SERIES 8800 & 8900 INSTALLATION AND OPERATING INSTRUCTIONS
Page 11
Expansion Tank
An expansion tank or other means to control thermal
expansion must be installed in the water heating system
if back flow prevention devices are installed.
Pump Requirements
This low-mass water heater requires a continuous mini-
mum water flow for proper operation. The factory
recommended circulating pump has been sized to
overcome the head loss of the water heater plus a 30
foot piping loop under normal water conditions.
Table 5 provides the heat exchanger pressure drop chart
and temperature rise table.
The temperature
rise across the water heater must never exceed 30°F
(17 °C).
CAUTION: The pump should be wired to run
continuously unless the optional pump delay is
installed. If the pump delay is used a tank-mounted
aquastat must be wired to the remote operator
terminals in the control box and adjusted so it acts
as the primary operator.
Cold Water Supply
The cold water supply must be piped to the water
heater’s outlet piping between the water heater and the
hot water storage tank. This will prevent untempered
water from entering the water heater, see the
TEMPERATURE RISE CONTROL section below. A
typical water heating system is show in Figure 5.
Temperature Rise Control
Water returned to the water heater inlet must not be less
than 110°F (43°C) or excessive condensation of the
products of combustion will damage the water heater
voiding the warranty. The method outlined below can be
employed to prevent this condition from occurring.
IMPORTANT:
A balancing valve should be installed on
the outlet side of the water heater for purposes of
adjusting the flow rate through the heat exchanger.
Thermometers are installed on both the inlet and outlet
of the water heater for determining the temperature rise
through the unit. The proper velocity through the water
heater must be maintained in accordance with Table 5
for efficient operation and long life. If the temperature
rise through the water heater is lower than
recommended the water velocity is too high. Premature
erosion of the heat exchanger will occur. Conversely, if
the temperature rise is higher than recommended in
Table 5 the flow rate is too low. Scaling and softening
of the heat exchanger will occur.
Thermostatic Mixing Valve
Water Above 140°F (60°C) can be stored at temper-
atures above 140°F (60 °C) provided that a thermo-
statically controlled mixing valve is used to temper the
hot water to an acceptable temperature before it’s
supplied for domestic use. The mixing valve
MUST
be
set to prevent a scald injury from occurring, see the
caution against scalding above. Storage of water for
domestic use above 140°F (60°C) will provide an
increased quantity of tempered water and help prevent
the growth of water born bacteria.
