[alpha480v]

Yes,we use the ac alot at our house.This summer seems more hot and humid then previous summers in my area.And,after having worked on ac,and refrigeration equipment all day,you better believe that I will come home to an air conditioned house!

[Sparaxis]

I have a built-in air conditioner--the Pacific summer marine layer. This is how it looks from my balcony as it keeps the temps nice and cool. Actually, too cool sometimes. I wish it came with a thermostat.

[pea-jay]

I don't have air conditioning, but I do have an evaporative cooler. For those of you that are not familiar with them, they utilize the power of evaporation of water to lower the temperature. They utilize 10-25% the electricity of an AC unit. They work pretty well until the dewpoint creeps above 60 degrees. With a dewpoint of 65 they suck and at 70 they worthless. Right now the dewpoint is at 63. Yuck.

[LadyRuby]

No AC, a couple of fans, and a cool downstairs that's helpful in a pinch.

[Grimnir]

I've discovered that a window fan and (in a pinch) a desk fan pointed at you can do wonders. I have a window AC unit in the bedroom, but I've only turned it on a couple times on especially high heat/high humidity nights when I just couldn't sleep. It doesn't have to run very often if I keep the bedroom door shut.

[navyswan]

AC is a must in the South!! It is too hot not to have one. For example, right now it is 5am and it is 75 degrees outside with a dewpoint of 74 degrees. And no, it isn't raining. It is just that darn humid. It is worse in the deep south where I am from. In the summer, it rarely gets below 80 degrees in the summer. I am not talking about the high temp, the low temp rarely goes below 80 during the summer months in the deep south.

I remember a few years ago I was traveling and left home at 3am, it was 85 degrees outside at 3am. And the kicker, it was late October!! That's southern Alabama for you. So i don't feel bad about using my AC.

[Simpson]

I need thoughts on Carrier window-mounted heat pumps.
Experience with them, maintaining them, efficiency, etc.

Also, does anybody else make one?

I am not interested in the mini-two-piece types; their small size makes them difficult to maintain; is the same true of the window units?

The Carriers that I found online are Performance Series (XQ Series), such as: XQB101D, XQB123D, XQB153D 7 XQB183D

[BabyPeanut]

How does a heat pump work? (link)
...skip...
Imagine that you took an air conditioner and flipped it around so that the hot coils were on the inside and the cold coils were on the outside. Then you would have a heater. It turns out that this heater works extremely well. Rather than burning a fuel, what it is doing is "moving heat."
...snip...

Not burning a fuel? Well if it's nuclear, hydro, solar, wind, etc. electricity it would be but right now most electricity comes from burning coal.

As for the heat pump, trouble is that if there's very little heat outside relative to inside you are not going to be able to move much heat in. Unless you live in a very warm climate a heat pump will only work on the "not so bad" days. You will need a second source of heat but this is not really a problem and it keeps the usage of a furnace down. The furnace will be needed for fewer days out of the year.

One issue with a window unit would be that you lose warm air out of any gaps or cracks around the unit. Make sure everything is properly sealed.

Do window units have automatic cut-off? A "dual-fuel" furnace (also called a heat pump with a "fossil fuel" kit or option) will sense the temperature and switch to the furnace when it gets too cold for the heat pump.

I think most heat pumps use electric resistance coils (like an electric stove burner) as the secondary heat source and they are the worst, most wasteful, expensive form of heat. Trying together a heat pump and a gas, propane or oil furnace is a much better deal.

[BabyPeanut]

This might be cheaper:

Maytag Sunpentown WA-1010H (NOT the WA-1010M as it has no heat pump option)

The addition of the heating function allows you to use this unit year-round. Cool in the summer and heat in the winter! The design of this portable room air conditioner utilizes the compressor to provide heating (this system is called a heat pump) so heat is efficiently generated. (link)

http://www.priceground.com/su10poaircow.html

Retail Price: $565.00 - PreHoliday Sale: $366.00

I'm not sure if that price includes the window venting kit or not.

You should do your own research.

[oilfreeandhappy]

I heard a talk by a "green" HVAC contractor about 5 years ago on building extremely airtight homes. To get the required number of air exchanges for healthy breathing, an air-to-air heat exchanger was employed. According to this gentleman, this is the same technology that large hotels use to exchange their air. And he mentioned that the exchangers were very efficient, and saved a lot on energy costs.

Since then, I've heard very little about this. Is this a good way to go?

[Aedo]

This makes a lot of sense - to keep a house "fresh" and comfortable you need to continuously exchange the air. If there is a significant difference between inside and outside air temperatures this continual refreshing is then expensive.

Like you I saw this idea (about 15years ago in the UK) which used heat exchangers under the eaves but I haven't seen it since. I suspect there is no specific manufacturer of these heat exchangers and that you would have ones custom made to suit the building - if I didn't live in such a temperate climate (inch gaps under the doors simply improve the air circulation!) I would look to employ this idea.

[Frank]

From what I understand, heat exchangers are now required in new homes in Canada - not sure of the details but friends have told me that is the case.

[SmokinJuan]

I thought about laying some lengthy ductwork (concrete?) outside underground (about 5' deep) to bring outside air into the house while raising the air temp towards 54 degrees.

The problems:
Cost - Would it be worthwhile to dig a 5' deep 100' long(?) trench full of reinforced waterproof concrete ductwork?
Filtering - A dead mouse in the duct would stink. Needs grates, filters, cleanout portals.
Leaking - Moisture in the duct would stink.
Temperature saturation - If run long enough the earth temp would saturate making the whole thing useless.

How often/long should air be exchanged? I guess run time would be determined by cubic feet of the house and airfolw capacity through the duct/blower. A thought on "how often" dictates sensors in the house to monitor CO2 and cycle accordingly OR cycle periodically based on cubic feet of the house, number of air braething creatures inside, outside air temp, are the windows open, is anyone home, etc.

[oilfreeandhappy]

Laughs Last,
Thanks for the link. I do recall that name now that I read the article - heat recovery ventilator. Of course, the big savings here is that a house can be built as airtight as possible. I imagine the fan has to be running all the time.
Jim
http://home.comcast.net/~oil_free_and_happy/

[strider3700]

HRV's are not ultra common but you can pick one up at any big box store
http://tinyurl.com/cbegz

If your home is plumbed for them then they are a great addition. My home has no ducts making them a difficult install

[rockdoc123]

From what I understand, heat exchangers are now required in new homes in Canada - not sure of the details but friends have told me that is the case.

Not sure if they are but our current home is about 2 years old now and has a heat exchange unit. I had the house tested for energy efficiency and apparently it is as tight as "a bulls ass in fly season". The recommendation from the furnace guys I had out installing some programable thermostats and fiddling around with the insulation around the cold air returns is that in the winter you need to run them once a week for a couple of hours to get complete recycling. I know people who have them turned on continuously in the winter but I just don't see the need. I actually haven't noticed any wierd deterioration in air quality...but that is likely a hard thing to notice. When I think how often a door gets opened each day....get the paper....go to the garage....let the mutt out..etc. I actually wonder how much the air needs changing. That being said greater minds than mine came up with this so I'm with the program.

[oilfreeandhappy]

My current home isn't tight enough to warrant the installation of an HRV. When I build my small air-tight retirement home with PV roof shingles, I'll get one of these!
Jim
http://home.comcast.net/~oil_free_and_happy/

[thegrq]

Here's a conversation that I had with Dave Braden, a builder who makes super energy efficient homes (the link will take you to the download page for the mp3 file, the actual interview starts at around the 6:30 min mark).

He said that his current house design has a heating/cooling bill of about $50/year (and that's in a cold part of Canada) and his next design won't even need a furnace. He does this by making his homes completely gas tight, and then using an air exchanger set on a timer to get stale air out and fresh air in.

[thegrq]

Whoops, I just made a post about this here in the forums. I spoke to somebody who builds super high efficieny homes because his homes are all gas tight. His energy bill is $50/year in Canada. He has an air exchanger set on a timer so it only exchanges air when people are in the house. For his next home he will build it without a furnace at all.

[WisJim]

I thought about laying some lengthy ductwork (concrete?) outside underground (about 5' deep) to bring outside air into the house while raising the air temp towards 54 degrees.

The problems:
Cost - Would it be worthwhile to dig a 5' deep 100' long(?) trench full of reinforced waterproof concrete ductwork?

More like 8 feet deep around here (Wisconsin). Also, mold can be a big problem. What I have heard of being done is 3 to 4 foot diameter tubing with drain holes to let out moisture build up, 8 feet or deeper, and hundreds of feet long. I have considered it, and have friends who tried it, but they have all abandoned this system.

Back to air-to-air heat exchangers. We go to lots of "tours of homes" to look at new houses and see if anyone is doing anything worth copying (almost never anything remotely sensible or energy efficient), and most new homes have air-to-air heat exchangers in them. They are often tied into the kitchen or bathroom exhaust fans, so they run at the same times as the exhaust fans, and/or controlled by humidistats, to run when humidity increases. They are quite common now, and readily available from a number of commercial sources, through almost any good Heating and Ventilation contractor.