Raypak MVB 503-2003 - Manual (Page 37)

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Fig. 38: High Limit (Manual Reset)
High Limit—Auto Reset (Optional)
This heater may be equipped with an optional adjust-
able auto reset high limit temperature device.
The optional adjustable auto reset high limit is located
inside the heater junction box. Adjust the setting to
approx. 20°F (10°C) above desired outlet temperature.
Fig. 39: Adjustable High Limit (Auto Reset)
Flow Switch
This standard, dual-purpose control, mounted and
wired in series with the main gas valve, shuts off
heater in case of pump failure or low water flow.
Fig. 40: Flow Switch
Modulating Temperature Control
This heater is equipped with a Raypak modulating
temperature control. Refer to information starting on
page 30 for information on the setting and use of this
control.
Fig. 41: Modulating Temperature Control
Fig. 42: Low Water Cut-Off
Low Water Cut-Off (Optional)
The optional low water cut-off automatically shuts
down the burner whenever water level drops below the
level of the sensing probe. A 5-second time delay pre-
vents premature lockout due to temporary conditions
such as power fluctuations or air pockets.
High & Low Gas Pressure Switches
(Optional)
The optional low gas pressure switch connection
mounts upstream of the gas valve (on the inlet flange
to the gas valve) and is accessible through the remov-
able access panels on the rear of the heater to reset
the gas pressure switch, as necessary. It is used to
ensure that sufficient gas pressure is present for prop-
er valve/regulator performance. The low gas pressure
switch automatically shuts down the heater if gas sup-
ply drops below the factory setting of 3.0 in. WC for
natural gas or propane gas.