Monessen Hearth VFCS20DNV - Manual (Page 16)

16 58D6002
CAUTION
Label all wires prior to
disconnection when
servicing controls.
Wiring errors can cause
improper and dangerous
operation. Verify proper
operation after servicing.
ELECTRICAL WIRING (MILLIVOLT)
The millivolt valve is a self-powered combination gas control THAT DOES NOT REQUIRE 110 VAC TO OPER-
ATE.
On/Off
Switch
On/Off
Switch
ODS
Pilot
Wall
Switch
Optional Wall
Switch or
Remote
ODS Pilot
Millivolt
Valve
Spade Terminal
3
1
2
CONNECTION
1 = TP
2 = TP, TH
3 = TH
Figure 13 - Wiring Diagram
CONNECTING OPTIONAL WALL SWITCH
1. Use 18 awg, two-wire cable, 15 feet maximum length.
2. At one end of the cable, connect both wires to the wall switch. At the other end, connect one wire to TP/TH
and one wire to TH, or connect the wall switch to the two male (0.25") terminals on the left side of the unit.
The color of the wires does not matter.
A. COMPLETE MILLIVOLT SYSTEM CHECk
("A" Reading - On/Off switch contacts CLOSED - Control knob “ON” - Main Burners should turn ON)
a. If the reading is more than 175 millivolts and the automatic valve still does not come on - replace the
valve.
b. If the closed circuit reading ("A" reading) is less than 175 millivolts, determine cause for low reading - pro-
ceed as follows:
B. THERMOPILE OUTPUT READING CHECk
(“B” Reading - On/Off switch contacts OPEN - Main burner OFF)
Check gas pressure to the unit. If gas pressure is within minimum and maximum on data plate, then replace
pilot. If the minimum millivolt reading is not obtainable, replace pilot.
CHECkING SYSTEM OPERATION
The millivolt system and individual
components may be checked with a mil-
livolt meter having a 0-1000mv range.
Conduct each check shown in chart by
connecting meter test leads to terminals
as indicated.
Switch
CHECk
TEST
TO TEST CONNECT METER
LEADS TO TERMINALS
METER READING
SHOULD BE
A COMPLETE 2 & 3 SYSTEM MINIMUM 175mv
B THERMOPILE
OUTPUT
1 & 2 SYSTEM 500mv OR MORE