Raypak MVB 504A, Installation & Operating Manual

Page: 18 / 64

18
Potable Water and Space Heating
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.
CAUTION: When this heater is used for both
potable water and space heating, observe the
following to ensure proper operation.
∆T = Temperature rise, °F
∆P = Pressure drop through heat exchanger, ft
SHL = System head loss, ft (based on heater and tank connections of no more than 100 eq. ft. of tubing)
gpm = Gallons per minute, flow rate
MTS = Minimum tubing size
*Must utilize optional cupro-nickel tubes. If over 25 grains per gallon, a water softener/treatment system must be utilized.
**Caution: For scale free operation with "Hard Water" (16-25 grains per gallon of total hardness), the operating control must NOT be set
higher than 130 F. For higher than 130 F operation, a water softener/treatment system must be utilized.
***Care should be given to prevent over-softening of the water as over-softened water can become aggressive. Cupro-nickel tubes are
recommended for water softened below 5 grains per gallon.
Table G: Domestic Water Heater Flow Rate Requirements
3-4 Grains Per Gallon 5-15 Grains Per Gallon 16-25** Grains Per Gallon
T
(°F) GPM
P
(ft wc)
MTS
(in)
SHL
(ft wc)
T
(°F) GPM
P
(ft wc)
MTS
(in)
SHL
(ft wc)
T
(°F) GPM
P
(ft wc)
MTS
(in)
SHL
(ft wc)
504A 17 50 3.6 2 8.3 17 50 3.6 2 8.3 9 95 10.4 2 25.7
754A 26 50 4.0 2 8.7 17 73 7.8 2 17.3 14 90 11.4 2 25.3
1104A 21 85 11.5 2 1/2 16.2 21 85 11.5 2 1/2 16.2 15 116 19.6 2 1/2 27.8
1504A 27 94 18.4 2 1/2 24.0 24 105 22.5 2 1/2 29.3 22 115 26.5 2 1/2 34.6
2004A 29 117 32.6 2 1/2 40.9 29 117.2 32.6 2 1/2 40.9 29 117 32.6 2 1/2 40.9
SOFT* MEDIUM HARD*
MVB
Model
WATER HARDNESS
NOTE: WH units will operate to a maximum tank
temperature of 160 ° F. For temperatures required
above 160 ° 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 and install per valve
manufacturer’s instructions.
Fig. 17: WH Units - Single Water Heater with Tank
H Units - Single Boiler with Process Tank
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”
after the Tank Target temperature is achieved and as
user defined in the ADJUST menu.