22
FUTERA II INSTALLATION AND OPERATION INSTRUCTIONS
Expansion Tank
An expansion tank or other means to control thermal
expansion must be installed in the water heating system if
back fl ow prevention devices are installed.
Pump Requirements
This low-mass water heater requires a continuous mini-
mum water fl ow for proper operation. The low water fl ow
switch provided for this unit will shut down the water
heater if fl ow falls below the required minimum level. Table
5Bprovides the heat exchanger pressure drop chart and
temperature rise table. The temperature rise across the
water heater must never exceed 35°F, 19.4°C.
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. Two typical water heating systems
are shown in Figures 16 & 17.
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.
A balancing valve should be installed on the outlet side of
the water heater for purposes of adjusting the fl ow 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 5B 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 5B the fl ow 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.
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.