SERIES 8800 & 8900 INSTALLATION AND OPERATING INSTRUCTIONS
Page 15
DOMESTIC WATER SUPPLY PIPING
CAUTION: Proper controls must be used to prevent
water supplied for domestic use from exceeding
130
°
F,
54
°
C
or a scald injury will occur! When
higher water temperatures are required for
appliances such as a dishwasher, a mixing valve or
some other tempering means must be installed.
Households with small children may require water
temperatures less than 120
°
F,
49
°
C
. Local codes
must be complied with!
General Piping Requirements
Ensure that the water heater is equipped with bronze
headers. Piping and components connected to the water
heater must be suitable for use with potable water. The
water heater must not be connected to any heating
system piping or components previously used with a
non-potable water heating appliance. Toxic chemicals,
such as those used for boiler treatment, are not to be
introduced into any potable water used for space
heating. If a hot water storage tank is used in the system
it must be equipped with a temperature and pressure
relief valve that complies with ANSI Z21.22 or CAN-4.4
and CAN-4.6.
NOTE: The storage tank must be located as close
to the water heater as possible to prevent excessive
head loss which will reduce flow.
Water Chemistry
The required temperature rise across the water heater
is based on water having a hardness between 8 and
18 grains per gallon with a level of dissolved solids not
exceeding 350 ppm. Water having a hardness less than
8 grains can cause excessive corrosion of the heat
exchanger. Water that has a hardness greater than 18
grains per gallon and/or a level of dissolved solids
exceeding 350 ppm will require a recalculation of the
pump size and temperature rise.
A cupro-nickel heat exchanger may also be required. The
manufacturer should be consulted when these water
conditions are encountered. See Table 7A.
CAUTION: The maximum allowable flow rate
through a water heater with copper heat exchanger
on an 8900 is 92 GPM,
5.8 L/s
and is 185 GPM,
11.7 L/s
on single pass. The cupro-nickel heat exchanger
allows for 100 GPM,
6.3 L/s
and 200 GPM,
12.6 L/s
on
single pass.
The maximum allowable flow rate through a water
heater with copper heat exchanger on an 8800 is 185
GPM,
11.7 L/s
and 370 GPM,
23.3 L/s
on single pass.
The cupro-nickel heat exchanger allows for 200 GPM,
12.6 L/s
and 400 GPM,
25.2 L/s
on single pass. See
Tables 6A and 6B.
RBI water heaters are designed to run scale free. Due
to the extreme variables of water conditions world wide
it is necessary to consider pH values and water
hardness in relationship to scaling. It is crucial to
consider these two variables when making heat
exchanger and pump selections. If local water conditions
are extreme, follow the guidelines in the Heat Exchanger
Selection Table (Table 7A) and the Pumping
Performance Table (Table 7B). Scale free operation can
be achieved by using water with a hardness between 8
and 18 and by maintaining the pH between 5 and 9.
Follow the conditions listed under NORMAL in the table.
In some areas of the country additional precautions
must be observed due to unusual characteristics of the
local water supply. Call the nearest RBI representative
for details.
To properly size the pump a grain hardness and pH test
must be taken at the installation site before the order is
placed. Proper pump sizing will improve heater
performance and help ensure heater longevity.
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.
