Cool tubes

Started by jonsey/downunder, May 01, 2005, 05:29:00 AM

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jonsey/downunder

Thanks for the link to the pdf of the book Amanda; it's one I missed. I wouldn't mind the link to the discussion group you mentioned if that's possible.

Glenn, I have started this as a new topic in the general discussion in case there are a few more ideas floating around.

My plan for the cooling tubes is pretty much along the lines you suggest. The system will be an open loop, with the open end under the house. If needed, I will install a blower on that end. The tubes will vent into both bedrooms and will mainly cool that area. Through the summer, the temps in this area are mostly in 40's, the night temps are only a few degrees lower. We use what you guys refer to as a swamp cooler now, works great but is noisy, uses a heap of water and power. There is no provision for such a beast in the new house so even if we can get a bit of free cooling it's a bonus.

The tubes are 150mm-storm water pipe and will slope away from the house. There will be a drain at the lower end with a sand bed under that. I will install a pull through system in the tubes as I go. There will also be provision for flushing. The humidity in this area is between 30% and 50% through the summer so I'm hoping moisture will not be too much of a problem. There will be two 40-meter loops buried about 1.5 meters, I would like more but room on the block is a problem. One bonus we have, the ground stays moist at a meter down, this will help with the cooling.
The tubes will just be a part of the passive cooling setup and will complement the shading, ventilation and landscaping design of the house.
The vents in the cathedral ceiling work quite well for now. I will, be looking at some kind of solar chimney later on, maybe incorporating a heating system there as well.
jonesy.
I've got nothing on today. This is not to say I'm naked. I'm just sans........ Plans.

JRR

I intend to try something similar (in southeast USA), but I have been thinking of a once-thru uphill system.   Electrics will be buried with pipe for a pusher fan if necessary.


jonsey/downunder

Look here it may be near enough for you to check out in person.
http://www.solar.org/
I've got nothing on today. This is not to say I'm naked. I'm just sans........ Plans.

JRR

Thanks.  Fairly close by.  I'll try to give a visit this summer.

Amanda_931

Hmm.  Never heard of those guys.  Somehow I thought it was going to be Sequatchie Valley.  So now I'm reading about cool tubes in the South-east.  Something I'm really interested in.

Cob list

ESSA

ESSA2.

The first two do have archives, not sure if they are up yet for the third--lost the lovely University server.  I never use the archives, just search for the topic, generally find myself going on and on.

Has everyone seen this link?

www.greenershelter.com

This is Don Stephens' web site.  He calls his system AGS--annualized geo-solar.  Get your tubes down far enough (and don't run into ground water!) and you end up doing your exchange about six months later--so, cool inside in the summer, warm in the winter.

He does say, on the web site, that the slower the better on moving the air through the tubes because you want the air to have given up all its temperature differential before (as would be the ideal) it reaches the other end.

(The other year-round version is PAHS--John Hait--the .pdf link posted earlier.  He claims to have a new version of his twenty-year-old book out, but I'm not the only one who wonders if color pictures is the main difference.  Right now you can get the new one as a .pdf file for $50.00, and the old one in print for $49.95--probably plus shipping.  The ESSA  (2) list is whining about that right now.)

Mike Reynolds wrote something about just cool tubes in an early book that I no longer own.


JRR

I wonder if any of the "cool tube" (aka "earth tube") experimentors plan to insulate the pipe as it passes up through the near-surface earth?  It seems to me if they fail to do this they will have lost some of what they went so deep for.  ???

Amanda_931

Yep.

Hait especially, put  insulation all around his mostly underground houses, and out for many feet around the house.  Stephens not quite so far out, only about six feet or something.

I think Reynolds had his tubes going mostly down, so it didn't apply so much.  (It would to those of us in the east)

Shelley

Read this link and the earlier ones.  Got interested.
Followed all the links and found some other ones.  Wound up on some DOE sites.

Conclusion that I drew.  Need a chimney.   Chimneys are expensive, inefficient, and design unknown.

Earth tubes are a great idea.  Design unknown.
Too many variables.   Earth temps vary too much...even at the same site...to engineer a standard.

And, remember, we're in an area where the night/day temps vary 40-50 degrees.

Have I missed something? :-/

Let me know, cause we'll pour the slab in < 30 days.

What I'm thinking now is that we'll just plod along, building for solar gain in winter....doing the the things that are recommended for summer...plugging all the air leaks like we always do.

We are thinking about a plumbing system that will allow us to circulate the RIH water to the cold night air and cool it the slab that way.  That seems to make sense to us.
It's a dry heat.  Right.

glenn kangiser

#8
There is a house near here with radiant floor heat with a big storage tank - I would guess 2000-3000 gallons.  Are you using a storage tank, Shelley?  Just wondering about how your system will be set up.  Seems to use it for cooling you would need storage to hold the cold.  Would you use radiators of some sort to exchange slab heat for air cooling ???

It won't work for me here as nights are about 80 degrees f. for several weeks on end.

Are you putting pex in the floor no matter what?  I put it in 3 sections to play with-
"Always work from the general to the specific." J. Raabe

Glenn's Underground Cabin  http://countryplans.com/smf/index.php?topic=151.0

Please put your area in your sig line so we can assist with location specific answers.


jonsey/downunder

#9
Hi Shelley,
That's pretty much the research that I ran into on the web. There is screeds of stuff along the lines of "the therory is great but there are all these problems blah, blah blah."
I am working on the principle of "suck it and see" and have gone ahead and put tubes in the ground. I figure what the hell, if it doesn't work, I'm out a days labor and a couple of hundred bucks.

I took some ground temps at the bottom of the trench and found them to be around 21dgr's. That is about what I would have expected based on my research of the mean average temps in this area. We are just coming out of our summer with temperatures of around 40dgr's plus. The last month has seen temps around 35dgr's. The climate in this area is very dry with an average humidity of between 30% and 50% through the summer. It would seem that around 80% is where you would expect to have problems with the system.

When I installed the tubes, I put a slope in the pipes with a drain hole at the lowest point. I have a soaker line running on top of the tubes to keep the ground moist and the pipes are run under garden beds. If you can keep the system in a shaded area and the earth moist you would expect better cooling.
I think most folk expect the earthtubes to work as a full on air conditioning system, and when it doesn't, see it as a failure. It should be looked at as part of a whole passive system, along with shading, insulation and all the other things needed to keep the house comfortable.
At this stage, I will not bother with the chimney and will simply install a couple of small fans to push the air through the tubes. These fans don't need to be that big, as it's only a small amount of air going through the system. The slower the better.

With our tubes I am expecting to use them solely as a cooling aid, the heating is not a problem around here. I can't say at this time if it is all working as planned but will certainly keep you all informed as we progress.
jonesy
I've got nothing on today. This is not to say I'm naked. I'm just sans........ Plans.

jonsey/downunder

#10
Shelley,
Just thinking about your idea for night cooling. I remember reading about a guy over here that lived up in the Simpson Desert he used something similar to keep his beer cool. It was an old fridge turned on its side and opened to the night air (I think he had some sort of reflector on it). The door was closed in the morning before the sun started heating everything up. The night temps in the desert drop almost to freezing, through the day they can be up to 50dgrs. I see no reason why you couldn't build something similar, maybe with some tubing coils inside. I think the article was on a solar box-cooking site.
Our head researcher may be able to dig it out for you. ;D
jonesy.
I've got nothing on today. This is not to say I'm naked. I'm just sans........ Plans.

Shelley

Going to put the PEX in regardless.  But remember this is metal building/shop/guest quarters.

We've had RIH for years in several houses.  Weren't going to bother until we built the house, then thought what-the-hey....why not?

Idea for cooling not fully formed.  But since the mechanicals will be in the shop we can figure that out later....as long as the rough-in is there.

There's a company back East that's selling a package for doing it.  Way overpriced.  Combo of pex running underneath metal roofing.  Can't tell from the pics how they're protecting the pex from the screws.   Don't know how we'll do it yet.  Just need some way to exchange the warmer water in the slab with cooler water from outside.  Stop the process at daylight.

One of the solar guys here who's building a house is doing a simpler system.  He has several columns designed in his house.  Just DW rectangles  holding water tanks.  Will circulate that water to the roof at night to a panel.  KISS.

I'm sure that whatever we come up with will have to be suplemented by evaporative cooling in the afternoon.  We don't have enough mass in the metal building.  But if it works somewhat, we can transfer the idea to the adobe house.  With our temp drop at night, seems like a reasonable idea.

Jonsey,
No shade here and no damp earth either.  But don't I remember an old MEN article maybe in the 70s?  Home built house in the CA desert.  He did something like the cooling tubes.  Think he had some kind of chimney too...tho at the time I didn't realize what it actually was.
It's a dry heat.  Right.

glenn kangiser

#12
I just typed the worlds longest reply- hit the wrong button and it's gone.

Are you insulating the roof, Shelley?  If not, you can fasten to the purlins with single SD screw clamps -   If insulating you could put pex  above the insulation.  We used 2" UL Vinyl covered insulation years ago sandwiched between insulation and purlins.

Switching could be done with a solenoid on one side and a reverse flow check valve on the other side to prevent back flow to heater - both sides of cool line tee'd into the heat line.  If done right you could use the same pump for heat and cool.  A cheap timer could control the cooling system.
"Always work from the general to the specific." J. Raabe

Glenn's Underground Cabin  http://countryplans.com/smf/index.php?topic=151.0

Please put your area in your sig line so we can assist with location specific answers.

jonsey/downunder

#13
Sounds like you are pretty much on to it Shelley. A solar water heater will work in reverse. All you need to do is divert the hot water during the day or cover the panels to stop the daytime heating. There is a forum on alternative air-conditioning that discusses these systems; you may pick up some useful tips there. Amanda will probably be able to provide a link for you.

The shade I am talking about is more insulation than shade. This is simply provided by running the pipes under lawn or garden beds. Normal watering of same provides the moisture. I have the added insurance of a soaker line buried with the tubes. I think the odd short burst of water down the line through the summer will assist in keeping the ground from drying out.

Just diverting a bit here. NSW has recently introduced new building codes that come into force on the 1st of July. All new homes will need to comply with water and energy saving guidelines. There is a list of measures suggested to assist in complying. This has caused quite a stir with the local builders. I am hearing stuff like "woe is me, this will put us all out of business, the cost of building a house will go through the roof". It seems that most don't understand that these measurers are simply a matter of good planing. There is no reason that good passive design should cost any more than the normal building costs. Things like, proper orientation, eaves that are designed for local sun angles and insulation will take care of most of this. A few others are, good landscape design, thermal drapes and light colored or reflective roofing. Mostly you need to have a reasonable understanding of the local climate.

A good example of poor planing, is a home not to far from me. The climate in this area is arid and hot. The summertime temps are constantly in 40s, at night the difference is only a few degrees. There is little rain, about 400mm per year. The winters are mostly mild although we can get some cold southerly winds. The area is mostly flat treeless plain.
This house is your typical Mac mansion. Two story brick veneer, no eaves and a black tile roof. All the large windows face the south, because that is where the view is (sun is in the north down here). The house is built in the middle of a large open paddock (no shelter from the southerly winds) The landscaping is typical English garden, all lawn and roses (needs a heap of water). I would bet that the only insulation is the foil building paper. Basically, what you have is a large brick sitting in the middle of the dessert. You can imagine the cost of running that outfit.  ???

OK now that I have had my daily grump, I'm off to fix mothers' bike.
There you go Glenn, bet you don't know what I will be up to on Sunday.  ;D
jonesy.

BTW, since I am too lazy to convert the metrics for you, here is a conversion table to translate into American. A bit agricultural, but near enough to get an idea of what I'm on about. You can save it to your desktop (feel free to improve it if you like).

http://users.tpg.com.au/jonsey/Conversion%20Table.xls
I've got nothing on today. This is not to say I'm naked. I'm just sans........ Plans.


glenn kangiser

How did you know I was going to give you a bad time about the metrics, Jonesy ???  Can you foresee the past ???

Okay - thanks for the conversion table - they were trying to teach me metrics in school and telling me how much better they were than our system, but I just chased girls all night and slept through the classes :-/

I guess that's what I get-- have to convert with a chart. :o
"Always work from the general to the specific." J. Raabe

Glenn's Underground Cabin  http://countryplans.com/smf/index.php?topic=151.0

Please put your area in your sig line so we can assist with location specific answers.

glenn kangiser

Crikey, Jonesy.  That conversion chart's a beauty.  You must be way ahead of me in Excel.  I can usually get it to do what I want but never did find all those pretty colors.  I use it mostly for estimating. ::)
"Always work from the general to the specific." J. Raabe

Glenn's Underground Cabin  http://countryplans.com/smf/index.php?topic=151.0

Please put your area in your sig line so we can assist with location specific answers.

jonsey/downunder

I dunno mate? Not only are we pretty, but geniuses as well. Now that could spell trouble. ;D
jonesy.
I've got nothing on today. This is not to say I'm naked. I'm just sans........ Plans.

Amanda_931

Hmmm.  I don't know anything about an alternative air conditioning forum.

But it sounds like it might be wonderful--or full of people with bees in their bonnets whose ideas range from the "won't work in the humid south-east" to "pretty goofy."

No-electricity ways to make your house friendly to people allergic to lots of things is on my mind right now.

But I think I'll keep the cats and dogs.

jonsey/downunder

I found the air-conditioning forum while looking for stuff on the cool tubes. I didn't keep the link to the site though and a quick search since hasn't turned it up. There seemed to be a lot of knowledgeable folk from all over on there with a heap of ideas. I think it may be well worth looking for. There was a lot of information on making standard systems work well and quite a few home built systems as too. If I get time in the next day or two I will try to find it again.
jonesy
I've got nothing on today. This is not to say I'm naked. I'm just sans........ Plans.

Amanda_931

I'm a couple of pages into a search (the greenbuilding forum isn't turning up for some reason) but I did find this--huge, deep, long tubes with drains, powered by convection (solar) chimney.   A pretty far cry from what those guys in Georgia are doing, but you are SOL if you're building on a lot, or in the woods, etc.:

http://www.i4at.org/surv/aircond.htm



Amanda_931

Could you just not drain your cool tubes and run a circle with your pipe through an air-to-air heat exchanger, cooling your room air without exhausting it, sending the cool tube air back underground?

Couldn't use solar chimneys (or wind scoops or whatever we're going to agree to call them) if you wanted to keep the mildewy air away from the building, I guess, but....

Underground air needs to go as slowly as possible.  Would that be a problem?

glenn kangiser

#21
I don't see any reason that you couldn't hook the far end of two tubes together and make a closed loop, Amanda, with a fan on one side to keep flow in one direction.  Then you are not fighting cooling massive quantities of outside moist air, so no great amounts of moisture to deal with - may work as a dehumidifier if you have a small drain to get the water out of the tubes..  Sounds like it's worth a try.  You probably wouldn't even need the heat exchanger if you kept the intake and outlet in separate areas of the house to move cool air throughout and prevent short circuiting the air from outlet to intake.
"Always work from the general to the specific." J. Raabe

Glenn's Underground Cabin  http://countryplans.com/smf/index.php?topic=151.0

Please put your area in your sig line so we can assist with location specific answers.

jonsey/downunder

#22
Amanda, I found that link.
http://groups.yahoo.com/group/solar-ac/messages/421

There are a couple of methods that you could use. One is the open loop like I am using. Another is a closed loop. This is where the air is drawn from inside the house and pumped through the tubes back to the inside. There is also a heat exchange system. With this type, the tubes are filled with water, which is continually circulated through the pipes. A heat exchanger is placed in the system and can be incorporated into your standard ducted heating or cooling system.
This site is worth looking at, this guy has quite a few pages on cooling and heating ideas.
http://mb-soft.com/solar/index.html
I've got nothing on today. This is not to say I'm naked. I'm just sans........ Plans.

Amanda_931

Thanks for the links, Jonesey.

The idea of the heat exchanger would be so you wouldn't have to have spore-laden underground air in your house.  Just the house air recirculating.  You'd have to deal with ventilation separately.

That one link was suggesting that huge corrugated pipe that we use for culverts.  Almost impossible to drain completely.

JRR

#24
I have a variation of the "earth tube" idea I've been playing with.   I have a country property, now within city limits, that has an old house and an old dug well on it.  The house needs much work and maybe it'll get some this year.

The dug well needs cleaning and I will probably pay someone in the business to do this for me.  Where allowed, new wells installed in this general area today are often bored by machine ...  to a diameter of 24" (I believe).  My local municipal restrictions no longer allow well-water use except for outside use and heat exchange.  Water can be expected at 50', or less, depth.

Therefore, if the well is reconditioned, it could be a source for gardening water.  And ...

If a capped-off (say, 12" dia) pipe were installed to several feet vertically below water surface .... with a small furnace-type condensate pump inside at the lowest point .... and a smaller pipe (say, 8" dia) were run down inside to within a foot or so of the bottom of the larger pipe ... would this all make for a "conditioned" air source?  Down the larger pipe, return up the smaller pipe?

Advice?