LAARS Mighty Max HH (Sizes 320M - 400M) - Installation, Operation and Maintenance Instructions - Manual (Page 26)

Page 26
LAARS Heating Systems
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 boiler 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 operates 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
boiler is turned off then back on or 120 Vac power to
the boiler is interrupted.
5.2 Venturi and Gas Pressure Regulator
System
5.2.1 Field Checkout
See Section 3.2 “Venturi and Gas Pressure
Regulator System” for proper setup procedure.
5.3 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.
5.3.1 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.
CAUTION
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.
ATTENTION
Débranchez la chaudière avant d’enlever ou de
remplacer tout élément ou branchement de fil. Si la
chaudière est branchée, « connecter » la valve de
gaz ou mettre accidentellement à la terre le
faisceau de fils ou des terminaux au corps ou à la
gaine de la chaudière peut faire sauter le plomb
(ou disjoncteur) de la commande d’allumage.
5.3.2 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.
OUT OF
PRODUCTION