Solar Thermal Information

10
single water plate, measuring 24 inches high and 72
inches long, has a heat output of 8447 Btu/hr based
on the reference conditions of 180ºF average water
temperature and 68ºF room air temperature. Using
the formula in figure 3-8, the correction factor with an
average panel water temperature of 110ºF and room
temperature of 68ºF is:
The estimated heat output at the lower water temperature
is thus:
This example demonstrates that systems limiting the
supply water temperature to 120ºF to retain good
performance of the solar collectors often require
substantially larger panel radiators compared to systems
with conventional heat sources that often supply much
higher water temperatures.
When panel radiators are used in a solar combisystem,
they should be piped in parallel. Ideally, each panel
radiator is served by its own supply and return piping. A
manifold-based distribution system, as shown in figure
3-9, uses small diameter PEX or PEX-AL-PEX tubing to
supply each radiator. Tube sizes in such systems varies
from 3/8-inch to 5/8-inch depend on flow rate and head
loss allowances. This type of distribution system is well
suited for solar combisystems and is shown in several
subsequent schematics.
10" high 1491 2247 3373 4498 5995 6745
24" high
3153 4750 7127 9500 12668 14254
20" high
2733 4123 6186 8245 10994 12368
16" high
2301 3455 5180 6907 9212 10363
10" high
2191 3304 4958 6609 8811 9913
24" high
4531 6830 10247 13664 18216 20494
20" high
3934 5937 9586 11870 15829 17807
16" high
3320 4978 7469 9957 13277 14938
24" high
1870 2817 4222 5630 7509 8447
20" high
1607 2421 3632 4842 6455 7260
16" high
1352 2032 3046 4060 5415 6091
16" long 24" long 36" long 48" long 64" long 72" long
length
16" long 24" long 36" long 48" long 64" long 72" long
16" long 24" long 36" long 48" long 64" long 72" long
1 water plate
3 water plates
2 water plates
height
1 water plate panel thickness
2 water plate panel thickness
3 water plate panel thickness
Heat output ratings (Btu/hr)
at reference conditions:
Average water temperature in panel = 180ºF
Room temperature = 68ºF
temperature drop across panel = 20ºF
figure 3-7
For example: Figure 3-7 indicates that a panel with a single water plate,
measuring 24inches high and 72 inches long, has a heat output of 8447 Btu/hr
based on the reference conditions of 180ºF average water temperature and
68ºF room air temperature. Using the formula in figure 3-8, the correction
factor with an average panel water temperature of 110ºF and room
temperature of 68ºF is:
CF = 0.001882 110 − 68
( )
1.33
= 0.271
The estimated heat output at the lower water temperature is thus:
Output = 0.271
( )
× 8447 = 2289 Btu / hr
This example demonstrates that systems limiting the supply water temperature
to 120ºF to retain good performance of the solar collectors often require
substantially larger panel radiators compared to systems with conventional heat
sources that often supply much higher water temperatures.
When panel radiators are used in a solar combisystem, they should be piped in
parallel. Ideally, each panel radiator is served by its own supply and return
piping. A manifold-based distribution system, as shown in figure 3-9, uses small
diameter PEX or PEX-AL-PEX tubing to supply each radiator. Tube sizes in such
systems varies from 3/8-inch to 5/8-inch depend on flow rate and head loss
For example: Figure 3-7 indicates that a panel with a single water plate,
measuring 24inches high and 72 inches long, has a heat output of 8447 Btu/hr
based on the reference conditions of 180ºF average water temperature and
68ºF room air temperature. Using the formula in figure 3-8, the correction
factor with an average panel water temperature of 110ºF and room
temperature of 68ºF is:
CF = 0.001882 110 − 68
( )
1.33
= 0.271
The estimated heat output at the lower water temperature is thus:
Output = 0.271
( )
× 8447 = 2289 Btu / hr
This example demonstrates that systems limiting the supply water temperature
to 120ºF to retain good performance of the solar collectors often require
substantially larger panel radiators compared to systems with conventional heat
sources that often supply much higher water temperatures.
When panel radiators are used in a solar combisystem, they should be piped in
parallel. Ideally, each panel radiator is served by its own supply and return
piping. A manifold-based distribution system, as shown in figure 3-9, uses small
diameter PEX or PEX-AL-PEX tubing to supply each radiator. Tube sizes in such
systems varies from 3/8-inch to 5/8-inch depend on flow rate and head loss