Operating instructions

19
Part Number 550-142-784/0812
GWA Series 2 Gas-Fired Water Boilers – Boiler Manual
8 Department of Energy – Compliance
9 Sequence of operation – spark-ignited pilot boilers
Follow all procedures given in this manual
and operating instructions when operating
the boiler. Failure to do so could result in
severe personal injury, death or substantial
property damage.
1. Standby: Withnocallforheat, the ventdamperand
circulator are de-energized. No gas flows to pilot or main
gas valve.
2. Call for heat (thermostat circuit closes):
a. While attempting to satisfy the heat demand, the
control module monitors the boiler temperature
changes via the temperature sensor and determines
whetherornottheavailablehotwaterwillsatisfythe
demand,onlyrunningthecirculator.Ifadditionalheat
isneeded,thesequencecontinues.WhenDHW(if
used)callsforheat,sequenceaboveisbypassed.
b. Ventdamperandcirculatorenergizedifpilotstatus
acceptable.Vent damper drives open.When vent
damper end switch makes circuit, ignition control
begins pilot ignition attempt.
c. Ignitioncontrolchecksforfalseamesignal:Ifigni-
tion control senses pilot signal when no pilot gas
should be present, control will lockout,requiring
reset procedure as given in Figure 14, page 20.
3. Pilot ignition: Control module sparks the pilot and
opens pilot valve in main gas valve.
a. Ifpilotdoeslightandcontrolmodulesensesame
current,sparkgeneratoristurnedoffandmainvalve
opens.
b. Natural Gas - Ifpilotdoesnotlightwithin15seconds,
pilotvalveisclosedandsparkgeneratoristurnedoff.
Controlmodulewaits5minutes,thenattemptstoignite
pilotagain.Thiscyclewillcontinueindenitelyifpilot
ignition control does not sense pilot flame.
4. Main burner operation:
a. Controlmodulemonitorspilotamecurrent.Ifsignal
islost,mainvalvecloses,sparkgeneratoractivates
and sequence returns to step 4.
b. Ifpowerisinterrupted,controlsystemshutsoffpilot
and main gas valves and restarts at step 1 when
power is restored.
c. Intheeventthelimitcontrolshutsdowntheboiler—
The control module closes the main gas valve, but
keepsthecirculatoroperatingandtheventdamper
open.
This boiler is equipped with a control system that automatically adjusts a time delay period to turn on the boiler
during a call for heat. This is accomplished by circulating available hot water in the system while measuring
water boiler water temperature changes. The control calculates a suitable delay based on temperature measure-
ments and turns the boiler on only after it determines that the demand for heat cannot be satisfied with the
available hot water,
Due to the wide variety of controls used in boiler installations, this control is also equipped with an adjustment
for the calculated time delay period (ECONOMY ADJUST). In the MIN position, the time delay is zero and the
IMPORTANT notice below must be observed:
IMPORTANT
In accordance with Section 325 (f) (3) of the Energy Policy and Conservation Act, this boiler is equipped with
a feature that saves energy by reducing the boiler water temperature as the heating load decreases. This feature
is equipped with an override which is provided primarily to permit the use of an external energy management
system that serves the same function.
THIS OVERRIDE MUST NOT BE USED UNLESS AT LEAST ONE OF THE FOLLOWING CONDITIONS IS TRUE:
• An external energy management system is installed that reduces the boiler water temperature as the heating load
decreases.
• This boiler is part of a modular or multiple boiler system having a total input of 300,000 BTU/hr or greater.
• This boiler is equipped with a tankless coil.