SECTI
ON
3
: O
PER
AT
ION
26
H2O BOILER
HC SERIES IOM Manual
All units are factory assembled with Low Water Cut Off, ASME pressure relief valves (HV
stamp), pressure gauges, high temperature limit cut off, gas pressure switch, air pressure switch,
drain valves and vent valves. Flame sensors provided are either flame rod or UV sensor.
In addition to standard controls and safety devices provided with the boiler, compliance with
ASME CSD.1, IRI and FM codes and requirements are available.
3.1
Sequence of Operation
3.1.1
Safety Loop
A) Components
Referring to section 1.3, for a description, and Figure 13, Control System Schematic, the safety
loop includes the following components:
High temperature cut off switch
Operating temperature switch
Low water cut off switch
Low gas pressure switch
Air Pressure Switches
Flow Switch
B)
Remote Enable/Disable
Every boiler/water heater is fully tested at the factory prior to shipment. When the unit is
tested at the factory, a “jumper” is placed between terminals identified as “Remote
Enable/Disable” (see Figure 13). If BMS is used, this jumper should be replaced by wires
from the BMS. In the absence of a BMS, the operation of the unit is governed by the
Siemens temperature controller.
3.1.2
Pre-Purge
Once the blower starts operating, the air pressure switch will close. This switch has
been factory adjusted such that when the blower reaches its minimum frequency it
will close.
WARNING:
Do not bypass any of the
instruments in the safety loop.
Doing so may cause serious
damage to the unit and its
surroundings.
D-VAC Sales Inc. Email: dmann@dvachvac.com Tel: (516) 256-3131 www.dvachvac.com
