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Finned copper tube gas boilers & water heaters – Boiler Manual
18
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DOMESTIC WATER SUPPLY PIPING
Proper control sett ings 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. Th e water heater must not be connected to any
heating system piping or components previously used with a non-
potable water heating appliance. No toxic chemicals, such as those used
for boiler treatment, are to be introduced into the 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.
Th e storage tank must be located as close to the water
heater as possible to prevent excessive head loss which
will reduce fl ow.
Water Chemistry
Th e 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 errosion 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. Th e manufacturer
should be consulted when these water conditions are encountered.
See Table 8A.
Th e maximum allowable fl ow rate through a Dominator
water heater with copper heat exchanger is
105 GPM
,
6.6 L/s
. Th e cupro-nickel heat exchanger allows for
120 GPM
,
7.6 L/s
, see Table 8B.
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 selection. If local water conditions are extreme follow the
guidelines in the Heat Exchanger Selection Table (Table 8A) and the
Pumping Performance Table (Table 8B). 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.
