We are building a new house in a rural area. Rather than drill a well for water of dubious quality we are having city water trucked in.
So my question is: Seeing as we have 3600 gallons of water sitting in 3 cisterns in the basement would it not be possible to run pex through the tanks and to a heat pump (and then on to the radiant floor heating) just as you would run tubing through a lake or underground to form our own mini geothermal environment?
Does this make sense?
Thanks for any insight.
Puzzle
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3600 gallons is not a lot of water, and probably not enough to act as the heat sink on a geoexchange system. That amount of water is about one million BTUs (for an 18F temperature swing in the cistern) -- the heating equivalent of a gas-fired furnace running for eight hours.
Edited 7/6/2006 1:01 pm ET by TJK
Thanks. I'm not sure I understand the science there but I sure appreciate the advice! I guess I won't run out and buy a heat pump today!
No way would it work.
A heat pump basically only MOVES heat from one place to another. So when you're trying to heat your house, you'd have a hugh mass of very cold water and/or ice in your basement absorbing heat.
When you were running the AC, you'd have a huge mass of steaming hot water in your basement that would be radiating heat.
You need to transfer the heat to/from somewhere OUTSIDE the house.
Ohhh! Yikes! OK .
Thanks.
Hi,
You mentioned you are going to truck in water. Have you thought about a roof water catchment system instead?
We stayed in a house in Taos (8 inches of rain per year) that (with some water use management) was able to meet all of its water needs from what was captured on the roof.
If you want to go this way, you need to design the roof for that purpose, so it needs to get into the plans early.
http://www.twdb.state.tx.us/publications/reports/RainwaterHarvestingManual_3rdedition.pdf
Gary
http://www.BuildItSolar.com
Hi Gary,
Yes, we will have that as well. We do have a great deal of roof area. I doubt that we could supply all of our water needs though especially in winter- we live in Northern Canada. And we probably need a first and second flush diverter (!) the house is pretty much in the middle of a forest.
By having 3 cisterns we can choose to designate say, one of them solely for rainwater.
I guess we have to sort out how to maintain a "shelf life" for the collected water- I imagine chlorination.
At present we are living in a cabin on the property and using collected water there in the summer but we don't have the diverter and the water gets pretty icky when not replenished for some time. Our area gets - if I recall about 20 inches of total precipitation/year.
Another thing we have looked at is a gray water recycling system (BRAC) do you have any knowledge of that? One concern there too is that with just 2 of us in the house you don't want to forget to periodically flush the toilet in the rarely used 2nd bathroom...
Thanks for your input!
Puzzle
Hi,I have been collecting material for a potential greywater recylce section on my website. The best thing I've found to date is this one:
http://www.oasisdesign.net/greywater/
I have a copy of his book, and I think he has a good approach -- keep it simple and safe. He has a very long background in the grey water reuse area, and he does not sell equipment. He also has pretty strong opinions that he does not mind sharing:) If you find any other good material, please let me know.Another book that covers the whole water thing from roof catchment to onsite gray and blackwater treatment is "Water From the Sky" by M. Reynolds. He is the EarthShip guy, and has been doing these systems for 30 years. The book is a brand new addition, and is up to date.
I think that it may only be available from their site:
http://www.earthship.org/Gary
Another factor to consider is the possibility of creating a breeding ground for legionnaires disease if the water in holding tank stands for periods of time between the temperatues of 20 and 45 degrees centegrade. If this water is then not heated to a high enough temperature to kill the legionella, then the disease could be spread to susceptible individuals through droplets from the kitchen sprayer or from the shower. Not necessarily a likely scenario, but nonetheless a possible one...
Hi Casey,
Legionnaires, hmmm that would be fun!
I am told that the trucked in city water has a shelf life of 9 months, but sure worth it to keep an eye on things!
Thanks
Puzzle
No profile info - where do you live? An air to air heat pump may work for you unless you are at 12,000 ft just outside Glacier Park or Norhtern MN.
Alberta, Canada.
I guess I mistakenly used the term geo thermal when what I should have said was "ground source". Don't know if this makes a difference.
Thanks
If the cisterns are actually buried in the ground it could work to a degree. But probably not well enough to be worthwhile.
If the cisterns can be reasonably well insulated an alternative is to turn them into heat storage tanks. You can heat them with off-peak electricity, eg, then use hydronic heating. Or use an air source heat pump to pump heat INTO the tanks during the day (when temps are high and the heat pump efficiency is highest), then use the heat at night.
(Some commercial buildings in the US do the opposite -- freeze water overnight and then use it for cooling during the day.)