Fulton Alliance (FT-HC) Horizontal Coil Thermal Fluid (hot oil) Heater - Manual (Page 76)

© The Fulton Companies 2012
MAINTENANCE
FTHC-IOM-2012-1001
SECTION 4
4-12
TABLE 10-A - LOW INLET PRESSURE SWITCH TROUBLESHOOTING
Problem Potential Remedy
Plugged circulation pump
strainer basket A plugged strainer will result in a decrease of 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 between 0 and -5” Hg.
If the strainer is plugged, isolate the strainer and drain that section of piping 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 pump
suction 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 is recommended to re-align the circulating
pump fi rst at ambient temperature and again when it’s at operating temperature. Alignment should be within pump manufacturers’
specifi cations
Cavitation of the circulating
pump Cavitation occurs when a pump experiences a 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
combination tank.
The most common low heater in a thermal piping system is water, which needs to be boiled out at startup or anytime new piping or
fl uid is added to the thermal oil system.
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 possible heat exchanger failure.
System is open Lack of back-pressure. If control valving is improper or pressure drop across the system is too low, the resulting minimal back-
pressure may not provide enough resistance for the fl ow to make the pressure switch. Check the thermal fl uid system for proper
operation of control valves.
Blocked Sensing Line on
Pressure Switch A blocked sensing line will give an inaccurate pressure reading to the pressure switch. A blocked line will need to be replaced or
cleaned. Most installations have block valves at the heater to facilitate safe isolation and cleaning of the sensing line. Do not attempt
when system is hot.
Improper Switch Setting Low Inlet Pressure Switch should be set at 5 psi less than the pressure read on the heater inlet pressure gauge at full operating
temperature of the system.
Switch is faulty If pressure is verifi ed and reads correctly above 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-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 5 psi over than the maximum pressure read on the heater outlet pressure gauge
during proper operation at the coldest ambient temperature expected.
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.