re: baseboard radiator usage
27 jun 2003
>besides the obvious use in the home, can baseboard radiator piping (with the
>attached fins) be used in a solar system? i know most solar collectors use
>a lateral fin to absorb more heat, but would these do any good in a diy
>project? i just found myself with a few cases of extras.
you might put a few rows at the top of a shallow sunspace behind a single
layer of r1 4' wide x 0.020" thick polycarbonate glazing with 90% solar
transmission over a south wall and circulate water with a pump and diff
thermostat, and save pump power by putting the feed and return lines below
the water level of an unpressurized heat storage tank, and put a vacuum
breaker in the feed line above the water level to allow the tubes to drain
back at night, with a 42 gallon pressurized galvanized tank in the heat
storage tank for potable hot water.
a square foot of heater with 100 f water might look like this in full sun
on a 30 f day (viewed in a fixed font):
--- ta g
|--|-->|---*---www--- 100 f
--- | --->
224 btu/h w i
30 f ------
with 50% solar collection efficiency, i = 112 btu/h, so ta = 142 f and
g = 112/(142-100) = 2.7 btu/h-f. the fin tube has a thermal conductance
of about 4 btu/h-f per linear foot. an 8' tall sunspace might have 2.7x8/4
= 5 rows of fin tube near the top with some black paint on the sunny side.
ventilation holes at the top and bottom of the sunspace could provide some
heat for the house at the same time. the upper hole might have an automatic
foundation vent or a thermostat and motorized damper for room temp control.