Operating Limit Temperature Control: Hot Water; High Limit Temperature Control: Hot Water; Low Water Cutoff Devices: Steam And Hot Water; Combustion Air Proving Switch - CleaverBrooks CBEX Elite Operation And Maintenance

6.5 — Operating Limit Temperature Control: Hot Water
6.5 — Operating Limit Temperature Control: Hot Water
Set the "cutout" (burner off) temperature on the scale by inserting a screwdriver through the cover opening to
engage the slotted head adjusting screw. The "cut-in" (burner on) temperature is the cutout temperature minus
the differential.
6.6 — High Limit Temperature Control: Hot Water
Set the "cutout" (burner off) temperature on scale using the adjusting screw. The control will break the circuit
and lockout on a rise in water temperature above the setting. The setting should be sufficiently above the operat-
ing limit temperature to avoid unnecessary shutdowns. On a 30 psig hot water boiler, the setting is not to exceed
240º F. The control requires manual resetting after tripping on a temperature increase. To reset, allow the water
temperature to drop below the cutout setting less the differential, and then press the manual reset button. Failure
to do this will disallow restarting.
6.7 — Low Water Cutoff Devices: Steam and Hot Water
6.8 — Combustion Air Proving Switch

Combustion Air Proving Switch

FIGURE 6-3.
750-368
CBEX Elite 100-1200 HP
No adjustment is required since LWCO controls are preset. However, if the water
level is not maintained, inspect the devices immediately and replace as required.
Low Water Cutoff
FIGURE 6-2.
Air pressure against the diaphragm actuates the switch which, when made, com-
pletes a circuit to prove the presence of combustion air. since the pressure of the
combustion air is at its minimum value when the damper is full open, the switch
should be adjusted under that situation. It should be set slightly below the mini-
mum pressure, but not too close to that point to cause nuisance shutdowns.
The run/test switch on the program relay should be set to "Test." Turn the burner
switch on. The blower will start (provided that all limit circuits are completed)
and the programmer will remain in the low-fire (damper closed) portion of the
pre-purge.
6-5