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Controls – All basic controls and terminals are located in
an integral ventilated control cabinet, factory wired and
functionally tested. Controls include fuses with 200,000
ampere interrupting capacity, magnetic contactors UL listed
for 100,000 cycles, 120 volt control transformer with
primary and secondary fuses, step controller which recycles
to zero on power failure, pilot light for each heating step,
control circuit toggle switch. Note: On units with 4 steps or
less, a multistage thermostat may be supplied instead of
step controller.
Modulating Sequence Controller – Controller consists of
an
electronic
step
controller
temperature indication from a sensor mounted in the
vessel. Each step controls one or more contactors to
energize heating elements. The controller will turn on the
elements gradually at preset intervals to prevent power
surges. Progressive sequencer option provides first on/first
off control for extended life of contactors and heating
elements.
To prevent a power surge after power interruption, the
controller will reset automatically to the "OFF" position
when power is restored. Normal sequencing then stages
the heating elements in accordance with thermostat
requirements.
OPERATION & CONTROLS
which
receives
water
CONSTRUCTION
Gauges – Pressure and temperature gauges are mounted
on control cabinet front panel. Gauges indicate working
pressure and temperature of the boiler.
Safety Valve – An ASME pressure relief valve or pressure
and temperature relief valve is furnished to protect the unit
against excessive pressure. Normally set at 10 psi or 10%
above boiler working pressure, whichever is greater.
High Limit Cutout – Shuts boiler down by de-energizing
the control circuit in the event of an overheating condition.
Manual reset high limit is standard. Automatic reset limit is
optional and is set below manual reset.
Low Water Cut-Off – In the event of a low water condition,
interrupts control circuit to protect elements from damage
caused by exposure and overheating. Includes external
manual reset.
Optional Accessories – Optional built-in or remote
accessories may be included as called for by job
specifications.
Instructions
servicing of these accessories are supplied with the unit.
3
covering
adjustment
and
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