Fulton Hopkins (HPN) Horizontal Coil Thermal Fluid (hot oil) Heater - Manual (Page 72)

© The Fulton Companies
MAINTENANCE
HPN-IOM-2014-0416
SECTION 4
4-12
TABLE 10-B - HIGH OUTLET PRESSURE SWITCH TROUBLESHOOTING
Problem Potential Remedy
An obstruction downstream of
the heater Any obstruction downstream of the heater will increase the pressure that the heater outlet sees. This obstruction will generally result
from an improper valve setting.
Observe heater outlet pressure at temperature with all users / heat exchangers calling for heat (100% user). Observe heater outlet
pressure at temperature with all users / heat exchangers not calling for heat (100% bypass). Bypass regulating valve(s) should be
adjusted to equal fl ow condition through users.
Call or e-mail Fulton for further details. It may be possible that an automatic control valve has failed. If this is the case, the valve
actuator should be inspected and possibly replaced.
Improper Switch Setting The High Outlet Pressure Switch should be set at 25 psi higher than the heater outlet pressure when the system is at operating
temperature and pressure. At no time should the switch be set above the safety relief valve set pressure.
Faulty Switch If pressure is verifi ed and reads correctly below set point on switch and the sensing line to the pressure switch is open, the pressure
switch is faulty. Replace switch, set for desired set point and test for proper operation.
TABLE 10-C - FLOW SWITCHES TROUBLESHOOTING
Problem Potential Remedy
An obstruction downstream of
the Flow Switch(es) Any obstruction downstream of the fl ow switch(es) will increase the pressure that the heater outlet sees. Any increase in outlet
pressure will result in diminished fl ow. This obstruction will generally result from an improper valve setting.
Observe heater outlet pressure at temperature with all users / heat exchangers calling for heat (100% user). Observe heater outlet
pressure at temperature with all users / heat exchangers not calling for heat (100% bypass). Bypass regulating valve(s) should be
adjusted to equal fl ow condition through users. Call or e-mail Fulton for further details. It may be possible that an automatic control
valve has failed. If this is the case, the valve should be replaced.
Plugged circulation pump
strainer basket A plugged strainer will result in a decrease in fl ow through the heater. High vacuums developed from plugged strainers can also
stress the seals of the pump causing the pump to fail.
A “Pump Suction” gauge is provided on Fulton Thermal skids to help determine when a strainer needs cleaning. Generally this point
is -2 psi (5 in. Hg).
If the strainer is plugged, isolate the strainer and drain being mindful of the temperature of the thermal fl uid. Remove the strainer
and clean with compressed air, high-pressure water or a cleaning solution. Replace and observe new heater inlet pressure.
Failed circulation pump
coupling A failed coupling will result in a decreased or no fl ow condition through the heater. The coupling can be checked by removing
the coupling guard between the pump and pump motor. The coupling should not be torn or misshapen. If the coupling needs
to be replaced, it will be necessary to re-align the circulating pump fi rst at ambient temperature and again when it’s at operating
temperature.
Cavitation of the circulating
pump Cavitation occurs when a partial vacuum presents itself at the eye of the pump impeller due to loss of head or if any low heater
fl ashes to gas at the impeller.
During this time, the pump impeller spins without actually circulating any thermal fl uid. If Fulton Thermal Corporation provided the
heater skid, loss of head to the pump is extremely unlikely with proper fl uid level in the tank.
The most common low heater in a thermal piping system is water, which needs to be boiled out at startup.
Once the system has been brought up to full operating temperature, assuming that the entire system has seen fl ow, there should be
no further occurrence of low heater contamination apart from heat exchanger failure.
Plugged coil pipe(s) If too low of a fl ow condition has occurred for too long a period of time or if the maximum operating temperature of the oil has been
exceeded, it is possible, however unlikely, that a pipe or pipes in the coil could plug with solids. If this occurs, it will be necessary to
shut down the system and clean the coil. Fulton Thermal Corporation should be consulted in this matter.