McQuay MHC Series, Installation & Maintenance Data, Page: 10 / 36

Page 10 of 36 / IM 985-1
Motorized Isolation Valve
The­2-way­motorized­valve­kit­is­available­as­a­factory-
installed and wired option or may be ordered as a field-
installed­accessory .
Wired­as­shown­in­Figure­8,­the­motorized­valve­will­open­
on­a­call­for­compressor­operation .­Valves­for­unit­sizes­
007 to 018 are 1/2".
Figure­8­illustrates­the­wiring­for­a­Normally­Closed­(NC),­
power­open­motorized­valve .
Figure 8. Normally Closed, Power Open Motorized Valve
Wiring
Note: Connectors on valve must be cut off and
stripped back and the wires twisted to make
connections to the H8 (IV/PR) terminals on the
MicroTech III controller.
Note: All plumbing connections are made the same,
whether or not the unit has valve packages. Plumbing
connections must conform with local piping and
building codes. The ability to remove the unit in order
to perform repairs is imperative.
Condensate Hose Connection
Each unit is supplied with a 3/4" (19mm) I.D. clear vinyl
condensate­hose­internally­trapped­within­the­chassis .­The­
hose extends 3½" (89mm) out of the chassis within the
piping compartment to reach the floor or the back wall.
Field condensate piping must enter within the confines of
the cabinet (back wall or floor) similar to the supply and
return­ piping .­ Slide­ the­ vinyl­ hose­ over­ the­ condensate­
pipe­and­clamp­it .
10% 20% 30% 40% 50%
Cooling Capacity
0.9980 0.9720 – – –
Heating Capacity
0.9950 0.9700 – – –
Pressure Drop
1.0230 1.0570 – – –
10% 20% 30% 40% 50%
Cooling Capacity
0.9900 0.9800 0.9700 0.9600 0.9500
Heating Capacity
0.9870 0.9750 0.9620 0.9420 0.9300
Pressure Drop
1.0700 1.1500 1.2500 1.3700 1.4200
10% 20% 30% 40% 50%
Cooling Capacity
0.9950 0.9920 0.9870 0.9830 0.9790
Heating Capacity
0.9910 0.9820 0.9770 0.9690 0.9610
Pressure Drop
1.0700 1.1300 1.1800 1.2600 1.2800
Table 2. Antifreeze Correction Factors
Ethylene Glycol
Propylene Glycol
Methanol
Ethanol
10% 20% 30% 40% 50%
Cooling Capacity
0.9910 0.9510 – – –
Heating Capacity
0.9950 0.9600 – – –
Pressure Drop
1.0350 0.9600 – – –
Actuator &
Valve Assembly
Anti-short Bushing
Connector
Conduit
Pin(s), female
connect to terminal H8
Connector
Anti-short
Bushing