Fulton Vertical Electric (FT-N) Thermal Fluid (hot oil) Heater - Manual (Page 71)

Fulton Thermal Corp.*Electric Thermal Fluid Heaters Manual* Version 2010-0423
Page 71
m) Improper switch setting
1. 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.
n) Faulty Switch
1. If pressure is verified 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.
o) Flow Switches
1. Units older than mid-1993 have Flow Switches on the inlet of the heater.
These are normally open switches that close, making a micro-switch,
upon flow establishment.
2. The purpose of the Flow Switch(es) is to protect the heater from too high
of a temperature and to protect the thermal fluid from exceeding its
maximum film temperature.
Flow Switches Not Making
a) An obstruction downstream of the Flow Switch(es)
1. Any obstruction downstream of the flow switch(es) will increase the
pressure that the heater outlet sees. Any increase in outlet pressure will
result in diminished flow. This obstruction will generally result from an
improper valve setting.
2. 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).
3. Bypass regulating valve(s) should be adjusted to equal flow condition
through users. Call or e-mail Fulton for further details.
4. It may be possible that an automatic control valve has failed. If this is the
case, the valve should be replaced.
b) Plugged circulation pump strainer basket
1. A plugged strainer will result in a decrease in flow through the heater.
High vacuums developed from plugged strainers can also stress the
seals of the pump causing the pump to fail.
2. 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).
3. If the strainer is plugged, isolate the strainer and drain being mindful of
the temperature of the thermal fluid. Remove the strainer and clean with