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Lakegeezer
07-18-2006, 07:31 AM
The high temperatures and high energy costs has me thinking about cheaper ways to stay comfortable. Fifty feet from the house, and 30 feet down, the lake could provide an unlimited supply of cool water in the summer and 39 degree water in the winter. Would a heat pump work for both cooling and heating? What would the design look like?

ApS
07-18-2006, 08:47 AM
You could probably "mine" Winnipesaukee's temperature differences, but should have to pay for deep-well injection of the exchanged water—a very costly remedy to recoup any savings.

In certain Florida counties, deep-well injection of "Energy-used" water is prohibited: Those counties require that well water drawn for air conditioning be discharged directly onto the ground: Not such a good option among NH's lakefront slopes and new ridge-developments.

Though I located a large aluminum radiator, fan, hose, and small pump for some low-tech lakewater A/C here, I was pleasantly surprised at how efficient a single $85 "window-shaker" A/C was at cooling my uninsulated camp. My acre of pine-forest shade undoubtedly helps.

Yesterday, though, I threw a chair into the lake to cool off for an hour—after dragging my feet behind my Sunfish sailboat for an hour! :coolsm:
While I applaud new energy initiatives, Lake Winnipesaukee—large as it is—isn't inexhaustable if "everybody" exploits it.

Anybody need a large aluminum radiator, fan, hose, and small water pump? :emb:

jimbob1603
07-18-2006, 09:58 AM
My brother in PA uses groundwater from two drilled wells to help reduce energy costs at his house ..... works well and has paid for itself.

Exploiting the thermal mass of the lake is a fantastic savings opportunity; but if every waterfront home did this, the lake would become a swamp in twenty years. It is an intriguing concept; but surely has its long term problems.

Now, if someone could could find a way to exploit milfoil weed to pay property taxes; we'd really have something!

Bear Islander
07-18-2006, 11:20 AM
I have my water intake quite far out in the lake in about 20' of water. That way I get cool water in the house at the hight of the summer.

I have imagined going deeper to get some really cool water for air conditioning. As you mention, it gets real cold below 30'.

SIKSUKR
07-18-2006, 02:43 PM
I believe the practice of removing water and returning it at a different temperature is not allowed in this state.(Except if you are nuke plant or power plant apparently).I have the Merrimack River right next to my mill building in Manchester and we have discussed this many times.As a matter of fact,with this heat we were talking about it yesterday.As far as I know,you are allowed to drill wells to use the btu's for heating/cooling.I think the payback is pretty cost prohibitive though.

jrc
07-18-2006, 07:45 PM
I think most residential heat pumps use a closed system. A fluid (maybe water or anti-freeze) is circulated through loops of pipe in a well or a lake. The lake/well water never leaves, it just cools/warms the fluid in the loops. The heat pump uses that fluid to operate.

If it's against the law to use the lake for cooling/heating, many of the big cruisers on the lake are breaking the law. Many marine air conditioners pump lake water for cooling.

As to long term warming effects:

According to one website, the lake holds 625 billion gallons or about 5 trillion pounds. One BTU is required to raise a pound of water one degree. So 5 trillion BTU's would raise 5 trillion pounds one degree. An average home air conditioner is 10,000 BTU per hour. So it would take a million home air conditioners running for a 500 hours to heat the lake by one degree.

Orion
07-18-2006, 10:53 PM
If it's against the law to use the lake for cooling/heating, many of the big cruisers on the lake are breaking the law. Many marine air conditioners pump lake water for cooling.

Actually, every single powered boat on the lake is exchanging hot water for cool lake water.;)

Mee-n-Mac
07-18-2006, 11:47 PM
Going back to your original question of efficiency and lower cost ... I'm guessing that because Canada was pushing (http://oee.nrcan.gc.ca/publications/infosource/pub/home/heating-heat-pump/booklet.pdf) for such things they must be more efficient and cheaper to run. APS does a good job explaining what a simple home built system could be, whether such a thing would be cheaper to run (all legalities aside) vs a commercial heat pump or normal AC is another question. Some light reading FYI ...

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

http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatpump.html

Maybe the thing to do is to move the habitat to the water (http://www.izaak.unh.edu/museum/Marine/edal.htm) and not the water to the habitat. It's been done on the Lake before ... ;)

ApS
07-19-2006, 05:41 AM
"...So it would take a million home air conditioners running for a 500 hours to heat the lake by one degree..."
Whilst some necessary shortcuts were used to arrive at your figure, the water heated by far fewer air conditioners would eventually arrive at the surface thermocline. [And not be a 1° increase equally-distributed amongst the lake's 625 billion gallons]. Just 1° increase at the surface would promote Winnipesaukee's present algae and milfoil woes earlier.

Why not use the mass of the Earth as a possible workaround?

Use well water instead of lake water, and call it "geothermal energy"—which I think jimbob1603 may have previously referenced. The exchanged water could then be injected at a much greater depth than the supply well (Or below a suitably-deep "impermeable clay" layer).

"...Now, if someone could could find a way to exploit milfoil weed to pay property taxes; we'd really have something!
That's a good one: New Hampshire pays you to take their air-dried and compressed "milfoil logs" for the woodstove? :laugh:

jimbob1603
07-19-2006, 09:57 AM
Using drilled 6" wells is a necessary evil for those without waterfront property ..... wells are the only way .... at about $6K each. Dropping a couple 1" polyethelyne lines into the lake would be infinitely more cost effective.

I remember way back in the college days, another tenant (an engineering student, naturally) in our building set up a radiator & fan in his bathtub; and exploited the "free" domestic hot water (included in the rent) to help defray his heating expenses. Despite our admiration for his ingenuity, it ticked the rest of us off because there was little hot water for the rest of us to use for showers, etc.

Hermit Cover
07-19-2006, 09:15 PM
Jimbob....try this website as a possible resource.. www.radiantmax.com ..I have found them to be quite expert in the geothermal heat / cool energy field.