CleaverBrooks 4WI, Руководство по эксплуатации, обслуживанию и запасным частям

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750-211 (revised 2009)
Promethean Boilers, Model 4WI Manual 2-17
2.13 — Oil Fuel Flow: Heavy Oil
Fuel oil is delivered into the system by a supply pump which delivers part of its discharge to the oil burner. Excess
oil is returned to the oil storage tank through the fuel oil relief valve and oil return line. Normally, the pump oper-
ates only while the burner is in operation, although a positioning switch is often provided so that either continuous
or automatic pump operation can be obtained.
The oil flows through a fuel oil strainer to prevent any foreign material from flowing through the control valves
and nozzle. The fuel oil controller contains in a single unit a metering valve, a regulator, and a gauge required to
regulate the pressure and flow of oil to the burner. The adjustable regulator controls the pressure. To assist in the
regulations, back pressure is created by an orifice nozzle located in the oil return line immediately downstream of
the fuel oil controller.
The programming relay energizes or de-energizes the solenoid oil valves to permit or cut off oil flow to the burner.
Two valves, operating simultaneously, are used. The valves are closed when de-energized. They cannot be opened
(energized) unless the combustion air proving switch and the atomizing air proving switch are closed. The two
switches are satisfied, respectively, by sufficient combustion air pressure from the forced draft fan and pressurized
air from the air pump.
The oil flow to the burner is controlled by the movement of the metering stem in the oil metering valve, which var-
ies the flow to meet load demands. The metering valve and the air damper are controlled simultaneously at all times
by the modulating motor to proportion combustion air and fuel for changes in load demand.
2.13 — Oil Fuel Flow: Heavy Oil
In Figure 2.17 the heavy oil fuel flow and circulating system is shown and the pertinent controls are identified.
Fuel oil is delivered into the system by the fuel oil supply pump which delivers part of its discharge to the oil heater.
The remainder of the fuel oil returns to the oil storage tank through a fuel oil relief valve and oil return line.
The combination electric and steam oil preheater is controlled by thermostats. The electric oil heater thermostat
energizes the electric heater, which is provided to supply heated oil on cold starts. The steam heater thermostat
controls operation of the steam solenoid valve to permit a flow of steam to the heater when steam is available.
A hot water boiler is equipped to heat the oil with hot water from the boiler, unless other preheating equipment is
utilized. The electric heater, which is housed separately, is sized to provide heated oil on a cold start. The hot water
thermostat controls the operation of a pump that supplies hot water to the oil heater when hot water is available.
The heated oil flows through a fuel oil strainer to prevent any foreign matter from entering the control valves and
nozzle.
The fuel oil controller contains, in a single unit, the necessary valves, regulators, and gauges to regulate the pressure
and flow of oil to the burner.
The program relay energized or de-energizes the solenoid oil valve to permit or cut off oil flow to the burner. The
oil solenoid is closed when de-energized. It cannot be opened (energized) unless the combustion air proving
switch, the atomizing air proving switch, and the low oil-temperature and any pressure switches are closed. They