tower and coil space cooling

[d34]

good info guys... keep it coming! 

[Ronmar]

Yep, all excellent points Frank.  Definitely some calculations involved to determine feasibility and design parameters.

[Crofter]

I am fortunate to live where very little air conditioning is necessary, but I have traveled and worked in locations where life is really miserable with the heat so I can sympathize with the desire for air conditioning and the thought of finding it virtually for free is enticing. Certainly there are moves you can make to your advantage if you are designing from a blank sheet. Reading the links on some of the passive cooling schemes shown makes me think from the cost that it was done by the very wealthy and many of them are for quite exclusive climate conditions.

If you would be controlled at all by building code, insurance, mortgage etc., unconventional designs are expensive to actually put into being. Some of the ideas shown like running water in earth tubes openly connected with living spaces is only a step above open street sewers as a potential health hazard. That there are suggestions about sources for demineralized water to continuously bathe the evaporative cooling devices is a bit telling. Are these schemes that work only where total costs are of no consideration? I am skeptical that some of these are bragging about their countries venerable technology. I think Wiki mentions something about being unsubstantiated. A bit like the saying that the good old days are remembered most fondly by those with questionable memorys.

Anyways I would be very interested in seeing designs that really will function and give good bang for the buck in the face of todays conditions.

[sailawayrb]

Definitely pros and cons associated with this.  I think this has good merit if you live in a climate that is hot and dry, both day and night.  If you live in a climate that is humid or is only hot during the day (i.e., gets cool at night), a better alternative might be a well insulated house with either active or passive whole house ventilation.

At my future location in southern OR, it can often be 100+ deg F during mid-day during the summer, but the temp will always drop to 50 deg F at night.  So I am thinking whole house ventilation chimney (with roof egress zone shared with the masonry heater chimney) likely wins out.  A well designed passive solar house tends to stay pretty cool anyhow because of all the thermal mass in the house, because it is super insulated, and because little sunlight/heat enters thru the windows during the summer months.

I have never been a big fan of earth tubes for some of the reasons mentioned.  Plus, with my luck, one of my wife's cats would crawl in and get stuck.  Then my life as I know it would be over  

Bob B.

[mobile_bob]

Bob:

i have kind of come to the same conclusions, in  east central kansas, it gets hot as hell in the summer months
not unusual to go well over 100 degree's for weeks on end, however it generally cools to the mid 60's at night.

the problem is the humidity is also higher at night, so this is my thinking

insulate the living crap out of the house, (existing structure), there are already no windows on the west side, which is a plus
but also need to make sure the other windows are efficient units, then

i will probably have someone come in and take out the concrete floor in the lower level (which is now a garage) insulate
and pour a replacement slab with pex  so that it can become a large thermal mass, (hot and cold depending on season)
and i am also thinking of large centrally located stone fireplace with additional thermal mass and pex running through it as well.

then in the summer months close up the house during the day, to limit heat gain, and at night use the cooling tower
to remove the heat from the thermal mass of the floor and fireplace mass,

even though the humidity is higher at night and that will limit the wet bulb depression sustantially,  i think it is possible
to cool the thermal mass down to perhaps 5 degree's under the outdoor ambient dry bulb temperature, or about 60degrees F

so by morning the slab and fireplace mass should be cooled to somewhere close to 60degree F,  or at least 65 degreeF
which if the house is closed up tight and the heat gain is limited, i believe i can maintain the inside temps to something
under 80 degree's by late afternoon,  at which time if it is necessary i can engage the forced air system to moderate the temps
for any shortfall in the more or less passive system.

so in the end i should be able to cut the A/C run time by at least 50% if not closer to 75% or more on some days.

on cooler drier nights it is possible to get temps below 60 degree's off the cooling tower.

then there is also the possibility to use a water to freon condenser that uses the now existing cooling tower so that
the forced air A/C system would run with less power or more efficiently.

i am thinking why not?  the place is relatively small, the climate has a broad temp swing from day to night, and i have a real interest
in design and build of such systems anyway. 

besides i have an aversion to hot summer heat!

bob g

[sailawayrb]

Bob G.,

Sounds like a great plan to me.  Just getting mass IN the house and being WELL insulated does a tremendous amount of good in stabilizing the inside temp and minimizing heating/cooling requirements.  Might want to install a couple ceiling fans too.

Speaking of hydronic heating/cooling, I just learned that Amazon is finally shipping me the latest revision of Sigenthaler's "Modern Hydronic Heating".  I have been patiently waiting for it to be released for over 6 months now.

Taco has some nice, free hydronic design software too:

http://www.taco-hvac.com/en/products/Design%20Tools/products.html?current_category=27

Bob B.

[Tom Reed]

One simple cooling tower I've used was just a shower pan that was surrounded with 6' walls with 2" redwood slats tilted to drain into the pan. A sprinkler head centered at the top introduced the warm water. It worked very well.

But to do what you want Bob, you might want to take a look into some hot water solar panels. They can be used for heat during the winter and cooling during the summer by radiating the heat out into the sky at night. If you run the numbers you might be pretty surprised. I've heard of systems freezing at 44f. Our home has pex tube in the basement and main floor slabs and I've thought of cooling with the hydronic loop, BUT have decided not to try it due concerns about condensation. In an appt I lived in in D.C. there was a coil, probably from a freezer case going across one side of the living room above the sliding glass door. Cold water was circulated through this coil and water dripped into a "gutter" that surrounded the bottom and front of the coil. The same coil received hot water in winter. It worked very well.

In the design of our home we included a lot of interior concrete floors as thermal mass. The most we've seen for day time temps here is 113f, the house got up to about 75. It is also difficult to over heat the house with the wood stove and temps only drop about 3f with over night temps in the low 30's.

[Crofter]

Sailawayrb, I like that idea of the ventilation chimney sharing the space of the masonry heater stack; Gosh, I am visualizing a spiral staircase around it! I like passive but it is not because I am a stranger to mechanical complexity; I made my living for the most part as a steamfitter, but I am well aware of the warts that show up with age on a system. I dont like being a slave to maintenance after the creative glow has faded.  The slab heat hydronic is ultra nice heat, though I have reservations about it for cooling the living space directly but if not it is still a plus as you could use its cool liquid to enhance refrigerant air conditioning. Whatever a person could do to make as much of the system as possible work for both winter and summer would be a plus. The wet tower idea I would need some more convincing on!

An older gentleman who is dead now built a lot of active solar and heat storage ideas into his home 40 years ago when that technology was still quite new. His system was pretty complicated and personalized and only one of his techie friends could look after it when he was away. When it came time to sell they could not get a decent offer on it. Since it was on 11 acreas it eventually sold but for half the price a conventional system house would have fetched. The new owner demolished it as he only bought the lot. Fortunately it was after the old fellow died.

[Crofter]

<SNIP> take a look into some hot water solar panels. They can be used for heat during the winter and cooling during the summer by radiating the heat out into the sky at night. If you run the numbers you might be pretty surprised. <SNIP>

Tom are these evacuated tube units? I like the double duty winter/summer idea.

[sailawayrb]

Great perspective as always Crofter.  As much as we love our creative, innovative systems, they are not always well received by others and they can adversely affect future value and sale.  I also like to avoid unnecessary complexity/technology whenever possible too. Complexity/technology should always have to earn it's place into a design.

Tom, while I also share you concern with hydronic cooling causing condensation, I am completely ignorant of this subject and will need to study up on it before I could provide anything worthwhile.  I am hoping to use stamped/dyed concrete for the slab surface inside house (or perhaps natural rock looking tile).  I am also thinking of modifying the house design so the main interior wall between bedroom and great room is a real brick wall.  I put some preliminary house design renderings on Marcus's project thread:
 
http://www.microcogen.info/index.php?topic=1412.15

Besides adding contrast and looking nicer than all sheetrock, this brick wall will provide even more thermal mass.  Given that the ceiling height is 10 feet, I will likely need to have another footing just to handle the load from this wall.  Will likely need to consider seismic as well.  Any thoughts would be most appreciated...as I am not currently a master brick layer either...but I will be...

Bob B.

[Tom Reed]

I was talking flat plate collectors, seems that they radiate as well as adsorb heat.

We have a acid dyed light weight concrete slab on the main floor of our house. My concern is that the subfloor would rot if moisture condensed on a cool slab. As long as you're above the dew point you're ok, but that will change over the course of the night.

[Crofter]

I think condensation could be a concern for mold on anything like bedclothes or curtains that touch the floor as well as slippery if the humidity reaches the dew point. Also I see possible stratification of a cold layer at the floor that is not easy to stir up. Ok if it is sweaty feet and not sweat on your brow that troubles you. easier to cool you if the cold air enters high and sweeps down and across.

Just wondering what depth drilled wells come in at and cost per ft in Bobs locale. Would not even have to be potable or have a high flow rate if it were used as a very long underground  heat sink and heat source.

[Crofter]

Tom, thanks on verifying plate collectors. Solar hot water may be next summer project. DHW presently by wood heat and that sure is worthwhile. Dont want to burn wood though in the summer. Trying to see what I can reduce useage to with some solar electric in the future. Dang we sure get used to using a whack of elctricity; at least a lot when you consider the cost of replacing it by solar.


RB, on the brick work; do it yourself if you need some creative outlet and dont have other things you would be better paid doing, Lol!  I have laid 5 or 6 hundred blocks and built a chimney and a brick half wall behind the cookstove. I find it disgustingly slow compared to what we see for results from a real mason; probable less than 20%. With the construction industry what it is you could probably get one at the Salvation Army soup kitchen and you just mix the mud for him and look at the prints!

[Mack_59]

I recall reading somewhere on one persons house that they had radiant heat for the floor slab and then for cooling they had installed some kind of flat absorbtion plate chillers up near the ceilings with fancy controls to monitor humidty in the house so condensation would be eliminated. With a well insulated tight house there is also the need for air exchange to keep indoor polutants down. I think this house was located near Pueblo Co so there was not much outdoor humidity to begin with.

[sailawayrb]

RB, on the brick work; do it yourself if you need some creative outlet and dont have other things you would be better paid doing, Lol!  I have laid 5 or 6 hundred blocks and built a chimney and a brick half wall behind the cookstove. I find it disgustingly slow compared to what we see for results from a real mason; probable less than 20%. With the construction industry what it is you could probably get one at the Salvation Army soup kitchen and you just mix the mud for him and look at the prints!

Yeah, I have always been happiest doing things myself and the results have always better than the best professional would ever achieve. Slow going is OK as it is more the journey than the destination for me, and the satisfaction of doing something right yourself lasts forever. Of course, what else would you expect to hear from an engineer, glass blower, and sailor...

Bob B.