Where to find small sized central A/C
We are building a new home in Vermont. The air conditioning debate is still going. I (my wife especially) would like a central air system. However, the needs of the house are very small. We have good solar shading, insulation etc. and with a Vermont climate a 9,000 btu/hr system would be more than enough. With a little poking around, I’ve come up empty. Doesn’t the government promote energy efficiency? Why are there so many sales on these massive 5 ton units, but the smallest unit I can find is 1.5 tons? Does anyone have any sources or alternative ideas? We want a central system to provide a uniform climate througout the house. Also, busting the humidity is the biggest advantage to our thinking. Ducting is obviously quite small. It seems that a 500 cfm air handler with 3/4 ton condenser would do the trick nicely. Where to buy?
Replies
I am not aware of any manufacturer that makes anything smaller than a 1.5 ton split system- must not be a demand for it.
You may want to look at some of the mini-split systems. There are systems that allow multiple evaporators connected to a single condenser.
Sounds like a good place for a vertical PTAC unit. It's like a window ac but it pulls outside air in through a grille, runs it over a coil and exhausts it back out through a smaller grill to throw it clear of the intake. It drys and cools and the heat pump models warm as well with a lectric strip for aux heat. You just want the cooling one up there since you need more BTUs than this can comfortably put out. good for small spots that need more drying than cooling, commonly used in hotel rooms. YOu can duct the supplies to give it better air distribution. Don't expect robust energy efficiency out of one of these but you should be able to get the whole set up for $1,500.
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"You cannot work hard enough to make up for a sloppy estimate."
Many motel rooms in the Caribbean islands have small split sysytems that work welll and are very qquiet.
I've looked at the mini-split systems. Do I understand this system to also be fixed? If so, it just won't provide the whole house with the uniform climate we're used to with central air. Can this system be ducted? I would also think that a high velocity type system could work for our load if they were available in smaller sizes.
There are numerous options depending on how much you are willing to pay and how much efficiency and comfort you need to have. Ducted PTAC is cheapest but you only get two or three supply ducts and one return and it's somewhat noisy and not all that energy efficient but it costs only about $1,500 and can generally be installed by an electrician and a carpenter. Seems perfect for AC only at a vacation house in Vermont. I'm putting a heat pump model in my wifes dance studio here in NC. Noisy but the tunes are cranked up to 11 whenever she's using the space which is a few hours a day.Mini splits can be amazingly efficient and fairly quiet but they have the return and supply in the same unit and they are more expensive depending on your source of supply and generally need to be installed by a licensed HVAC contractor.High Velocity mini duct systems are rather gourmet and out of the price range of my clientèle at least. If you can get one at a price you can afford it will do the job very well and at good efficiency.------------------
"You cannot work hard enough to make up for a sloppy estimate."
I'm surprised to be the first fellow looking for smaller central units. The HVAC folks for our previous home speced out a 4 ton unit (Connecticut) and I think the delta t was around 15 degrees. I installed a 1.5 ton unit and we had extremely comfortable air conditioning at a low cost. I know the electrical bills were less than others with similar size homes in the area. We would set the thermostat at 5-10 degrees below the outdoor temperature. The unit had good long cycles and really knocked the humidity out. My cooling load in Vermont would only be 8000 btu/hr with a delta T of 10 degrees. Being constrained by readily available duct sizes I can be sure of a very quiet operation if I could just find a 500 cfm air handler. What about those evaporators designed to go in existing central furnaces? Could something like that be paired with a circlator somehow?
I think this is really beyond my knowledge level. I can't seem to find a decent 15 SEER Variable speed AC under 2 tons and $8,000 installed. I'd like to beleive there is an affordable alternative out there but I don't know what it is short of the PTAC or a small Heat pump.Sorry not to have a more definative answer.M------------------
"You cannot work hard enough to make up for a sloppy estimate."
I also think you need to look at a mini split...
but... a few years ago we ended up with a truck load of 1ton mini split condensors...and none of the coil/blower/control inside part...
so we used standard indoor air handlers and used the 1ton half of the mini splits outside... we got em for about nothing so it was worth the effort...
look on ebay for "mini split" you'll be surprised how cheap you can get 1/2ton , 3/4ton and 1ton systems... if i was you i'd look at 2... think you can do 2 small units for under $1200 total... maybe less
p
http://www.firstco.com/products/spx_cooling_electric.asp
It is a package unit but is ductable.
ITs a start anyway.
(No affiliation with them, did buy from them in a prior life when I was a project manager for a mechanical company)