On (08 May 96) Tom Dugas wrote to All...
 TD> Let's say I set up a standard minimal off-the-grid homestead
 TD> in sunny Texas. Couple to four PV setups, 12V battery base
 TD> powered, 110V inverter for occasional use, LPG fired generator
 TD> to charge things up when cloudy/rainy days roll around or to
 TD> provide 110V when needed for large loads.
Sounds good, though 2-4 PV panels is not a lot for most climates - a
_small_ system even in the best of climates.
 TD> But what about hot-water?  Brrrrr!  I couldn't get past this
 TD> stumbling block (I'm a weenie, I like hot showers, ;-^ ) but
 TD> then I thought, hey, they make natural gas fired water
 TD> heaters, wouldn't that work off of a LPG system??
Sure, there are plenty of propane-fired water heaters available,
both tank type :( and tankless. Two of the most common demand
(tankless) makes are Paloma and Aquastar. We have an Aquastar 120
and have been quite happy with it. We pre-heat with a coil through
our woodstove and then the Aquastar does the rest when necessary.
 TD> Is a natural gas fired water heater totally without electrical
 TD> connections?  I was curious as to how the timer/switch worked
 TD> sans electricity, or would that have to be hooked up
 TD> permanently to a 110V/12V system for safety/reliability?
Good question. The demand type heaters are totally non-electrical.
And the propane tank type we had (but never used) had no electrical
connections. I'm guessing it had some sort of piezo electric
thermostat built into it. 
 TD> I tought about a large pre-heater tank that could soak up sun
 TD> rays all day and then pipe it into a smaller heater tank that
 TD> was LPG fired. Is this sort of thing practical on a small
 TD> scale, let's say 250-400 Gallons?
I think the idea of tank water heaters is somewhat flawed. Why use
the energy to hold a lot of water at that temperature when you can
just heat what you need when you need it with a demand heater? OTOH,
preheating with solar or wood makes sense, since there is no fuel
outlay to speak of.
Take care,
                        Ian
... A boy on ice is SELDOM in hot water.                                      
 
--- PPoint 1.96
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