FT-C Vertical Electric Thermal Fluid Heater Manual 12 2013 ISSUE 1
4. Once the system has been brought up to full operating temperature, assuming that
the entire system has seen ow, there should be no further occurrence of low heater
contamination apart from possible heat exchanger failure.
g)
1. 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
ow to make the pressure switch. Check the thermal uid system for proper operation of
control valves.
h)
1. 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.
j)
1. The Low Inlet Pressure Switch should be set at 0.35 barg less than the pressure read on
the heater inlet pressure gauge at full operating temperature of the system.
k)
1. If the pressure is veried and reads correctly above the set point on the switch and the
sensing line to the pressure switch is open, the pressure switch is faulty. Replace the
switch, set for the desired set point and test for proper operation.
l)
1. All C-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 heaters have a maximum working pressure of
10.34 barg with 6.9 barg safety valve(s) on the heater outlet manifold.
3. The High Outlet Pressure Switch should be set at 0.35 barg 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 to be pushed:
m)
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 the 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 ow 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.
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