PB Heat Peerless Boilers GM Series, Installation, Operation & Maintenance Manual

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B. CONTROL DESCRIPTIONS
See Figure 8.5 for locations of these devices.
1. FLAME ROLLOUT SAFETY SHUTOFF SWITCH
– A thermally activated switch located above the
burners on the inner front jacket panel. The flame
rollout safety shutoff switch will sense excessive
temperature caused by continued flame rollout and
shut down main burner gas. This is a non-recycling
switch that must be replaced once activated.
2. VENT SAFETY SHUTOFF SWITCH – A thermally
activated, manually resetable switch located on the
draft hood. If venting system becomes partially or
totally blocked, the vent safety shutoff switch will
sense excessive temperature caused by flue products
exiting the draft hood relief opening and shut down
main burner gas.
3. LIMIT CONTROL/LOW WATER CUTOFF –
A thermally activated, manually adjustable switch
located in the upper right side of boiler vestibule.
The limit senses supply water temperature and will
shut down main burner gas if the supply water
exceeds the preset temperature limit. This is a
recycling switch that will automatically reset when
the supply water falls below the preset temperature.
The control will also shut down the main burner gas
if the water level drops below the control’s location.
C. ADJUSTMENT OF GAS PRESSURE
REGULATOR
1. Using the manometer setup installed in part 8A, set
manifold pressure as follows for various gases.
a. Natural Gas - 3.5” Water Column (0.9 kPa)
b. LP Gas - 10.0” Water Column (2.5 kPa)
2. To adjust gas pressure, turn adjusting screw of gas
pressure regulator counterclockwise to decrease
pressure, clockwise to increase pressure. Refer to
Figure 8.2 for location of gas pressure regulator.
Replace the cap screw when adjustment is complete.
3. In no case should the final manifold pressure vary
more than ±0.3 inches (±75 Pa) water column from
the above specified pressures. Any necessary major
changes in the flow should be made by changing the
size of the burner orifice spuds.
4. When adjustment is complete, turn off boiler, gas
flow and electricity to boiler. Remove manometer
connection from valve and plug tapping with
plug provided. Turn utilities back on and resume
checkout.
D. CHECKING BURNER INPUT
1. Refer to rating label mounted on the jacket top panel
to obtain the rated BTU (kW) per hour input. In no
case shall the input to the boiler exceed the value
shown on the rating label.
2. Check input by use of the following formula [PB
Heat suggests reading meter for 2 Cu. Ft. (.05 Cu.
Meter)]:
BTU/Hr. Input=3600 x F x H
T
3600 – Seconds per hour
F – Cubic Feet of Gas Registered on Meter
H – Heat Value of Gas in BTU/Cubic Feet
T – Time in Seconds the Meter is Read
(Metric) Determine the input by multiplying
“F” – Meter Reading (Cubic Meters of Gas) times
“H” – Heating Value of Gas (Joules per Cubic
Meter). Divide by “T” – the time in seconds of the
meter reading.
Rate, Watts=F x H
T
3. As an alternative, use Table 8.1. Use the heating
value provided by gas supplier. Use a stopwatch to
record the time it takes for 2 cubic feet (.05 cubic
meter) of gas to pass through the meter. Read across
and down to determine rate.
The control will also shut down the main burner gas
if the water level drops below the control’s location.
START-UP PROCEDURES
VALVE
(WHERE USED)
AUTOMATIC VENT DAMPER
SHUTOFF SWITCH
VENT SAFETY
GAUGE
GAS VALVE
FLAME ROLLOUT SWITCH
PILOT (NOT SHOWN)
IGNITION MODULE
TEMPERATURE-PRESSURE
SAFETY RELIEF
LIMIT
Figure 8.5: Control Locations