Laars Mighty Max VW Series, Инструкции по установке, эксплуатации и обслуживанию

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Page 24
LAARS HEATING SYSTEMS
developed. The factory recommends cleaning the filter
at least once every 30 days. In high contamination
areas, such as construction sites, factories, etc., the
filter may need to be cleaned daily. Failure to do so
could result in lower heat output and potential unsafe
operation.
SECTION 5
Troubleshooting
5A. Sequence of Operation
To troubleshoot the heater properly you must
first understand the sequence of operation of the
heater:
1. Upon a call for heat a 24 Vac signal is sent
through fusible links and high limit(s) to the
ignition control “TH” terminal.
2. The “IND” terminal of the ignition control is
energized for a 15 second pre-ignition purge
period during which the combustion blower
purges the combustion chamber.
3. After the purge period there is a 20 to 35 second
igniter heat up period. The glow of the igniter
can be seen through the heater sight glass.
4. Then there is a seven second trial for ignition.
During this time the gas valves are energized and
the main burner ignites. The gas valves will
remain energized throughout the call for heat as
long as the ignition control igniter senses a
stable flame.
5. After the call for heat is satisfied the ignition
control closes the gas valves and operate the
blower for a thirty (30) second post purge cycle.
This clears the combustion chamber of
combustion products.
The ignition is attempted three times. If ignition
is not successful, the control shuts down and “locks
out”. It remains in the lockout condition until the
heater is turned off then back on or 120 Vac power to
the heater is interrupted.
5B. Venturi and Gas Pressure
Regulator System
Field Checkout
See Section 3B “Venturi and Gas Pressure
Regulator System” for proper setup procedure.
5C. Electrical Components
This section describes guidelines for checking
the operation of electrical components installed on the
heater. Refer to the wiring diagram for correct
connection locations.
5C-1. General Troubleshooting
This section describes guidelines for checking
the electrical components of the heater. Experience
has shown that most complaints about heaters failing
to fire have nothing to do with the heater itself.
Usually, one of the protective switches in the heater
system has shut down operation.
Any of the following can prevent proper
operation. Check these items first:
1. Be sure the heater has been properly installed
(see Section 2).
2. Make sure the pump is not airlocked, clogged or
otherwise inoperative.
3. Make sure the gas valve is on and there is
sufficient gas pressure in the line. All external
gas valves must be open.
Caution
The ignition control and igniter operate on 120V
power. Keep this in mind while servicing the heater,
and take care to avoid electrical shock.
4. Verify that the electrical circuit serving the
boiler is ON
5. Make sure the toggle switch on the right side of
the boiler is ON.
6. Check the fuse inside the black, twist-lock fuse
holder. If it is burned, replace it with a 2-amp
fuse (part number E0084400).
7. With the power off inspect all electrical
connections and wiring. Finding a loose
connection or charred wire can save a lot of time
and money.
8. Make sure the temperature controller is set high
enough to call for heat.
9. Make sure none of the manual reset controls, i.e.,
low water cutoff, high limit, etc., have tripped.
Reset any tripped switches
If the pump is circulating water and the
foregoing items check out okay, the trouble may be in
the boiler control system.
IMPORTANT: Disconnect power to the heater
before removing or replacing any component or wire
connection. If the power is not disconnected,
“jumping” the gas valve or accidentally grounding the
wire harness or component terminals to the heater
frame or jacket could cause the ignition control fuse to
blow.