Product Overview

20
Feeder Wiring for Boilers Equipped with McDonnell & Miller #67 Low Water Cut-offs
Figures 14a and 14b show feeder wiring for McDonnell & Miller #101A, McDonnell & Miller WF2-U-24 and Hydrolevel
VXT-24 feeders on boilers equipped with #67 low water cutoffs. The following points apply to all feeder wiring to #67 low
water cut-offs:
• Use a separate transformer to power the feeder. Do not use the transformer on the boiler.
• It is not necessary to touch any of the 24 volt factory boiler wiring when connecting a feeder to a #67 equipped
boiler.
• Do NOT install a jumper between terminals 2 and 3 on the #67 low water cutoff.
Indirect Water Heater Wiring
Figure15showseldwiringforanindirectwaterheater.AHoneywellR845AorequivalentDPSTrelayandtransformer
is required. The high limit described in Part IX must also be supplied by the installer. A call for heat from the indirect water
heater thermostat will energize the relay making both sets of contacts. One set of these contacts then energizes the circulator.
Theothersetofcontactswillmakethe“T”and“T”contactsontheburnerprimarycontrol,ringtheburner.Iftheboiler
water temperature exceeds the high limit setting of 180°F, the high limit will open the “T”-“T” circuit and the burner will
shut down.
Ifthereisacallforspaceheat,theheatingthermostatwillmakethe“T”-“T”circuitandtheboilerwillrewithoutregard
to the status of the indirect water heater. The low water cut-off and pressure limit control will interrupt 120 volt power to the
burner in the event of a low water or excessive pressure condition.
FIGURE 14a: WIRING MCDONNELL & MILLER 101A OR TWO-WIRE HYDROLEVEL
VXT-24 FEEDER TO BOILER EQUIPPED WITH #67 LWCO
X. Electrical (continued)
CAUTION
DO NOT INSTALL
JUMPER BETWEEN 2 & 3
ON #67 LWCO