Harsco Industrial P-K THERMIFIC N700, Installation & Owners Manual, Page: 40 / 64

P-K THERMIFIC
®
Gas-Fired Boiler
40
Lo-Hi-Lo (1500, 1700, 2000 Series)
This is a two stage firing arrangement with the mechanical action provided by the two stage gas valve
actuator via a vertical rod connected to the damper assembly shown below. The damper shaft is a
horizontal shaft that enters the boiler (indicated in photo). Note the slot on the end of the shaft that
indicates the position of the damper inside the boiler (i.e. horizontal is full open, vertical is closed). The
boiler is factory fire-tested and adjusted for two firing rates: Hi fire (100% of rated input) and Low fire
(60% of rated input).
Air adjustments corresponding to both Hi fire and Low fire are required. Adjust Hi fire air first, and Low
fire air second.
Adjust Hi fire as follows:
Hi fire adjustments are made with the valve actuator in the Hi fire position. While
in purge, set the flame safeguard to “TEST”. Grasp the damper rod with locking
pliers (as shown in the photo right), loosen the two allen screws (5/64") on damper
shaft, and make very small adjustment to the damper shaft position until proper
cabinet air pressure is achieved.. Retighten the allen screws.
Do not attempt to adjust the linkage or vertical rod.
Do not let go of the damper shaft during this operation.

After damper shaft adjustments are complete, adjust the Hi fire setscrew until it
just touches the definite stop and lock it with the nut.
NOTICE! Do not attempt to adjust hi fire by using the hi fire definite stop screw.
Adjust Low fire as follows:
Low fire adjustments are made with the valve actuator in the low fire position. Use
the low fire stop screw (on the left) on the definite stop bracket to obtain desired
Lo fire air and lock it with the nut.
After both adjustments are complete, return the flame safeguard to the run position and allow the boiler
to start normally.
Hi Fire
Low Fire
Damper Shaft
w/position slot
Low Fire Set Screw
Hi Fire Set Screw
Allen Screws