[VAC] Re: Radiant flooring

["Dr. Gerald N. Johnson, electrical engineer" <geraldj@xxxxxxxx>]

Bobb, believe me, slopping or flat glazing leaks. With the temperature
changes in this northland no gasket is perfect and there's always water
pooled at the lower edges of each pane. It can't run off past the
frames. A green house doesn't leak water because the glass panes are
shingled, but its not air tight. Double pane glass and sash with thermal
breaks keep the condensation under control.

And if there's a conventional roof and then a vertical window wall, the
insolation is down by the cosine of the sun angle compared to a glass
tilt equal your latitude for maximum insolation at the solar equinox,
but isn't as far down at the beginning of winter, tomorrow. Then there
is evidence that the vertical collector gathers more heat from snow
reflection than the sloping reflector to make up for the lack of tilt.

And what are you going to do to turn down the heat in the summer? The
sloping glass gathers summer heat better than winter heat, at a time
when you don't need or want it. The vertical glass with a bit of
overhang can essentially be shut off during the summer, automatically.
Think vertical.

My collector was glazed with two layers of plastic held up by the air
pressure from the blower. (and held down by a mesh of nylon rope). When
I didn't need the heat and hadn't removed the cover yet and didn't let
the fan run, I melted the inner layer of plastic where it touched the
collector surface. But the collector was sloping and gathered water and
rotted in a few years. So I've been there, tried those things and KNOW
they cause trouble.

And if you make that room be 24' feet long and have 8' of height of
glass you should accumulate at 100,000 btu per sunny day. 0.7 gallon of
oil. That wasn't enough in this old house to need filling the barrels
that I collected. One made a nice support for the fan and air filter box
though.

My advice is this. Make the windows for the house double paned, without
E coating, make those windows on the south side of the house about 7% of
the floor area (a magic number discovered by Thomas Jefferson) and put
the money you were planning to put into ground water heat pump and glass
wall into insulation in the walls and ceiling. Then you won't need them.
Think super insulation. The Canadian books on superinsulated houses say
its only half facetious to say the house is heated by the two occupants
and two cats. Actually it takes FOUR occupants and FOUR cats... So super
efficiency in the heating apparati is no great benefit. If you go
significantly over that 7% floor area number, the house will heat too
much during the day and cool too much during the night unless you make
the floors 6" concrete slabs topped with black slate to act as solar
absorbers. And for the price of the slate (though black concrete dye
might do nearly as well) you can buy a bit more fuel for a long time.
Solar houses with the whole southern exposure made of glass without that
storage element are not livable. This old house with 7' windows on the
south side is not nice most of the fall, winter, and spring because
those rooms overheat and the rest of the place freezes because the
thermostat is in the main room with the tall windows.

Most of the things you propose have been tried and generally found
mostly lacking. Good in theory, good some of the time and a real pain
more of the time.

So the curb side of my Caravelle needs more windows.... Where to put
them? I should have parked it with the street side south for the winter.

Gerald J.