08-18-09, 08:34 AM | #11 |
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Welcome to ER the1cyrus.
For DIY heat pump info, check out this thread. http://ecorenovator.org/forum/projec...manifesto.html |
10-07-09, 12:04 AM | #12 |
Lex Parsimoniae
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I'm using geothermal to 'heat' my basement. The floor slab and the bottom
six feet of the basement walls constantly emit heat at around 65 degrees. Last winter, I never turned on the circulator pump in the basement. It stayed cool down there all winter. Right around 65-67 degrees. There is some heat loss from the oil burner and over-head pipes, but the main source of heat is the floor. I'm dying to install the 2-ton Sanyo Mini-Split. If seems like an ASHP being used for heating is kinda a hybrid. Since, it's using the heat in the air, where does that heat come from? I think there are two main sources. Solar and Geothermal. The sun heats up the air every morning. And the warmth from the earth works it's way up to the surface, also heating the air. The nice thing about the Sanyo ASHP, is the ground surface of 32 degrees is warming the air up to 32!! If the air coming into the ASHP is a smoking hot 32 degs, then my system is going to be able to crank out 25,000 BTUh of warmth. And, for a mere 2.5KWh, or 50 cents an hour until the house is all warmed up and coasting. Then it might be possible to hold 70 inside, using only 290 watts to suck in 4,400 BTUh of heat.. 6 cents an hour? Wow, I hope this thing works to spec! Maybe we could get away with 2 oil fills a year! ~~~~ Since a mini-split seems to work almost as well as a WSHP, but only cost a fraction as much, why not skip digging expensive holes and just suck the heat right out of thin air?? |
10-12-09, 12:35 PM | #13 | |
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Heat emitting basement...
Quote:
I think you might be overestimating the amount of hest coming from your basement. I know I was, before I turned off the gas furnace I really had no idea how much the furnace and heat radiating down through the floors were contributing to the basement. Here is a portion of a diagram from the book, Closed-Loop/Ground-Source Heat Pump Systems, Installation Guide, Which in my opinion should be issued to everyone at birth. The temperatures shown on the diagram are average temperatures. They are all the momentary air temperatures over several years, all averaged out to a yearly average temperature. It just so happens, and should come as no surprise, that the temperature of the earth at around 25 feet is essentially the same as the average temperature. Even though the air temperature swings day to night and day to day and season to season, the earth temperature at 25 feet stays very much the same. Obviously, you are familiar with the daily air temperature swings, well the earth temperature at the surface (like maybe .25 of an inch) also has a daily swing too, but because it has more thermal mass, the swing comes a bit later, and a bit less than the air temperature swings. In your area, the maximum earth surface swing is about plus and minus 20 degrees. As you progress deeper, the earth temperature swings come still later and are of still lower amplitude than at the surface. So, if you had no heat coming from your furnace or pipes, and no heat radiating through the floor, toward the end of the coldest months, your basement would actually be about 40 degrees, safely above freezing, but well below the 65 degrees you are measuring. ...owing to the mass of the ground around your home it might take two or three years for the accumulated heat from your warmed house to dissipate. If your foundation was very well insulated, including the basement floor, there would be less heat loss & gain and the time for the earth in contact with your insulated basement to reach equilibrium would be shorter. So, realizing all this, I really paid attention to the level of insulation that is called for here in Oregon for floors that are over enclosed, unheated areas. The spec calls for R-30, I have already put in R-13 so far, and will finish out the insulation as winter progresses. According to the charts & Information igiven in the book, an unheated basement at the end of the colder months might be around 65 degrees in southern Georgia. There the average temperatures are around 67 and the temperature swings at basemet depths are just a few degrees. Best Regards, -AC_Hacker |
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10-12-09, 01:28 PM | #14 |
Lex Parsimoniae
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Summing the monthly mean temps and dividing by 12 equals 47.916 degrees.
That's what I expected to see on the basement slab.. Woburn Weather - Massachusetts - Average Temperatures and Rainfall I'm not sure why my slab temperature seems to stay higher.. It could be the boiler is heating up the whole slab. Yes, it could be this monster! HEY! I just ran down there with my IR unit an lased the slab.. It's about 66 next to the boiler and drops down near 60 at the other end of the basement. (30 feet away). I didn't think it would have that much effect, since warm air goes up. I figured the 'waste heat' was heating the overhead beams and flooring, keeping my feet warm on cold mornings. I insulated under the top cover of the boiler last year. Before, the top was always warm to the touch. Now it's cold! I'm pretty sure the base of the boiler has nothing but about 2" of air space for insulation from the ground. Beside the thin steel rim around the edges of the base, I don't think there is very much steel in direct contact with the slab. There is no question about the heat it's putting into the slab. I wonder if the high water table is also effecting ground temperature? We have a large pond out back (70 yards away) with a swamp between us. The water table level is only a few feet below our slab. Maybe that water stays stagnate under the slab and warms up like a big hotwater bottle? Digging a ditch in the lower part of the backyard would be next to impossible, since the water is so close to the surface. No GSHP for me.. There isn't room for a system of any size anyways. Maybe I could drill some wells and get 8,000 BTU lol.?. |
10-12-09, 02:53 PM | #15 | |
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Quote:
Regards, -ACHacker |
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10-14-09, 02:10 PM | #16 |
Lex Parsimoniae
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I saw this picture on the web..
And, instantly saw a problem. When the ACs are running (in cool mode), one until is driving hot air into the unit next door! These units should have been arranged so the exhaust air didn't go into the adjacent unit.. The installers didn't read the manual... Then, the little LED above my head blinked on.. What if the owner of a Sanyo mini-split were pump 48 degree water out of a well and pipe that water into a large water-to-air heat exchanger coil, that was sitting directly in front of the Sanyo air-input?? In the summer time, pre-cooling the air going into the AC is going to help.. In the winter time when it's 20 degrees, pre-warming the air to 48 F should help too.. What do you think?? Could gizmo like this pre-heater/pre-cooler cut power usage by 10% ?? Cheers, Rich |
10-14-09, 08:02 PM | #17 | |
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Five-Stage Air Source Heat Pump...
Quote:
You are so right about those units being badly positioned. And your idea about the ground-source to air-source air-coupled heat pump is one that I'm considering testing out, now that I have the loop field... I think it would help, but with all those heat exchangers (ground-to-water, water-to-air, air-to-refrigerant, refrigerant-to-air) there are inefficiencies. Also, keep in mind that if your ground water is 48 degrees, the air coming out of the fan will not really be 48, but yes it will help. Hugh Jim Bissell suggested hacking an inverter-type mini-split air source heat pump, to bypass the air input and use water from the loop field. The inverter technology has helped the mini-split units achieve much higher levels of efficiency, but I don't know if it is being used in water source units anywhere. I know that in Europe there is a big push to use inverter technology even in central air circulation fans. I tell you, if a smallish R-22 mini-split with inverter technology falls within my evil grasp, it will most surely find itself hacked to within an inch of it's life... Water loop in and water loop out. Hee, hee, hee, hee, heeeee...... (to be read with full volume Halloween-style reverb) Best regards, -AC_Hacker %%%%%%%%%%%% |
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10-14-09, 09:02 PM | #18 |
Lex Parsimoniae
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inefficiencies be damned. You should check it out with your Sanyo..
If you could get ground temperature water in a big coil and use a very small amount of electricity pumping it, it's all gravy. Got any PV panels laying around? Are you feeling okay, you look really bad in that picture! Of course, I look scary too.. It happens when you get really old.. |
10-15-09, 09:12 PM | #19 |
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No PV panels but I do have 10 panels that are 4x8 feet to heat water, which are part of the grand strategy.
I may use them outside for solar heat collection and if any panels are not first rate, I may use them inside for radiant panels. Cut myself shaving. Happens from time to time... Best regards, -AC_HAcker |
10-15-09, 11:02 PM | #20 |
Lex Parsimoniae
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Wow 10 4x8 collectors!! That's a lot of hot water! We (a family of 3) only had 3 panels
(Novan 4x8) and they kept us in plenty of hot water. With that much collection area, it sounds like you might be doing some decent home heating. Do you have roof space or, do you plan on building ground mounts? |
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