2
Mynute
SECTION 1
DESIGN PRINCIPLE AND OPERATING SEQUENCE
1.1
PRINCIPLE COMPONENTS
●
A fully integrated electronic control board
featuring electronic temperature control, anti-
cycle control, pump over-run, self-diagnostic
fault indicator, continuous gas modulation.
●
Low-water-content, copper heat exchanger.
●
Electronic ignition with flame supervision.
●
Integral high-head pump.
●
Fan.
●
Expansion vessel.
●
Differential air pressure switch.
●
Water pressure switch.
●
Two-stage gas valve.
●
Pressure gauge.
●
Safety valve.
1.2
MODE OF OPERATION
When there is a request for heat and/or hot water
via the programmer/time clock and/or any external
control, the pump and fan are started, the fan
proves the differential air pressure switch which
in-turn allows an ignition sequence to begin.
Ignition is sensed by the electronic circuitry to
ensure flame stability at the burner.
Once successful ignition has been achieved, the
electronic circuitry increases the gas rate to 75%
for a period of 15 minutes. Thereafter, the boiler’s
output will either be increase to maximum or
modulate to suit the set requirement.
When the appliance reaches the desired
temperature the burner will shut down and the
boiler will perform a three-minute anticycle (timer
delay). When the request for heat and/or hot
water has been satisfied the appliance pump and
fan may continue to operate to dissipate any
residual heat within the appliance.
1.3
SAFETY DEVICES
When the appliance is in use, safe operation is
ensured by:
●
a water pressure switch that monitors system
water pressure and will deactivate the pump,
fan, and burner should the system water
pressure drop below the rated tolerance;
●
a high limit thermostat that over-rides the
temperature control circuit to prevent or interrupt
the operation of the burner;
●
a differential air pressure switch that checks the
operation of the fan and flue thereby allowing
safe operation of the burner;
●
a safety valve which releases excess pressure
from the primary circuit;
●
burner temperature control.
Fig. 2
Expansion
vessel
Main Heat
Exchanger
gas
return
flow
Burner plate
Auto air
vent