Low Water Cut-Off (Optional)
The low water cut-off (sales option F-10) automatical-
ly 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 low gas pressure switch connection (sales option
S1/S2) mounts upstream of the gas valve (on the inlet
flange to the gas valve) and is accessible through the
removable access panels on the front or top of the
boiler to reset the gas pressure switch, as necessary.
It is used to ensure that sufficient gas pressure is pres-
Fig. 33: High Limit (Auto Reset)
FIXED SETTING
ADJUSTABLE
SETTING
NOTE:
Adjustable limits must be set higher than the
expected outlet temperature of the unit during nor-
mal operation, to prevent short cycling and nuisance
trips.
37
Flow Switch
This standard, dual-purpose control shuts off the boil-
er in case of pump failure or low water flow. The flow
switch ships mounted and wired.
Fig. 36: Low Water Cut-Off Board
Flue Temperature Limit
The heater is equipped with a fixed setting manual
reset high limit temperature device on the vent, for use
with non-metallic vent material. The high temperature
limit is located inside the unit near the vent adapter.
The VERSA monitors the limit and displays any fault
associated with the limit on the user interface. To reset
the limit, access it and press down on the red button.
Units provided with a PVC vent connector are also
provided with a limit rated for PVC vent material. A
higher rated limit is provided when using
Centrotherm™ polypropylene venting. The limit is
removed when using Category IV stainless steel vent-
ing.
Fig. 34: Flow Switch
Fig. 35: Flue Temperature Limit
