V Wiring – continued
Sequence of operation 1. Operating control begins startup sequence.
a.Limit control contacts are closed.
2.Pilot proving module energized.
a.Pilot solenoid opens.
b.Pilot ignition spark begins.
c.Pilot ignites.
d.Pilot proves.
On failure to sense pilot flame, the
3.Main flame proving module energized from pilot proving module.
a.Secondary gas valve opens.
b.Main gas valve opens to low fire position.
c.Main burners ignite at low fire.
d.Main flame sensor proves low fire carryover.
e.Main gas valve opens to high fire position.
f.Main burners increase to high fire.
On failure to sense main flame, the main
4.For dual base assembly - operating control energizes controls for each base assembly at the same time. See steps 1 through 3 above.
5.Boiler shuts down when operating control satisfied.
If the boiler locks out, the alarm contacts on the terminal strip (terminals A1 and A2) close. These contacts are rated to 15 amps, 250 V. To reset the boiler, push the red lockout button.
Wiring procedure 1. Determine right or left electrical supply wiring.
2.Attach electrical junction box(es) to inside jacket end panel. Screws and nuts are provided. For dual base boilers, use offset nipples (provided) to connect junction boxes together (as at right), then hang junction boxes by screwing top box to boiler jacket. See Figure 4.
3.Attach control transformer(s) to junction box(es).
4.Drill 1/8” hole in interior jacket panel midway between ignition control panel and left jacket panel. Mount wire support clip using sheet metal screw (furnished).
5.Complete wiring per diagrams, Figure 3 (pages 6 and 7) and Figure 5 (page 9). Terminate at secondary gas valve in valve junction box with wirenuts and strain relief provided.
“Hot” side of line voltage to boiler must be wired directly to limit circuit, then fed to transformer primary(ies).
Dual Base: “R” terminal of secondaries are to supply power to bases independently of each other. Do not wire “R” terminals together.
6.Install pilot proving and main flame proving ground connections as shown in Figures 1 and 2 and wiring diagram. Route wires through wire support clip.
Figure 4
Junction box assembly dual base boilers
8 | Part Number |
