Normal Sequence Of Operation; General - UTICA BOILERS MGB Series Installation, Operation & Maintenance Manual

WARNING
!
Burn Hazard. View port on burner door may be hot.
Wear personal protection when servicing this boiler.
WARNING
!
Fire and Asphyxiation hazard. Do not attempt to
place boiler in operation if safety switches shut the
main burner gas off. Contact a qualified service
agency. Failure to follow these instructions could
result in death or serious injury.

13.1 General

Thermostat actuates on call for heat, completing circuit
1.
to control.
A. Completed circuit to control will energize the vent
damper. The circulator will be energized if the
boiler water temperature is above 125°F.
B. When the vent damper is fully open the damper
end switch completes the circuit to ignition system,
ignition takes place.
C. Circulator will activate if temperature is 125°F or
more.
In event the boiler water temperature exceeds high
2.
limit setting on the boiler mounted high limit control,
power is interrupted between control system and
ignition system.
Figure 13-1 Blocked Vent Safety Switch, Roll-out
Safety Switch (Front Panel Removed)
Flue
Inspection
Cover
Hydrolevel
Control
Ignition
Control
Burner
Door
Gas
Valve
Igniter
Burners

13 - NORMAL SEQUENCE OF OPERATION

A. Power remains off until boiler water temperature
drops below high limit setting.
B. Circulator continues to operate under this condition
until thermostat is satisfied.
In event the flow of combustion products through the
3.
boiler venting system becomes blocked:
A. Blocked vent safety switch shuts main burner gas
off.
B. If boiler flue-way becomes blocked: flame rollout
safety switch shuts main burner gas off. See Figure
13-1.
2-Zone Capability: The Hydrostat IC is equipped with
4.
a second zone for use with a 120-volt circulator. This
zone is factory set to function with an indirect water
heater for domestic hot water (DHW). The control
allows the boiler to run up to high limit setting to
satisfy calls from this zone. The control will allow the
Smart DHW Priority feature to prioritize domestic hot
water. The second zone can also be used for a heating
zone – in which case it should not be prioritized. See
Zone 2 settings in the Hydrolevel Manual provided with
your boiler.
If either of these condition A or B exist:
Do not attempt to place boiler back into operation.
Contact certified service agency. Do Not jumper
safety switch(s).
For detailed sequence of control, see Appendix A.
View Port
Base
28
Blocked Vent
Safety Switch
Rollout Switch
PN 240012785 Rev. C [11/15/2020]