RBI LCD Series Installation & Operation Manual page 20

Page 20
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.
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 shown in Figure 14 and 15.
Pump Requirements
This low-mass water heater requires a continuous
minimum water flow for proper operation. The low water
flow switch provided for this unit will shut down the water
heater if flow falls below the required minimum level.
Table 8A provides the heat exchanger pressure drop
chart and temperature rise table.
Temperature Rise Control
Water returned to the water heater inlet must not be less
than 125°F, 52°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.
LCD INSTALLATION AND OPERATION INSTRUCTIONS
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 8B 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 8B the flow rate is too low. Scaling
and softening of the heat exchanger will occur.
Thermostatic Mixing Valve - Water Above 140°F, 60°C
Water can be stored at temperatures above 140°F,
60°C provided that a thermostatically 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.