Rheem Raypak Hi Delta P902C Installation & Operating Instructions Manual page 21

Fig. 22: Single Domestic Hot Water Heater and Storage
WH – Direct DHW Configuration
When the unit is ordered as a "WH" configuration the
only application available to it is direct DHW with sin-
gle or multiple heaters (Maximum 4 heaters). The tank
temperature is controlled by the System sensor (S3).
The Boiler Pump (P1) runs during any call for heat.
The System Pump (P2) output is active whenever the
system is enabled. The Boiler Pump is delayed "off"
VERSA
after the Tank Target temperature is achieved and as
user defined in the BOILER menu.
P1
S1 S2
WATER
FACTORY INSTALLED SENSOR
FIELD INSTALLED SENSOR
Fig. 23: WH Units - Single Water Heater with Tank
H Units - Single Boiler with Process Tank
NOTE: WH units will operate to a maximum tank
temperature of 150°F. For temperatures required
above 150°F, an "H" model boiler must be used and
great care must be given to ensure water hardness
is no more than 15 grains per gallon for scale free
operation. MODE 1 should be used and configured
for setpoint operation for process heating applica-
tions.
NOTE: If local codes require a vacuum relief valve,
acquire one locally
manufacturer's instructions.
Tank
PIM
HW SUPPLY
TANK
P2
CITY
HW RETURN
and install per
Potable Water and Space Heating
CAUTION: When this heater is used for both
potable water and space heating, observe the
following to ensure proper operation.
1. All piping materials and components connected to
the water heater for the space heating application
shall be suitable for use with potable water.
2. Toxic chemicals, such as used for boiler treatment,
shall not be introduced into the potable water used
for space heating.
3. If the heater will be used to supply potable water,
it shall not be connected to any heating system or
components previously used with a non-potable
water heating appliance.
4. When the system requires water for space heating
at temperatures higher than 140°F (60°C), a
means such as a mixing valve shall be installed to
temper the water in order to reduce scald hazard
potential.
Automatic Chemical Feeders
All chemicals must be introduced and completely dilut-
ed into the water before being circulated through the
heater. High chemical concentrations will result when
the pump is not running (e.g. overnight).
S3
NOTE: High chemical concentrates from feeders
that are out of adjustment will cause rapid corrosion
to the heat exchanger. Such damage is not covered
under the warranty.
NOTE: Failure of a heat exchanger due to lime
scale build-up on the heating surface, low pH or
other chemical imbalance is non-warrantable.
CAUTION:
contaminated by corrosive chemical fumes which
can damage the heater and void the warranty.
valve
21
Combustion air must not be