Question:

Sometime this summer I hope to begin building solar water heater energy savings some log cabins at our = children=B9s farm camp. I would like include some solar energy features in = these cabins. = One system I am interested in is a solar water heater, to be used both = for heating water for baths and also possibly providing warmth in = certain parts of the house during the day or to a hot tub, etc.  = I would like to use long coils of black hose as the primary collector. = The problem is that in a cold climate, we are in NE Poland,  the water = can freeze in the pipes during the winter. Most systems compensate for = this by an elaborate and expensive dual (alcohol-water) system or an = expensive insulated glass system. I would like to do with with a simpler = system, and my idea is to place the absorption coils inside the house, = in a sera (glass sun porch) attached to the south end of the house. The = porch would not be heated as thoroughly as the rest of the house, just = keep above freezing during the winter, unless the sun warmes it further.  = Another idea is to use as the primary heat absorbing coils, a black = plastic hose that could handle the expansion that would occur when the = water froze. In this case, only the pump would have to be protected from = freezing by keeping it indoors. = Further, I would like to pump the water in this system with a low = voltage water pump that could be connected directly to a set of solar = cells without any intervening battery. After all there is no sense = pumping water when there is no sun. Does such a pump exist?  Finally, is there any reason why the system shouldn=B9t drain from the = collector coils whenever the system shuts down, thereby providing = further protection from freezing? Using one, or a combination of these ideas, I would hope to be able to = construct a very inexpensive system. Can anyone suggest how much and what kind of hose would be required for = such a system? Are there solar water heater energy savings charts available for calculating this? Can anyone recommend a good book on this subject? Is there anyone who has any experience with this sort of system. What = problems might you foresee? And does anyone know of a pump that could be = driven directly from solar cells without intervening batteries or = electronics? Finally, is there an FAQ for this group? Any comments would be appreciated. Dale

Response:

One system solar water heater energy savings I am interested in is a solar water heater, to be used both = for heating water for baths and also possibly providing warmth in = certain parts of the house during the day or to a hot tub, etc. = Generally, it is very difficult to space heat from active solar

heating since the solar energy supply ( daytime & summer ) is out of phase of the demand ( nightime & winter ). Whereas it is striaght- forward to supply domestic hot water since the heat can be stored easily and the demand is more in phase with supply. I have fitted space-heating from solar water heating but only as excess heat-dumps for drying clothes which automatically cut in when the solar store reaches 70 C. I would like to use long coils of black hose as the primary collector. = A similar principle is used by a few commercial manufacturers in the

U.K. for swimming pools. However an unglazed collector is only suitable for sub 30 C. water temperatures and become wildly ineffecient at normal domestic bath temperatures. These are mainly direct systems and occasionally of the drain-back type. – Hide quoted text — Show quoted text -The problem is that in a cold climate, we are in solar water heater energy savings NE Poland,  the water = can freeze in the pipes during the winter. Most systems compensate for = this by an elaborate and expensive dual (alcohol-water) system or an = expensive insulated glass system. I would like to do with with a simpler = system, and my idea is to place the absorption coils inside the house, = in a sera (glass sun porch) attached to the south end of the house. The = porch would not be heated as thoroughly as the rest of the house, just = keep above freezing during the winter, unless the sun warmes it further.  =

Technical problems here may include any flexible pipes collapsing from negative pressure if a pump is used depending on hight levels. Also how are you supporting the pipes and at what inclination to the horizon. If horizontal, you will need a glass roof to get realistic performance. Another idea is to use as the primary heat absorbing coils, a black = plastic hose that could handle the expansion that would occur when the = water froze. In this case, only the pump would have to be solar water heater energy savings protected from = freezing by keeping it indoors. =

Interesting, but if you have a pumped system there may be problems with part freezing during a thaw. The pump may try to operate with a blocked pipe. Further, I would like to pump the water in this system with a low = voltage water pump that could be solar water heater energy savings connected directly to a set of solar = cells without any intervening battery. After all there is no sense = pumping water when there is no sun. Does such a pump exist?

Certainly does .  German manufacture, 5 Watt consumption , Impedance matched for direct operation from a PV module.

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