Solar Thermal Information

22
As the tank’s temperature begins to drop, the burner fires
to maintain a suitable temperature at the top of the tank
for sustained domestic hot water delivery.
The thermal mass at the top of the tank also stabilizes a highly
zoned space heating distribution system. In figure 4-8, this
distribution system consists of a manifold station supplying
individually controlled panel radiators. Each radiator has
its own thermostatic valve to control heat output. This
allows for room-by-room zone control. A variable-speed,
pressure-regulated circulator (P2) automatically varies its
speed in response to radiator valve modulation.
USING A POOL AS A HEAT DUMP:
The system shown in figure 4-9 is an extension of antifreeze-
based system #2, and includes a provision to dump excess
heat from the storage tank to a swimming pool.
The extremely large thermal mass represented by the
pool can accept a significant amount of heat while only
raising a few degrees Fahrenheit in temperature.
This system would treat domestic water as its priority
load, routing solar-derived heat to the tank whenever
possible. The space heating portion of the system would
operate as described for antifreeze-based system #2.
If the temperature at the top of the storage tank
reached a user-selected maximum limit, the heat dump
subsystem would come into operation. In this system,
the following sequence takes place: 1) The diverter
valve routes the hot antifreeze solution returning from
the collectors to the pool heat exchanger. 2) The flow
switch detects this flow and turns on the pool filter
pump (if it is not already operating). 3) Heat is now
transferred to the pool.
Since the space heating portion of this system is unlikely to
operate during warm weather, a significant percentage of
the collected solar energy will likely be routed to the pool.
For outdoor pools not used in winter, designers must
provide a means of disabling the pool heating mode, and
direct any excess energy to an alternative heat dump.
solar collector array
TRV
TRV
TRV
TRV
TRV
TRV
outdoor
temperature
sensor
VENT
solar
circulation
station
air vent
w/ shut off
valve
flow
switch
anti-scald tempering valve
stainless steel heat exchanger
3-way motorized 
mixing valve
integral
mod/con
burner / heat
exchanger
thermostatic radiator valves
on each panel radiator
pressure-regulated
circulator
(P2)
(P1)
storage tank
manifold distribution
system using PEX or
PEX-AL-PEX tubing
panel radiator
check
valve
figure 4-8