CleaverBrooks ProFire D Series - High Gas Pressure Switch; Gas Combustion Adjustment; Secondary Valve Adjustment: Gas Models D 378

Adjustments
4-4
750-204
Profire D/LND
4.4.6 — High Gas Pressure Switch
Turn the adjusting screw until the indicator moves to a pressure setting slightly above the maximum operating
gas pressure. The control will break a circuit if pressure exceeds this value. The control should be adjusted to
prevent operation with excessive gas pressure, but not at a pressure so close to normal operating pressure that
unnecessary shutdowns occur. This switch must be manually reset after tripping. To reset, allow the gas pressure
to drop and press the manual reset button.
4.4.7 — Gas Combustion Adjustment
After operating for a sufficient period of time to assure a warm boiler, make adjustments for most efficient com-
bustion. The butterfly gas valve directly controls the rate of flow. The low fire light-off setting should be regarded
as preliminary until proper gas pressure for high fire operation is established.
Determine the actual gas flow from a meter reading at high fire. With the butterfly valve open and with regulated
gas pressure set, the actual flow rate should be quite close to the required input. If corrections are necessary,
increase or decrease the gas pressure by adjusting the gas pressure regulator, following the manufacturer's direc-
tions for regulator adjustment.
When proper gas flow is obtained, take a flue gas analysis reading.
With the high fire air-fuel ratio established, the gas pressure regulator needs no further adjusting.
Recheck low fire and adjust if necessary.
Proper setting of the air/fuel ratios at all rates must be determined by combustion analysis. See Section 4.2 of
additional information.
4.4.8 — Secondary Valve Adjustment: Gas Models D 378 & 420
The secondary valve feeds gas to the inner spuds. A slot in the valve stem in relationship to the shut/open scale
on the valve indicates the blade position. In the low fire starting position, the stem slot should be positioned at
the left hand 1/4 mark and travel in a counterclockwise direction to the mid fire shut position. Continuing in a
counterclockwise direction, the stem slot should stop at the right hand 1/4 mark. This is the high fire position.
Both low and high fire positions are approximate. Adjustments to the valve should be made on the secondary
valve linkage arm. To increase the travel, move the linkage arm closer to the pivot point. To decrease the travel,
move the linkage arm away from the pivot point. The primary valve which feeds the outer spuds should be
adjusted as normal.
NOTE: Check for CO through the entire firing range.