Author Topic: How to cool the home. (Read 6199 times)

Instinctz · « **on:** July 30, 2006, 07:55:45 PM »

I was just wondering how the majority of off grider's cooled down their home? With the high current pull from full sized AC units the 300ah seems a huge drain. Are window units a more feasable solution? My current home is a complete cool'ing waste where even if my AC is ran 24/7 it never gets much less the 15-20 degree's less than outside. Currently we have been see'ing nearly consistant 100+ degree's with in house temps between 77-84. Only getting down to 72-75 at night.

The AC unit probably consumes 80-90% of my electrical usage per month.. so it would be great to get that down some. Getting my small 20% electric use (Lights/Tv) down wouldnt be hard at all.

Anyways, how do ya guys go about coolin off?

AbyssUnderground · « **Reply #1 on:** July 30, 2006, 02:02:01 PM »

A cold shower? :-)

Instinctz · « **Reply #2 on:** July 30, 2006, 02:10:00 PM »

Hehe, yes it seems there are many different ways to go about it.

I do have to agree.. city slickers have gotten way to comfertable with all of that "easy power" readily availible, and yes I'm just as bad as any of'em.

Nando · « **Reply #3 on:** July 30, 2006, 02:26:47 PM »

First; You need to determine how good the insulation of the house is, specially the ceiling area.

Second: check to see if your air conditioner needs gas, working full time could be one reason, next the evaporator coil to see if is clogged (most of the time) they in the attic area .

Third: check the capacity of the air unit.

Fourth: check if the filters are clean and not clogged, filter replacement, including the attic filter if the evaporator unit has one.

Some have done the spray mist solution and it is to install roof sprayers to keep the roof barely moist (around 30 to 40 5 energy savings), though One needs to have a small controller to open and close the sprayers ( the sprayers work just a few seconds in several minutes )

Then start turning OFF equipment that heat the house and not needed.

Nando

dinges · « **Reply #4 on:** July 30, 2006, 02:58:31 PM »

Also, heat that doesn't get generated doesn't have to be removed.

A 250W PC that's continually on generates 250W of heat, continually. An incandescent bulb generates a lot of heat too. Switch to CFLs and notebooks (or switch off the PC when not in use) should reduce heat-production quite a bit. A double whammy: less electricity use of the appliance, and less energy used by the airconditioner for REMOVING the heat of that appliance.

Just something to keep in mind with airco.

willib · « **Reply #5 on:** July 30, 2006, 03:28:47 PM »

If you have a high water table , you could use that cool water to cool your house.

hiker · « **Reply #6 on:** July 30, 2006, 04:19:51 PM »

if you have plenty of water in your area -and pay one flat rate[no meters]..

seems to me -if you hook up a couple of car or truck radeaters to a hose and run your cold water throu those with a fan pushing the cold air out .then use the exit water for your lawn or garden..simple enough..

--the way you guys have been cooking down their i really dout if you have the water to spare-- cool summer here--dam near normal..last few summer were hot and dry..kinda nice to have a rainy cool summer for a change..every thing nice and green..okay im gone..

whatsnext · « **Reply #7 on:** July 30, 2006, 04:34:04 PM »

You might want to consider the window unit option. I have a giant city house with three seperate HVAC systems. Even though I have new 92% furnaces I kept the older compressors. Cooling only the room I'm in saves me a ton but it may not work for you if you need everything cool. You might also want to think about ceiling fans as I find they make things feel about 5 or 10 degrees cooler.

John..

Norm · « **Reply #8 on:** July 30, 2006, 05:37:23 PM »

What is the coldest you get about 12inches away

from the AC ? I'm having a similar problem ...

(2 window units)when I came back from shopping I had turned off the ACs ....thermostat read 85

in 10 minutes it had dropped to 83.....now 3hrs

later the sun is setting and it's finally got

down to 80 (87 then and 85 now outside. The coldest I can get is 67 a foot away from either

of the ACs filters are clean but they are both

about 8 years old and never been recharged.

My oldest and youngest are both schooled in

refrigeration and air conditioning....they work

as maintainence men and that is one of their jobs

.....I think I have a problem...LOL !

( :>) Norm.

willib · « **Reply #9 on:** July 30, 2006, 05:56:57 PM »

with no lawn to water

it would just go to waste , for me . and with a large part of the world without nice clean water , well you understand...

what i was thinking of before was using the groundwater as a heat sink , with lots of tubing or pipes in the ground , its nothing new , but if i had the land i would do something like that in a second..

stephent · « **Reply #10 on:** July 30, 2006, 06:00:17 PM »

The 15 to 20 deg difference is normal with most home sized AC units.

It's about all you can expect with any humidity level we have in a home.

Run a dehumidifier or two and the AC will have a lower latent heat load level (and you can feel this) to contend with and it will 'feel" cooler even if you raise the AC temp level to save a bit of electric. Even though AC units have a drain pan and a pipe going outside (hopefully!) to get rid of the water, they make a lousy dehumidifier (air speed going over coils is too high) and folks just breathing inside the home release a lot of moisture. as do dishwashers and stuff cooking on the stove--run these at night when the cooling load is lower or cook on the grill outside.

check to make sure the drain is free and there isn't much water standing in the evaporator "pan" area... small amount is normal less then 1/4 in with a proper drain.

Use a setback thermostat--your body temp falls slightly in sleep.

But plain and simple---AC and off grid or grid tied genny is going to be $$ and a lot of them for most normal folks. Not even trying to figure the cost of a solar panel + inverter capable of supporting a central AC unit. (mine 8.8KW + starting surge--even Bill Gates would say--WHAT?!!)

Seems there isn't any free lunch with using Air conditioning powered by anything--yet.

Hopefully within our lifetime we can look back and say "geez we were stupid not have seen the use of ------ to get power from".

Ungrounded Lightning Rod · « **Reply #11 on:** July 30, 2006, 06:02:08 PM »

Don't turn off the AC when you're only away for a few hours. There's a lot of heat capacity in the furniture in a room, and it takes a long time to bring it down - especially if the AC is working against a heat wave. Better to keep it cool in the first place. Not a lot more power use, and you get to be cool for a few hours that you'd have been hot just after arriving. (That IS what you're paying for, after all. Why save a few percent and lose half of what you bought?)

If you're going to be gone for a weekend or more, THEN shut it down.

Off grid in Tonopah · « **Reply #12 on:** July 30, 2006, 06:24:01 PM »

I live off grid in Tonopah AZ. Summer time temps are 110+ and to humid to run a evap. cooler during our monsoon. My first two years in my present home I used window units to cool my home and a 5500 watt Wheel House (brand name) gas 3600 rpm generator. I had converted the generator to run on propane and had a 500 gal. Tank to run on. Believe it or not I ran this for up to 2000 hours before it gave up the ghost. I ran the window units so I could start them up in staggered fashion so the generator could handle the starting current. Worked fine for all but the hottest days. It allowed us to spot cool the bedrooms at night and the living area during the days. I have a central unit now and a 15 KW diesel it runs about 18 hours a day June,July and August. Rest of the year I use 1100 watts of solar and evap cooler and only need to run the gen. about 3 hours a week for water pumping and running the washer for my lovely and very understanding wife. I hope to add a wind turbine this year to help the solar out. Feel free to ask anything else if I can help. I've been off the grid now 5 years and pretty much got all the bugs work out for me

Bob

willib · « **Reply #13 on:** July 30, 2006, 08:10:40 PM »

i didnt know there was a monsoon season in Arizona .

i would like to hear more about your evap cooler ?

how large is it?

how good does it work?

Countryboy · « **Reply #14 on:** July 30, 2006, 09:59:41 PM »

Folks, you HAVE to think outside the box. Using electricity for cooling is NOT thinking outside the box.

2000 years ago, the Persians discovered Central Air Conditioning, while living in a desert with no electricity. They could cool their homes by about 15 degrees Celcius (27 F).

The subsoil stays about 55-56 F year round below the frost line. The Persians dug a long tunnel in the ground, usually 6-10 miles long. This tunnel was primarily used to bring water from a distant well to a community. The Persians used the cool air in the tunnel to cool their homes.

There is no reason folks can't run some farm drainage tile around their home, and have a small fan blowing air through the tile as a cool air source for their home. It'll cut down on your heating needs in winter too.

Get a basement under your home for the same reasons. Below ground is cooler than above ground. Use those lower temperatures to cool your home. Insulate your home well, so you don't waste the coolness.

If you absolutely must use electric for cooling, remove all heat sources from inside the house, if at all possible. Keep your refrigerator and freezer in the garage or on the porch. (It's not that far to walk.) A refrigerator doesn't magically keep things cold. It removes the heat from the inside of the fridge, and heats up the air outside the fridge. While it keeps food and drinks cold, it is heating up your home. it doesn't make sense to me to use an appliance (refrigerator) to remove heat, and then use a second appliance (air conditioner) to remove that same heat again.

Plant shade trees around your home. They love solar radiation, so let them have it. If you are worried about the trees interfering with a wind turbine, plant shorter varieties. Heck, cover your roof with solar panels and use that solar radiation to generate electricity, instead of all that solar radiation being absorbed by your home as heat.

Make sure the entire surface of your home is light colors. Do NOT have dark colors ANYWHERE on the outside of your home. Light colors reflect heat, while dark colors absorb heat. If your home has black shingles, cover your roof with a white plastic or reflective sheeting.

I've heard that your home will feel 3 degrees F warmer in winter if you increase the humidity. I imagine your home will feel 3 degrees cooler in summer if you run a dehumidifier, but at what price are those 3 degrees? A dehumidifier operates on the same exact principle as an air conditioner, except that a dehumidifier isn't vented outside.

electrondady1 · « **Reply #15 on:** July 30, 2006, 11:10:52 PM »

i want to run 6"-8" intake tube through my cool crawl space and and then up into the living space of my house but i'm not shure what to do with the water that i am shure would condense in the tube .

willib · « **Reply #16 on:** July 30, 2006, 11:11:37 PM »

Was that you that posted about the persians a little while ago, that was an interesting post.

I agree the fridge inside the kitchen is a bad idea , but sometimes there isnt much to do about it.

the dehumidifier is a powerhungy little invention designed to use as much electricity as possible , it seems.

i have two , i found them both , i dont use either for their intended purpose.

one eats 6A the other eats 8A , 960 Watts !! who could afford to run these 24/7 ?

not me..

i'm really looking forward to Fall . lol

on a side note , my attic hit 127 F degrees today , its a shame all that heat cant be used for something

willib · « **Reply #17 on:** July 30, 2006, 11:31:56 PM »

If any water condensed , it would condense on the outside of the tube.

Can you bury the tube deeper than ground level, it would probably work better, then insulate the outside of the tube where it comes into the house , it should be ok.

nanotech · « **Reply #18 on:** July 31, 2006, 04:32:02 AM »

Hrm, I've got two 5,250BTU window units running in my house. They are both on the same circuit as my TV, microwave, 3 lights and computer. All on a 15A breaker.

Either the units aren't 5,250 BTU, they're really efficient (both use the condensate to splash cool the outside coils with evaporation), the breaker is faulty, or something else I'm not looking at.......

whatsnext · « **Reply #19 on:** July 31, 2006, 06:53:05 AM »

That's probably about right. New 5K btu window units draw about 400 watts. I've got a GE 8400 btu 110 unit that only draws 600 watts and does a very good job cooling two rooms. I think it's 10.4 seer. The splash cooling of the condensor must really do something.

John..

SmoggyTurnip · « **Reply #20 on:** July 31, 2006, 07:02:19 AM »

It seems confusing at first but the BTU rating is the amount of heat that is removed from the house. Converting your BTU/hour to watts works out to about 3000 watts. A good air conditioner can move 3000 watt-hours of heat using only 1000 watt-hours of power. It is not making the 3000 watts-hours - just moving it from one place to another. This is why some people use heat pumps to heat their house - use 1000 watts-hours to move 3000 watts-hours of heat from outside to inside.

So your 5000 BTU/hour should use 1000 watts of power or 8.3 amps at 120 volts.

.

SmoggyTurnip · « **Reply #21 on:** July 31, 2006, 07:06:39 AM »

Sorry I meant to say TWO 5000 btu/hour units should use 1000 watts of power.

.

kitno455 · « **Reply #22 on:** July 31, 2006, 08:50:13 AM »

no, if the tube is in the crawl space, the outside of the tube will be cooler than the inside, and the warm, moist indoor air will drop water as it passes thru the tube.

you would need a drainhole in the tube, maybe with a duckbill valve, or you would have to modulate the volume/speed of the air in the tube...

allan

scottsAI · « **Reply #23 on:** July 31, 2006, 01:13:29 PM »

You have that right SmoggyTurnip!

In AC terms:

SEER = BTU cooling / Watt-H

With SEER of 10 and cooling of 10k but, 1kwH power.

As mentioned heat pumps, with geothermal or a nice cool pond or ground water can have a SEER of 30. Same cooling load would then be 10k / 30 = 333 watt-H, not too big for RE. If it's that hot the sun must be shinning.

Even a Super efficient house may need more than 10k Btu cooling, I hope not much more.

My house 1350sqft, has 2 ton or 24k Btu AC. When it's 105 deg outside it runs 23.5hr. I have R38 ceiling and r20 (6" wall) in the walls with thermo windows.

New home could be built with R40 in the walls, R80 ceiling, windows shaded from the sun, may just make it with 10k AC?

What do you think?

Have fun,

Scott.

rpcancun · « **Reply #24 on:** July 31, 2006, 02:58:01 PM »

5 Years thats great, can you share some pics and info on your setup?

what works and what doesn't from experience?

Thx

Rp

altosack · « **Reply #25 on:** July 31, 2006, 07:25:36 PM »

You're on the right track, but it's not quite that simple.

The cooling load is divided into (2), the sensible cooling load (heat) and the latent cooling load (humidity). Doubled insulation will decrease by half the sensible cooling load, but will have little effect on the latent. For that, you need to decrease the ACH (air changes per hour, or air leakage) and not go inside and out so much.

In fairly humid climates (the east, midwest, and south), the latent cooling load can be from 30-65%, so something has to be done about that, too, to decrease the total cooling load by 1/2.

There were some posts on earth tubes above. Care needs to be taken with them to make sure they drain the humidity in a sensible (no pun intended) way.

My ideal system is to have a house bermed on the north side on a south-facing slope (reverse that for south of the equator). Dig a trench 4-6' deep for 3 6-8" pipes (separated in the trench) buried along about 100', slightly (or more than slightly) uphill. 2 of the pipes will have a 180 degree elbow at the upper end, making a loop, the other one will have an inlet for outside air.

The outside air inlet pipe will cool fresh air pushed into the house without a fan, since the cool air will weigh enough to push it down the hill; however, you should restrict the use of this one, since it has to cool down air from outside, which is presumably hotter than the house air, and will eventually warm the trench if you use it all the time. The loop, once it gets primed with a fan should set itself up with a siphon since the air returning to the house is cooler than the air going up the hill, and will run without power (albeit not that fast).

The cool thing about both of these is that the hotter your house is (relative to the earth temperature), the faster the air will flow, and more heat transfer will take place. Also, because of the slope, it's trivial to collect the water and remove it since it will flow towards the house.

Now for the bad news: if you live in the deep South, the earth just isn't cool enough to make this work; also, you do need superinsulation in most parts of the US, otherwise the trench length, depth, and pipe size will be quite large to keep up with the cooling load.

A/C, SchmA/C, we don't need no stinkin' A/C !

Dave

Countryboy · « **Reply #26 on:** July 31, 2006, 07:30:34 PM »

Hi willi,

Yes, I mentioned the Persian air conditioning a while back. They would hand dig 6-10 mile long tunnels called a qanat. This acted like a large, long drainage tile of sorts.

There is somewhere around 50,000 of these tunnels dug, although only about 22,000 still flow water. Those 22,000 tunnels supply the water for 3/4 of the Persian population. Those 22,000 qanats have a combined length of over 170,000 miles.

Digging a tunnel is a lot of hard work. Even if you use power tools, it's a heck of a daunting task. However, it isn't that difficult to lay several lines of drainage tile in your yard. It may be easier to plug in an air conditioner to cool your home, but in the long run that drainage tile underground air passage will be tons cheaper, plus it is RE.

wooferhound · « **Reply #27 on:** July 31, 2006, 10:58:44 PM »

Solar Powered Air Conditioning

http://216.239.51.104/search?q=cache:2CRopvJgzfUJ:techref.massmind.org/techref/other/spac.htm+%22air
+conditioning%22+solar&hl=en&ie=UTF-8

dinges · « **Reply #28 on:** August 01, 2006, 08:11:09 AM »

Excellent site by Gary, one that I visit daily:

http://www.builditsolar.com/Projects/Cooling/passive_cooling.htm

thefinis · « **Reply #29 on:** August 01, 2006, 02:45:09 PM »

"i didnt know there was a monsoon season in Arizona .

i would like to hear more about your evap cooler ?

how large is it?

how good does it work?"

Willbur I'll try and answer your questions.

The subtropical jet off the pacific feeds moisture to the desert southwest and into the Rockies during the summer months. The thunderstorms it feeds are most of the rainfall for the year for many areas.

In west Texas I used an evaporative cooler for years. I don't think it saved much energy as it ran most of the time. Seems like they had a 1/3 to 1/2 hp fan motor don't know what draw the water pump had. The bigger the unit with slower air flow per sqft of pad means the cooler the air is ie don't get the little one and run it on high get the big one and run it on low. They work great with low humidity(-25%) and drop temps by 15-20 or more if sized right plus they exchange the air. This is great if you are cooking or creating heat or have an area to cool that is poorly insulated or drafty. We ran it all night and slept under covers and would turn it off in the morning until the house started to heat up about lunch.

With 25-50% humidity you should get a 10-15 degree drop if sized right but house humidity is pretty high. Above 50% you still get some cooling and air flow but the high humidity makes it feel like all you are doing is running a fan. We would get condensation on items in direct air flow at times during the night if humidity was high. These are just close figures as how you size and run the unit will effect how well it works.

These might be well worth the effort for off griders in low humidity areas as it shouldn't have near the surge current draw that ref units have. It could be run with dc motors but remember that the air flow is part of the cooling effect so try and find a good balance between sqft of pads, air flow, and humidity level. You could use one without the fan on if you have good breezes from the right direction and have a house with windows on the downwind side. If the unit is on the upwind side open the downwind side windows creating a draft that flows through the unit with the water pump running. I used to do this when we had good southwest breezes not as good as the fan running but a lot cheaper.

Finis

Norm · « **Reply #30 on:** August 01, 2006, 06:18:11 PM »

Well you could suck the heat out of the attic

and thru your clothes dryer....??

Not a new idea...its been posted before...

Probably disadvantages to that too....??

( :>) Norm

Titantornado · « **Reply #31 on:** August 01, 2006, 07:05:07 PM »

Well, while were at it, more on earth tube cooling:

http://mb-soft.com/solar/intake.html

jimjjnn · « **Reply #32 on:** August 01, 2006, 07:19:34 PM »

Norm , It really worked for us even in the sunny winter days. Course, our laundry room was on the second floor and vented out through the wall. The dryer had a cabinet around it with a door and so it was easy to vent from attic to cabinet. Dau loved it as the elec bill took a big drop. I was worried that the motor would get too hot but never gave any problems. The electric heater coils had thermostats so they actually cut off most of the time. Had to disconnect only one time in winter when we had snow on the roof for 6 days.

News:

Author Topic: How to cool the home. (Read 6199 times)