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9
High Output Piping
High Domestic Hot Water Usage
When a large amount of hot water is required by a Domestic
Hot Water system, the dual coil indirect water heater can be
piped together when given the high volume needed to satisfy
the high load demands. This is achieved by piping the boiler
coil and solar coil together. This will enable heat transfer to
both the heat exchangers at the same time. This is done by
series piping or piping in parallel. A decision must be made to
choose a particular system based on the heating coil pressure
drop and the desired flows. This type of piping can be done
in a solar operation as well as with a boiler to acheive this
maximum heat transfer into the water.
Series Piping
With this style of installation, the solar / boiler supply piping
is connected to boiler water IN connection. When joining in
this operation, all fittings must be no smaller than one-inch in
size. Then, the boiler water OUT and the solar water IN are
connected. This will join the boiler and soiler coils together.
The return water is piped from the solar return to the solar /
boiler supply. See FIG. 9-1 on page 26.
For tank operation use the lower
NOTICE
bulbwell to turn the tank on and off.
SDT/SET Installation & Operation Manual
Parallel Piping
With this style of installation, both heat exchanger are used at
the same time. Solar / boiler supply piping to the solar water
IN and boiler coils will be at the same temperature at the
same time. Then, the boiler return and the solar return are
piped together again to return the water to the heat source.
See FIG 9-2 on page 27.
For tank operation use the lower
NOTICE
bulbwell to turn the tank on and off.
The two-pipe reverse return hydronic loop is more balanced
and even than the two-pipe direct return hydronic loop. Both
heat exchangers receive the same temperature of water so it is
the same as the two-pipe return, but with more advantages.
One advantage over the two-pipe system is a balanced flow of
the reverse return system. This system can have a lower
pressure drop for both heat exchangers than the two-pipe
system, and it also requires less energy.
25
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