First off I would go with the largest heater that
you can fit in the space, 50 or 75gal. Because of
your altitude you will loose a lot of btu's just
because a simple lack of oxygen. The plumber who
hooks up your gas and sets up your appliance to
safely burn at that altitude will tell you that also.
You must temper the water to use it to heat the
slab, also keep the slab water seperate from the
domestic hot water. The temperature of the slab
water should be less than 110 degrees F, this will
prevent hotspots on the slab. To do this we usually
use a heat exchanger and two pumps. One pump circulates
water through the heater and through the heat
exchanger, the other pump circulates water through
the slab, past an expansion tank (closed system requirement),
into the bypass/heat exchanger piping arrangement.
The bypass on the heat exchanger can be a fancy
three way auto valve, but a ball valve works the
best, as it does not need replacing every year
like the other. On the type of water heater, I DUNNO!
We use John Woods up here in Canada, why? because
we have them to be compatible with the type of
water we have in the area. Talk to your neighbours
what kind do they have and how long has it lasted?
Once you decide on a dependable brand that is available
in your locale, very important as you don't want
to have to be waiting for special order parts in winter,
come back here, Terry has links to water heater manufacturers
and I believe most if not all are now offering the
energy efficient models with the pvc vent. I have a
drawing I will post at the url below, just give me a minute or two.....Lou

• Lou's Plumbing/Gasfitting-Board

• Re: Domestic hot water heater for radiant heat system GStrohl 01:55:45 8/15/99(0)