Fulton Vertical Tubeless (FT-A) Thermal Fluid (hot oil) Heater - Manual (Page 68)

© The Fulton Companies 2013
MAINTENANCE
FTA-IOM-2013-0227
SECTION 4
4-8
!
WARNING
All information in this manual is for
reference and guidance purposes,
and does not substitute for required
professional training, conduct,
and strict adherence to applicable
jurisdictional/professional codes and
regulations.
4
CAUTION
All maintenance procedures should
be completed by trained personnel.
Appropriate training and instructions
are available from the Fulton Service
Department at (315) 298-5121 or your
local Fulton Thermal Representative.
for a tripped Low Inlet Pressure Switch.
HIGH OUTLET PRESSURE SWITCH
All A-Model heaters have a High Outlet Pressure Switch. This is a normally closed
switch that opens with excessive heater outlet pressure.
This switch is generally a mercury bulb type switch. Mercury will rest towards the
green cap in a “made” condition.
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 150 psi with 100 psi safety valve(s) on the heater outlet manifold.
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 in Table 10-B are true.
Refer to Table 10-B for a tripped High Outlet Pressure Switch, which will require
the manual reset button on the switch to be pushed.
FLOW SWITCHES
Units older than mid-1993 have Flow Switches on the inlet of each heater.
These are normally open switches that close, making a micro-switch, upon fl ow
establishment.
The purpose of the Flow Switch(es) is to protect the heater from too high of a
temperature and to protect the thermal fl uid from exceeding its maximum fi lm
temperature. Each fl ow switch is wired in series requiring fl ow through each pipe
. Refer to Table 10-C for fl ow switch troubleshooting.
DIFFERENTIAL PRESSURE SWITCH
Units newer than mid-1993 have a Diff erential Pressure Switch. This is a normally
open diaphragm switch that closes with a proper heater diff erential pressure
between the heater inlet and outlet.
The purpose of the Diff erential Pressure Switch is to protect the heater from
too high of a temperature and to protect the thermal fl uid from exceeding its
maximum fi lm temperature. Each heater model number has a specifi c minimum
diff erential pressure.
This pressure is the diff erence in pressure between the heater inlet pressure
gauge and the heater outlet pressure gauge. See Table 10-D for troubleshooting.
CALL FOR HEAT/BURNER INTERLOCK
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. Generally these controls work in combination with a control relay.
When the Temperature Controller calls for heat, a signal is sent to that closes a
normally open set of contacts in series with the burner circuit.
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 are
in Table 10-E. The burner interlock is the electrical circuit that enables the fl ame
programmer. Your thermal heater needs to have the items in the burner interlock
‘made’ before ignition can occur. Items in the burner interlock may include an air
switch, air fi lter switch, auxiliary blower motor starter contacts, high temperature
limit(s), high gas pressure switch, low gas pressure switch, and / or low oil