40
Modulating Temperature Control
This heater is equipped with a Raypak modulating
temperature control. Refer to information starting on
page 33 for information on the setting and use of this
control.
Low Water Cut-Off (Optional)
The optional low water cut-off automatically shuts
downthe 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.
Fig. 45: Modulating TemperatureControl
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 panel on the right side of the heater to
reset the gas pressure switch, as necessary. It is used
to ensure that sufficient gas pressure is present for
proper valve/regulator performance.The low gas pres-
sure switch automatically shuts down the heater if gas
supply drops below the factory setting of 3.0 in. WC for
natural gas or propane gas.
The optional high gas pressure switch connection
mounts down-stream of the gas valve. Special ports
are located on the backside of the gas valve and
accessiblefrom the front of the heater (to reset the gas
pressure switch) or through the removable access
panel on the right side of the heater (to reset the gas
pressure switch), as necessary. If the gas pressure
regulator in the valve fails, the high gas pressure
switch automatically shuts down the burner.
Operation of either the High or Low Gas Pressure
Switch will turn on an LED inside the switch housing.
Push the top of the plastic switch housing as shown in
Fig. 47 to reset a tripped pressure switch. The LED
will go out when the switch is reset.
Fig. 47: High/Low Gas Pressure Switch
Fig. 46: Low WaterCut-Off