# Mini-splits



## krondor2 (May 28, 2007)

just for cooling for a total off grid solar, wind.

115v and 15 amps, one ton system

would you have one, less power to run than conventional AC and only cool the room you are in instead of the whole home.


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## wy_white_wolf (Oct 14, 2004)

Still 1725 watts per hour. That's a lot of dollars in solar or wind.

I'll find less expensive alternatives for off grid.


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## morrowsmowers (Jun 14, 2004)

Those split systems would have to be installed in each room and then turned off and on as needed -- could become very expensive depending on total rooms you have -- they do make split systems for multiple rooms but your energy usage will jump up as well.

Ken in Glassboro, NJ


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## Metcalf (Feb 15, 2007)

Why not invest the money in insulation, awnings, etc. You could even look into doing a ground tube cooling system for the money. In general its easier and cheaper to not need A/C in the first place. 

What are the problems your having now? late in the day over heating, high humidity, slow air changeover in the house at night. etc???


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## SolarGary (Sep 8, 2005)

krondor2 said:


> just for cooling for a total off grid solar, wind.
> 
> 115v and 15 amps, one ton system
> 
> would you have one, less power to run than conventional AC and only cool the room you are in instead of the whole home.


What kind of climate do you live in?

Gary


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## krondor2 (May 28, 2007)

not really building now just thinking out loud and trying to find options for cooling for off grid situation. live in the south. thanks for any insight.


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## SolarGary (Sep 8, 2005)

krondor2 said:


> not really building now just thinking out loud and trying to find options for cooling for off grid situation. live in the south. thanks for any insight.


Hi,
If you are building a new home, I'd think first about minimizing the need for mechanical AC of any kind.

I'd have a look at the entry "The Energy Efficient House" -- its down this page a ways:
http://www.builditsolar.com/Projects/SolarHomes/guidesps.htm

This is an article by Richard Crume published in Solar Today -- it covers the techniques he used to minimize AC and heating use. I think its really well thought out, and it applies to southern climates (NC).

Gary


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## WisJim (Jan 14, 2004)

Insulation, shade and ventilation are cheaper in the long run than A/C systems.


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## Metcalf (Feb 15, 2007)

In a strongly insulated house and some insulated thermal mass on the floor you could use a ground loop geothermal exchange system to cool a house rather well off the grid. The only thing you would have to run would be a small DC pump to circulate the water. 

Basics. There are tubes laid in the concrete floor, then there are tubes laid outside deep enough in the ground to get a rather stable temp. Water is then circulated through the system. The ground is a rather constant at not more 50-60 degrees in most areas. This lets you cool your house for very little energy. Its not ideal...but it works rather well. 

Another important thing is being able to get the hot air out of your house when you need to. Attic fans, tall skinny windows that open at the top, etc....these all help get hot air out at night to get the temp down for the next day.


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## quietstar (Dec 11, 2002)

Mr.Metcalf..You don't provide your location, however I'm certain it is not in the hot,humid South. Your well meant suggestions will reduce the summer heat a bit at some cost, but do little to nothing about humidity. I'm shooting for reducing the required AC load so that smaller, High EER units will do the job well enough that ceiling fans may provide the required comfort level. Winter, however is a cakewalk using direct gain solar along with a small heatpump boost on extreme days...Glen


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## greg273 (Aug 5, 2003)

WisJim said:


> Insulation, shade and ventilation are cheaper in the long run than A/C systems.


 Especially if you live in Wisconsin.  Down here in the 'south', it gets warm. Real warm. At least the hottest month, August, is about done.
I just picked up the thread in Otherpower.com regarding 'ground temp cooling". I am leaning towards the water-filled variant, if I can figure out the neccesary amount of pipe to use.
Metcalf, have you built one of these systems?


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## Metcalf (Feb 15, 2007)

Sadly most of my knowledge has only been applied in the classroom. I have my BA in mechanical Engineering with an alternative energy focus. The technology is well proven. Most modern geothermal heat pumps use this technology for heating ( in reverse with a little compression ) and cooling.

This should get you started at least. If your going to install a system like this you might want to think about winter heating with it also. Most all of the expensive stuff is going to be installed already.

http://en.wikipedia.org/wiki/Geothermal_heat_pump


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## Severian (Oct 22, 2006)

quietstar said:


> Mr.Metcalf..You don't provide your location, however I'm certain it is not in the hot,humid South. Your well meant suggestions will reduce the summer heat a bit at some cost, but do little to nothing about humidity. I'm shooting for reducing the required AC load so that smaller, High EER units will do the job well enough that ceiling fans may provide the required comfort level. Winter, however is a cakewalk using direct gain solar along with a small heatpump boost on extreme days...Glen



Actually, if the ground chilled water is piped through a finned coil, with a small fan to blow air across it, you will remove humidity from the room, just like a regular air conditioner, well more like a window unit. Some of the factories i've worked at, as an hvac mechanic, used big chilled water systems for all their cooling. Each zone, or room, has it's own "box" with a finned coil & a fan in it.
A small geo thermal system would work, but not sure how well on an off grid app.


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## Jim-mi (May 15, 2002)

Yup, . . . An off grid system would need to be kinda large ($$$$$) to handle those pumps that would be running almost constantly.


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