Fulton Vertical Electric (FT-N) Thermal Fluid (hot oil) Heater - Manual (Page 70)

Fulton Thermal Corp.*Electric Thermal Fluid Heaters Manual* Version 2010-0423
Page 70
installations have block valves at the heater to facilitate safe isolation
and cleaning of the sensing line.
i) Improper switch setting
1. The 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.
j) Faulty Switch
1. If pressure is verified 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.
k) High Outlet Pressure Switch
1. All N-Model heaters have a High Outlet Pressure Switch. This is a
normally closed switch that opens with excessive heater outlet pressure.
2. The purpose of the High Outlet Pressure Switch is primarily to protect the
heater from building too much pressure. Typical coil model heaters have
a maximum working pressure of 150 psi with 100 psi safety valve(s) on
the heater outlet manifold.
3. The High Outlet Pressure Switch should be set at 5 psi over the heater
outlet pressure as read at ambient temperature assuming that none of
the conditions mentioned below are true.
4. A tripped High Outlet Pressure Switch is an indication of one of the
following and will require the manual reset button on the switch to be
pushed:
l) An obstruction downstream of the heater
1. 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.
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). Bypass regulating valve(s) should be adjusted to equal
flow condition through users.
3. 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.