07-02-14, 01:40 PM | #11 | |||||
Supreme EcoRenovator
Join Date: Mar 2009
Location: Portland, OR
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Regarding any consideration of heating, especially alternative energy heating, your efforts are best directed toward prevention of heat loss, infiltration being the first priority, insulation being the second priority, and window replacement being third.
* * * From a straight-forward point of view of cost, scenarios for doing a ground source heat pump implementation would be, in ascending cost & effort:
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As you can see, the temperature swings are greater at shallow depth, and less so as you go deeper. My bore holes are only 17 ft deep, and are greatly affected. But the variations become less as you go deeper. This next image is also important as it explains more of the story: Here you can see the time-delay of the temperature swings. So the 'thermal pulse' as I like to describe it, which is the solar heat working its way down through the ground, is somewhat lost in a shallow bore hole, as it is best, if possible to have heat demand coincide with the 'heat pulse' availability. So what I'm getting at is that a simple addition of bore hole depths is not a good model, especially at shallow depth. In your case, if you went to 60 ft depths, simple addition would be insufficient, but your error would be less than mine. The moral of the story is that you are going to need more combined depth than you are now estimating. By the way, these diagrams are from research carried out by the Oklahoma State University, and every attempt was been made by them to develop a universal understanding of ground source heating and cooling, even though local conditions may be somewhat different. SO, there is a very interesting local exception... I have learned by observation that the frequent rain falls in Portland (annual rainfall = about 34") are in fact Heat Events, and the heat from rainfall is not inconsequential. I saw, and attempted to log (with limited success) these thermal excursions. Every time there was a rainfall (pretty frequent in Portland) there was a measurable thermal pulse that worked its way down through the ground and my loop field. I would see an 'up-tick' about two days after a heavy rain. At the time, I was running my tiny heat pump 24/7, with no thermostat, and the basement temperature would rise with the peaking of the thermal pulse, and fall as it passed... definitely something was going on. I don't know anyone else who is thinking along these lines, but since we have this phenomenon going on in Portland, we should think about taking advantage of it. Quote:
There are fluid friction issues that need to be taken into account, but they are solvable. Quote:
The upshot is that we live on the debris field of all that activity. Beneath our fertile topsoil, there is sand, clay, gravel, rocks up to the size of oranges, cobbles in sizes from an orange to a football, and boulders from the size of a football to the size of a car. So, southern methods are unlikely to be successful. (* End of part 1 *)
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Tags |
air conditioner, diy, gshp, heat pump, homemade |
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