LAARS Mighty Therm LO-NOx PH (Sizes 250/400) - Install and Operating Manual - Manual (Page 26)

LAARS Heating Systems
Page 26
5.1.2 Checking the Manifold
Regulated Gas Pressure
1. Attach a manometer (or a dry gas pressure gauge)
to boiler jacket (see Figure 37).
2. Open both columns on the manometer.
3. Use shutoff valve, on outside of boiler jacket, to
shut off all gas supply to the boiler.
4. Remove the 1/8 inch NPT test plug on the outlet
side of the gas valve, and replace it with the 1/8
inch NPT fitting from the manometer kit.
5. Attach one end of the manometer hose to the
fitting on the gas valve and the other end to the
manometer.
6. Turn on gas supply to the boiler, and follow the
lighting instructions in Figures 28 or 29 to turn
on the boiler.
7. With the main burner firing, the manometer
reading should be 4 inches (10cm) W.C. for
natural gas.
8. Turn the toggle switch to OFF.
9. Shut the system down following the shutdown
instructions in Figures 28 or 29.
11. Disconnect the manometer tubing from the gas
valve and replace the 1/8 inch NPT fitting with
the original plug.
5.2 Electrical Troubleshooting
This section describes procedures for checking
the electrical power and control components of the
boiler. Read all of these procedures before starting
repairs.
Problems with boilers not firing are usually
caused by something reducing water flow through the
boiler, causing the protective switches in the boiler
system to shut down the boiler.
The following tools are required for proper
service and problem diagnosis of the boiler and
heating system.
1.
Gas pressure test kit with range from 0 to 14
inches (0 to 35.6 cm) W.C.
2. Electric meter(s) with the following ranges:
a. 0 to 500 volts VAC
b. 0 to 2000 ohms (
:)
c. 0 to 20 microamps (
PA)
3. Tube cleaning kit with a reamer, stainless steel
brush, speed handle, and handle extensions.
4. A pressure gauge and a thermometer with proper
ranges for boiler operation.
5.2.1 Boiler Does Not Come On
Important: Disconnect power to the boiler before
removing or replacing any component or wire
connection.
WARNING
If power is not disconnected, jumpering gas valve or
accidental grounding of the wire harness, or
component terminals to the boiler frame or jacket
could cause the ignition control fuse to blow or may
cause the boiler to fire, resulting in injury or property
damage.
MISE EN GARDE
Si l’alimentation électrique n’est pas coupée, un
contact avec la soupape de gaz, la mise à la terre
accidentelle du faisceau de câbles ou des bornes
des composants au cadre ou à la paroi de la
chaudière peut faire sauter les fusibles ou
provoquer l’allumage de la chaudière, occasionnant
des blessures des dégâts matériels.
1. Make sure the boiler has been properly installed.
2. Make sure the pump is not airlocked, clogged or
otherwise inoperative.
3. Make sure the gas valve is on and there is gas
pressure in the line.
4. Check all electrical connections and wiring.
Finding a loose connection or a charred wire can
save a lot of time and money.
5. Check the fuse inside the twist-lock fuse holder.
If it is burned, replace it with a 2-amp fuse (Part
No. E0084400). If there is a short, the cause of
the short must be found and repaired. Do not
jumper or bypass the fuse.
6. Make sure the electrical circuit to the boiler is on.
7. Make sure the toggle switch on the right side of
the boiler is on.
8. Make sure the temperature control is set high
enough to call for heat.
9. Make sure the manual reset on the safety controls
(e.g., low water cutoff, hi-limit switch, etc.) has
not tripped. If it has, reset it.
If the pump is circulating water, and the rest of
these items check out all right, the trouble could be in
the boiler control system.
Caution
Label all wires prior to disconnection when servicing
controls. Wiring errors can cause improper and
dangerous operation. Verify proper operation after
servicing.
Attention
Au moment de l’entretien des commandes,
étiquetez tous les fils avant de les débrancher. Les
erreurs de câblage peuvent nuire au bon
fonctionnement et être dangereuses. S’assurer que
l’appareil fonctionne adéquatement une fois
l’entretien terminé.
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