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H2O BOILER
HC SERIES IOM Manual
3.1.5
Continuous Operation
The unit continues to operate at low fire for as long as the outlet (discharge) temperature remains
higher than the desired temperature- with respect to the differentials -, and lower than the
maximum operating temperature; both being set on the temperature controller. The temperature
sensor installed on the outlet manifold continuously measures the discharge water temperature.
Signals from this sensor are sent to the temperature controller. As soon as the discharge water
reaches the desired temperature (set on the controller by the owner), the process is reversed and the
input is decreased so that discharge water remains at constant temperature. This throttle (load
tracking) process continuously takes place through increase or decrease in the air/gas mixture
(opening/closing of the butterfly valve and air damper), thereby ensuring water is always supplied
at
1
C of the desired operating (discharge) temperature.
If the outlet water temperature reaches the maximum operating temperature, the boiler/water heater
will shut down and goes into the standby mode. The unit will automatically re-start when the
water temperature drops below the operating set point minus the differential temperature.
NOTE:
If as a result of mal-functioning of the temperature controller the
discharge water temperature increases above that of the high limit
temperature switch, the unit will automatically shut down and will not
re-start until said switch is manually re-set.
WARNING:
Exceeding the maximum allowable gas manifold pressure could result in
over-firing of the unit and may cause permanent damage to the unit.
NOTES:
Air and gas flow rates are factory adjusted for optimum combustion
quality. Note that these settings may vary slightly at different site
conditions (calorific value of gas, duct length, etc.).
After installation is completed, using a gas analyzer, the CO and O
2
contents of the exhaust gases should be re-checked to ensure their
compliance with those achieved at the factory and reflected in the test
report provided to your local
H2O Boiler
representative.
IF adjustments to the factory settings of air and gas flows are made,
ensure that the manifold gas pressure does not exceed the pressure
specified on the boiler label.
D-VAC Sales Inc. Email: dmann@dvachvac.com Tel: (516) 256-3131 www.dvachvac.com