at the point of delivery, why not a heating and cooling system that uses the existing duct work to deliver the air and then heats or cools it at the point of delivery? Does such a system exist? I tried googling it, but don't even know what to call such a thing. Zone control HVAC provided some answers, but not specifically what I was looking for. Something like those register boosters, the ones that cost around $50 and help boost your heating or cooling at the register. But less a boost and more a complete system. Does that make sense, and has it been done? Thanks for hearing me out and not calling me a fool for my lack of knowledge.
08-31-2009, 03:29 PM
Sounds cost prohibitive. Probably have to have a chiller & boiler to do it, a water coil at each room. Also would require a condensate drain at each coil. Most residential blowers couldn't handle the static pressure of all the coils. Even in commercial not done. Closest thing would be a fan coil in each room with the chilled & hot water serving it. Or VAV with a hot water coil in the VAV box but still the cool air is coming from a RTU or big air handler.
There's VRV like the City Multi with an air handler on the wall of each room and refrigerant going to it from the outdoor unit. Can heat & cool independent of each other. Also pricey!!
08-31-2009, 05:16 PM
There are a few ways to have independent temperature control on a room-by-room basis. Unfortunately none of them are cheap.
How cold does it get in your climate and will you be wanting to run heat and AC in different rooms at the same time?
@BaldLoonie: Citi Multi with simultaneous heat + cool requires three phase power. :(
08-31-2009, 05:24 PM
Look into mini split systems. They are close to what you asked for except no ducts.
08-31-2009, 07:37 PM
Does any of the Multi's competitors work on single phase? What did Trethewey put in the TOH house last year? Maybe it was just a multiple evap mini not a VRV.
08-31-2009, 10:28 PM
You might check into Daikin, they have a single phase multi indoor systems. Since the outdoor unit uses an inverter to control the speed of the compressor it only runs at the capacity that is needed based on the load. There are many indoor units available, ducted, ductless and cassettes that can be used either with or without ducts. VRV-S is the name of the system and up to 8 indoor units can be connected to one outdoor unit. There are some real advantages to this system; soft starts, low ambient cooling and very good heat pump performance.
Here is a link to the company site
Here is a link to the product card
Also Fujitsu has a multi-zone mini-split system. They also have a similar product but it does not perform quite as well as the Daikin; however there quite a difference in unit prices
08-31-2009, 10:56 PM
Both Citi Multi S series and the Daikin equivalent VRV-S series will run on single phase power. However, neither S or VRV-S can provide simultaneous heat and cool from the same outdoor unit. Simultaneous heat and cool is only offered on the Mitsubishi Citi Multi R2/WR2 and Daikin REYQ/RWEYQ series. All of these require three phase power.
08-31-2009, 11:23 PM
mini split hands down. would go with a sanyo or mitsubishi. i havent had much luck with fujitsus.
09-01-2009, 03:02 PM
Thanks for all the responses. As I said, I know nothing about how this stuff works, it was just a postulation on an idea / wondering what was already out there. I didn't even know how to phrase the question in a search engine environment.
Well, my thought was not to heat or cool rooms separately, but simply to put all the heat or cooling (depending on the season; I live in Utah and it gets relatively hot and also relatively cold, but not extremely so of either) to best use in the rooms that were being occupied and leave the others to themselves. Of course, this also relates to the quality (or lack there-of) of my internal and structural insulation, but that is a whole different story.
My theory was simply that heating or cooling an entire home, even a fairly small one like my post WW2 up and down, is not as effective as just heating or cooling individual rooms being used. My wife always complains that the kitchen is too hot (and too small, but that is another forum), and I am always annoyed that the downstairs is freezing when the upstairs is just right for her.
Anyway, as I said, it was a question on a theory. Thanks for the info.
09-01-2009, 04:28 PM
My vote goes for mini splits as well - check out all the manufacturers (Daiken, Mitsu, Sanyo, LG, etc) and go with whatever fits your application the best.
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