Install Instructions

6
E. Install Drain Valve in Tapping 'F'. See Figure 4.
Figure 5: Assembly Diagram for McDonnell & Miller 67 Low Water Cutoff
Figure 4: Purpose of Tappings
Table 3: Purpose of Tappings
F. Connect system supply and return piping to boiler.
See Figure 6. Also consult Residential Hydronic
Heating Installation and Design I=B=R Guide.
Maintain minimum ½ inch clearance from hot water
piping to combustible materials.
WARNING
Safety valve discharge piping must be piped near
oor to eliminate potential of severe burns. Do
not pipe in any area where freezing could occur.
Do not install any shut-off valves.
Tapping Size Purpose
A 2"
30 - 70: Plugged, Optional Second Supply
80: Second Supply
B ¾" Pressure Gauge (bushed to ¼)
C ½" Gauge Glass / Float LWCO
D 2" Return (Standard)
E ¾" Safety Valve
F 2" Drain Valve Return (Alternate)
G 2" Supply
H ¾" Limit
K ¾"
Probe Low Water Cutoff
(Plugged with McDonnell & Miller 67 LWCO)
III. Steam Piping and Trim (continued)