Fulton Hopkins (HPN) Horizontal Coil Thermal Fluid (hot oil) Heater - Manual (Page 68)

© The Fulton Companies 2014
MAINTENANCE
HPN-IOM-2014-0416
SECTION 4
4-8
!
WARNING
All information in this manual is for
reference and guidance purposes,
and does not substitute for required
professional training, conduct,
and strict adherence to applicable
jurisdictional/professional codes and
regulations.
4
CAUTION
All maintenance procedures should
be completed by trained personnel.
Appropriate training and instructions
are available from the Fulton Service
Department.
 Air Switch
Remove the ¼” copper tubing from the bottom of the air switch with the fan
running. Air switch should trip the interlock circuit. Re-attach copper tubing and
reset fl ame programmer.
 Air Filter Box Switch
With heater running at high fi re, block opening to air fi lter box by 50%. Slowly close
off further until switch trips. Air fi lter switch should trip at just over 50% blockage.
Monitor combustion valves during this procedure.
 Temperature Limit(s)
Adjust set point(s) of temperature limit(s) down to a point lower than the process
variable (PV). PV is typically the current fl uid temperature at the heater outlet.
Solid-state controls will deactivate a control relay powering a set of n.c. contacts
in the interlock circuit. Analog controls will open their contacts in the interlock
circuit. Trip temperature should be within 5 degrees of PV temperature. Reset
temperature limit if reset exists and reset fl ame programmer.
 High/Low Gas Pressure Switch
 TESTING OF LOW GAS PRESSURE SWITCH
While boiler is running, increase the fi ring rate to the highest modulation rate
(usually 100 percent high fi re); increase the dial on the low gas pressure switch
keeping note of the pressure at which the switch trips and the boiler locks out.
Once the low gas pressure switch trips, decrease the low gas pressure switch
50 percent lower than the trip position (e.g., boiler trips at 10, decrease dial to
5). Once dial is set to desired range, reset the pressure switch and the fl ame
programmer and turn boiler on. Observe for proper operation.
 TESTING OF HIGH GAS PRESSURE SWITCH
While boiler is running, decrease the fi ring rate to the lowest modulation rate
(usually 0 percent low fi re); decrease the dial on the high gas pressure switch
keeping note of the pressure at which the switch trips and the boiler locks out.
Once the high gas pressure switch trips, increase the high gas pressure switch
50 percent higher than the trip position (e.g., boiler trips at 10, increase dial to
15). Once dial is set to desired range, reset the pressure switch and the fl ame
programmer and turn boiler on. Observe for proper operation.
NOTE:

High gas pressure switch may sense pressure before or after gas
butterfl y valve. This will impact testing of high gas pressure switch. In a
case where gas is sensed before butterfl y valve, use instructions above. If
sensing line is after the butterfl y valve, test the high gas pressure switch
during high fi re position (usually 100 percent high fi re). This is where the
most gas pressure will be present. In some cases, you may have to close the
ball valve after the gas butterfl y valve and the high gas pressure switch to
make it trip.