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17
The MVB must be equipped with a field-supplied ex-
ternal pump and bypass arrangement. This
arrangement blends outlet water with the inlet water to
i
ncrease the inlet water temperature to a minimum of
105°F (40°C) for Pool Heater (P and WHP) versions
a
nd 120°F (49°C) for Hydronic Heating (H7) or
Domestic Hot Water (WH1) versions, thereby reducing
the likelihood of condensation forming on the heat
exchanger. The pump also serves to circulate water
through the heater from the main system piping.
To complete the installation of the pool heater, the pool
thermostat must be installed in the main return water
line, upstream of the heater. This will ensure that the
heater will be energized at the right time.
Adjustment of the manual bypass valve is critical to
proper operation of the heater. The manual bypass
valve should be adjusted to achieve a minimum inlet
water temperature of 105°F (40°C) for Pool Heater (P
and WHP) versions and 120°F (49°C) for Hydronic
Heating (H7) or Domestic Hot Water (WH1) versions
and a system supply water temperature below 140°F
(60°C). When starting with a cold pool, make initial
adjustments. Make final adjustments when pool water
approaches desired temperature.
The use of a bypass is required for proper operation in
a pool heating application. Use the following instruc-
tions to set the manual bypass:
CAUTION: Power to the heater should be
interlocked with the main system pump to make sure
the heater does not fire without the main system
pump in operation. Improper flow control can
damage the heater. Uncontrolled flow (too high) or
restricted flow (too low) can seriously damage the
heater. Follow these instructions to make sure your
heater is properly installed.
1. Turn on pump.
2. Turn on heater and wait until heater goes to full
f
ire.
3
. With the heater operating at 100% firing rate, set
Valve A (the bypass) to
1
⁄2 open position, and Valve
B to fully open position. See Fig. 16.
4. Adjust Valve A until the inlet water temperature is
105°F (40°C) or 120°F (49°C) depending upon
heater type.
5. If this process does not raise the inlet water tem-
perature to 105°F (40°C) for Pool Heater (P and
WHP) versions and 120°F (49°C) for Hydronic
Heating (H7) or Domestic Hot Water (WH1) ver-
sions and Valve A is fully open, then slowly throttle
Valve B closed to increase the inlet water temper-
ature to the required temperature.
*
POOL
THERMOSTAT
FROM
FILTER
TO POOL
C
HEMICAL
FEED
Fig. 15: Single Pool Heater Application
NOTE: Opening the valve will increase the
temperature and closing the valve will decrease the
temperature.
*Maximum 4 times the pipe diameter or 12”, whichever is less.
Fig. 16: “H” Bypass Setting