77
Call 1-
800-347-9575
for Technical Support
9.3.5 Preheater and Nozzle PTC Testing Procedure
Tools Required:
1/4”, 5/16” wrenches, alligator clips or jumper wire, 120VAC capable Digital Multi-Meter DMM,
temperature probe, or the TPI combustion analyzer with a type K thermocouple attached.
Preheater/Nozzle PTC Function:
Heats the fuel to a temperature over 120°F for proper combustion. There are standby PTCs in
the Preheater and the Nozzle that are energized whenever there is power to the burner in
order to keep the fuel warm for immediate start up. When the burner is firing, there are extra
run PTCs in the Preheater that energize to heat the fuel as it flows to the nozzle.
Note:
During this test, if the preheater does not function as stated, call Technical Services for
assistance, or Customer Service to order a new preheater.
The preheaters are on at all times, making the nozzle block and external
preheater assembly very hot to the touch.
Make sure the Preheater has recently been maintained. Neglect will negatively
affect the results of testing
During a portion of this test, high voltage electrical components will be
energized. Only a certified electrician is to perform the following procedures, and with
extreme caution.
Procedure:
1. With the burner unplugged, verify the pins at the preheater plug and receptacle are
straight and secure.
2. Check the 8 Amp fuse (refer to figure below). If the fuse is blown, there is a high
probability that at least one of the run PTCs has shorted out.
3. Remove the thermostat connector / jumper from the side of the primary control and/or
any jumpers across the T-T terminals.
4. Disconnect the preheater plug. Allow the preheater to cool, and check the following with
the digital multimeter:
a. Verify that the circuit between the
two thermostat pins is open (if
preheater is cool) or closed (if
preheater is hot).
b. Verify that there is a resistance of
100-1000 ohms between the
standby power and neutral pins.
c. Verify that there is a resistance of
100-1000 ohms between the run power and neutral pins.
If any of these tests fail, the preheater will need to be replaced.
Wide Key at Top
Standby Heater - Neutral
Standby Heater
– 115V
Preheater Thermostat
Run Heaters
– 115V
Run Heaters - Neutral
(Center Pin Not Used on 200B.
Used for Solenoid Valve on
375B and 500B.)
Preheater Plug
T-Stat
Jumper
Model
200B
375B
500B
Pump Shaft Speed
Gear Box Model
115V
241 - 300
483 - 600
161 - 200
115V
3GN6KA
3GN3KA
3GN9KA
8 Amp Run Fuse
Preheater Plug
