Carrier 42 SERIES - Manual (Page 19)

Three-Way Motorized Control Valve
On the 3-way motorized valve flow is normally closed
to coil and open to system return. Motor closes bypass
flow to system return while opening flow through coil.
Water bypasses coil and flows directly to system return
when unit is OFF.
The aquastat (A) clips on supply line upstream from
3-way valve (as shown above). It senses system water
temperature to prevent cooling operation with hot wa-
ter in system piping or heating operation with chilled wa-
ter in system piping. Aquastat(s) required for 2-pipe cooling
and heating with automatic changeover control and/or
auxiliary electric heat.
A bypass balancing valve may be specified in the by-
pass line to permit equal flow balancing.
Supply and return connections at coil will be swage fit
for field braze (standard) or unions (option).
Check job specifications for system pressure, pres-
sure drop limitations and flow rate prior to selecting valve
package components or valve package size (
1 ⁄
2
Љ , 3 ⁄
4
Љ ,
etc.).
2-PIPE SYSTEM (One Valve Package) or 4-PIPE SYS-
TEM (Two Valve Packages) Application:
• 2 Pipe - Hydronic Heating Only
• 2 Pipe - Hydronic Cooling Only
• 2 Pipe - Hydronic Cooling with Total Electric Heat
• 2 Pipe - Hydronic Cooling and Heating
• 2 Pipe - Hydronic Cooling and Heating with Auxiliary
Electric Heat
• 4 Pipe - Hydronic Cooling and Heating
No Motorized Control Valve
When isolation valves only are specified, they will be
brazed to the coil stub-outs.
Check job specifications for system pressure, pres-
sure drop limitations and flow rate prior to selecting spe-
cific components or valve package size (
1 ⁄
2
Љ , 3 ⁄
4
Љ , etc.).
2-PIPE SYSTEM ONLY (One Valve Package)
Application:
• 2 Pipe - Hydronic Heating Only
• 2 Pipe - Hydronic Cooling Only
NOTES:
1. Continuous water flow, chilled water or hot water.
2. Not recommended for high humidity applications.
3. Not recommended with unit-mounted thermostat on
vertical units (except package R).
4. The addition of any other component(s) will require
swage fitting for field braze or optional union conec-
tion.
19