40
R/Y
BK/Y
G
W
BK
1
2
3
OFF
ON
1 - ON
2 - OFF
3 - OFF
Figure 47.
Injector Pump DIP Switches,
and Wiring
4.5. Condensate Float Switch
This heater is equipped with a condensate float switch to
prevent operation when the condensate water level is too
high. The heater shutting down from the condensate float
switch is indicative of a blocked drain or problem with the
condensate management system. The condensate float
switch is located inside the vent outlet plenum at the left
rear of the heater.
Figure 48. Condensate Float Switch
4.6. Flow Switch
This standard, dual-purpose control shuts off the heater in
case of pump failure or low water flow through the primary
loop.
Figure 49. Flow Switch
NOTE:
The wiring diagrams in this manual show all
standard options. Refer to the large wiring diagram
provided with your heater for options installed on your
specific unit(s).
4.7.
Low Water Cut-Off (Optional)
The optional low water cut-off (sales option F-10)
automatically shuts down the burner whenever the
water level drops below the level of the sensing probe. A
5-second time delay prevents premature lockout due to
temporary conditions such as power fluctuations or air
pockets.
Figure 50.
Low Water Cut-Off Board
4.8. High and Low Gas
Pressure Switches (Optional)
The low gas pressure switch (sales option S-1) mounts
upstream of the gas valve (on the inlet flange to the gas
valve) and is accessible through the removable access
panels on the side or front 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 pressure switch automatically
shuts down the heater if gas supply drops below the
factory setting of 3" WC for natural gas or propane gas.
The high gas pressure switch (sales option S-2) connection
mounts down-stream of the gas valve and automatically
shots down the heater if the gas pressure to the burner
rises above 3" WC for nat or pro. Special ports are located
on the backside of the gas valve and accessible from the
front of the heater (to reset the gas pressure switch) or
through the removable access panels on the rear 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
Figure 51
to
reset a tripped pressure switch. The LED will go out when
the switch is reset.
These safety devices will emit small amounts of fuel gas,
and must be piped to a safe discharge location outdoors,
per local code requirements.
Figure 51.
High/Low Gas Pressure Switch
