[SustainableTompkins] water heating

[Joel and Sarah Gagnon]

I have been using a solar batch heater for a few years now. It serves to 
preheat the water, which then goes to a very well insulated conventional 
electric tank heater. In the summer, the water is hot enough most of the 
time that the tank heater needs to add very little heat. Kitchen and 
bathroom sinks are on either side of a common wall, with the tank almost 
directly beneath them, so there is very little waste getting hot water to 
the tap.

If I had more remote taps, I would locate the tank closest to the greatest 
use. An instantaneous electric heater (or even a small tank) at the remote 
tap would minimize water wastage, albeit at the expense of some wasted heat 
(which does heat the house, after all).

If the logistics worked, I think the water heating should be integrated 
with space heating using biofuels. I think of wood as stored solar. In the 
months of November through January, there is very little direct solar gain 
around here. Worse, the incoming water is colder, needing more heat to be 
warmed to service temperature. So, when you need it most, the sun isn't 
there. It is there, though, in indirect form in the wood I burn to heat the 
house. Moreover, my use of the stored solar is inversely proportional to 
the available direct gain, making my wood stove the ideal complement to the 
solar batch heater. The trick is to get them to work well together, which 
is difficult unless you luck out or plan a house around it.

In the early 20th century, it was common to heat hot water with a tank 
connected to the kitchen range. A convective loop of pipe adjoined the 
firebox and circulated water from the stove to the adjoining tank. A 
similar heat-transfer coil could be wedded to a woodstove to convectively 
heat water in a nearby tank, provided the tank was somewhat higher than the 
coil. Ideally, that tank could be the same tank as is heated by the sun in 
a batch heater, or, absent such a tank, it could be the tank of a 
conventional electric tank heater. Conceivably, the storage tank could be 
heated with propane of natural gas (or even oil), since the chimney is 
at  hand. The storage tank would most likely end up on the second floor 
with the woodstove on the first.

This isn't the only possible arrangement, by a long shot, but it is 
something to think about. I agree with Margaret that the ultimate solution 
may lie in generating our electricity from renewable sources, but we are a 
long way from that. If you read Mark Jacobson's web article advocating wind 
as the energy choice of choice, you may have remarked, as I did, that we 
could generate enough energy to replace all fossil fuel use in the US with 
a mere 500,000 5-megawatt wind turbines. We have the equivalent of 2000 of 
those so far. Only 498,000 to go!

Joel

  At 06:34 PM 1/27/08 -0500, you wrote:
>On Jan 27, 2008, at 6:22 PM, Ira Goldstein wrote:
>
> >   Howzabout a middle way scenario in a dwelling with say a basement,
> > 1st floor & second floor (or more): installing a single on-demand
> > heater in a location somewhere kinda equidistant from the various
> > points of use (maybe on the first floor) to eliminate an overly long
> > run and wait time to any particular use location?
>
>That would be ideal. In most houses kitchens and bathrooms are in the
>same general area. It would still take some retrofitting of hot water
>piping and a gas line would be needed and it could be power vented
>through a wall to the outside. Maybe hide it in a closet?
>
>I have day dreamed about doing this from time to time. And this
>discussion has me thinking again. But I no complaints about the
>AquaStar in the basement.
>
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