Raypak MVB 503-2003 - Manual (Page 17)

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
increase the inlet water temperature to a minimum of
120°F (49°C), thereby reducing the likelihood of con-
densation 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 120°F (49°C) and a system sup-
ply 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
fire.
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
120°F (49°C).
5. If this process does not raise the inlet water tem-
perature to 120°F (49°C) and Valve A is fully open,
then slowly throttle Valve B closed to increase the
inlet water temperature to 120°F (49°C).
*
POOL
THERMOSTAT
FROM
FILTER
TO POOL
CHEMICAL
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