HTP SSC-119SE - Manual (Page 24)

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LP-200 REV. 3.25.14
I. BOILER BACK-UP HEAT EXCHANGER
CONNECTION (SB MODELS ONLY)
The boiler heat exchanger connections are located in the
front of the solar water heater. Use a 1” minimum pipe
size when connecting zone valves or circulators.
The inlet of the circulator must be connected to the hot
outlet side of the boiler. Be sure the direction of the arrow
on the circulator is facing toward the flow direction from
the boiler to the boiler inlet of the water heater. On the
water heater, the boiler return must be connected to the
return side of the boiler. The return from the heating loop
should have a flow check or swing check valve installed
before the return pipe from the boiler heat exchanger.
J. BOILER TANK CONTROL
Insert the boiler tank control into the control well provided
in the front of the water heater. Wire the boiler tank
control to the boiler control or relay center. Additional
equipment may be needed in order to wire the control to
the existing system. Controls also have the ability to
monitor and display solar collector temperature and upper
and lower tank temperature. See Figure 9 for installation
detail.
K. CIRCULATOR SIZING
The circulator pump must be sized for the related piping and pressure drop of the heat exchanger, and for situations specific to your
solar system. The following graph represents the pressure drop of the solar heat exchanger. Consult the solar panel manufacturer for
flow requirements to assist in pump selection.
Figure 10 – Pressure Drop through the Solar Water Heater Heat Exchanger
L. BOILER BACK-UP HEAT EXCHANGER (SB MODELS ONLY)
To assure the correct flow through the boiler back-up heat exchanger, refer to Figure 10 to correctly size the circulator to the boiler or
auxiliary heat exchanger. HTP recommends a flow rate of 1 gpm for every 10,000 BTU based on a 20
o
F temperature difference
between the supply and return of the heat exchanger.
Example: Boiler is 100,000 BTU / 10,000 BTU = 10 gpm flow rate. The heat exchanger at 10 gpm will require a circulator that will
operate at 8 feet of friction.
Figure 9 – Sensor Installation Detail