Fulton Vertical Electric (FT-N) Thermal Fluid (hot oil) Heater - Manual (Page 75)

Fulton Thermal Corp.*Electric Thermal Fluid Heaters Manual* Version 2010-0423
Page 75
Call For Heat
a) The call for heat circuit is the circuit that enables burner operation. Fulton Thermal
Corporation has used a variety of Temperature Controllers to act as the Call for Heat.
b) Generally these controls work in combination with a control relay. When the Temperature
Controller calls for heat, a signal is sent to the coil of a control relay that closes a
normally open set of contacts in series with the burner circuit.
c) When the call for heat is met, the signal is removed and the contacts return to their open
state. Situations that may interfere with the Call for Heat circuit include the following:
1. Programming problem
a. Fulton has a general program for each of the temperature
controllers we have used over the years. Compare your current
temperature controller program to Fulton's general program.
b. See the back of this section for general programming sheets for
standard Fulton heaters.
c. Make changes as necessary. Contact Fulton service department
with any questions.
2. Temperature controller failure
a. If the temperature controller is calling for heat but is not putting
power on the output to the control relay, the relay will not close
the normally open contacts and the heater will remain disabled. If
this is the case, some controllers have separate sets of contacts
that may be utilized in replacement of the damaged contacts.
Some rewiring and/or reprogramming will be needed. Contact
Fulton service department if necessary.
3. Temperature sensor failure
a. Different temperature controllers use different types of
temperature sensors. These may be Type J thermocouples,
mercury bulbs, RTDs or another type of sensor. It is possible for
these sensors to malfunction. To verify proper sensor operation,
use an alternate source of temperature detection such as an
infra-red temperature sensor to sense temperature at the same
point.
4. Control relay may have failed
a. Many temperature controllers energize a relay with a call for heat
that in turn closes a normally open set of contacts to energize
the burner circuit.
b. If your temperature controller is sending an output signal to the
control relay but the burner does is not initiated, check resistance
across coil of the relay. An open reading indicates that the relay