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LAARS HEATING SYSTEMS
Figure 21. Lower Front Panel Removal.
5B. Venturi and Gas Pressure Regulator
System
5B-1. 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
boiler. Refer to the wiring diagram for correct
connection locations.
5C-1. General Troubleshooting
This section describes guidelines for checking
the electrical components of the boiler. Experience
has shown that most complaints about boilers failing
to fire have nothing to do with the boiler itself.
Usually, one of the protective switches in the boiler
system has shut down operation.
Any of the following can prevent proper
operation. Check these items first:
1.
Be sure the boiler 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.
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 no. 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 boiler
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 boiler
frame or jacket could cause the ignition control fuse to
blow.
5C-2. Electrical Troubleshooting
Troubleshooting procedures should only be
performed by professional service technicians
qualified in heater maintenance.
Some electrical components are wired in
parallel, so it is necessary to troubleshoot in the order
that they appear on the wiring diagram or the
troubleshooting flow chart (see Figure 20).
NOTE: When testing the safeties between
“MV1” of the ignition control and the gas valve(s)
there is only a seven (7) second trial for ignition
period during which there is power to “MV1”.
The following steps should be used when
troubleshooting the boiler:
1.
Remove the lower front panel (see Figure 21).
2.
Turn the manual gas valve on the heater off.
3.
If the heater has locked out turn the toggle
switch off for 5 seconds then back on to reset the
heater.
4.
Use the troubleshooting flow chart (see Figure
20) to determine what components and wiring
should be tested first.
5.
Test each component by checking for 24 Vac or
120 Vac entering and exiting the device. If there
is voltage entering the safety device, but none
leaving then there is an open circuit and it must
be determined why it is open. When testing
components between “MV1” of the ignition
control and the gas valve install a meter and let
the heater cycle through one complete sequence
of operation. During the sequence of operation
these safeties will only be energized for the
seven second trial for ignition.
6.
Turn the manual gas valve on the boiler on and
fire the boiler.
