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10
ENVISION RESIDENTIAL INSTALLATION MANUAL
Open Loop Ground Water Systems
Typical open loop piping is shown below. Always maintain water pressure in the heat exchanger by placing water control
valves at the outlet of the unit to prevent mineral precipitation. Use a closed, bladder-type expansion tank to minimize
mineral formation due to air exposure. Insure proper water fl ow through the unit by checking pressure drop across the heat
exchanger and comparing it to the fi gures in unit capacity data tables in the specifi cation catalog. 1.5-2 GPM of fl ow per ton
of cooling capacity is recommended in open loop applications. Due to only minor differences in fl ow rate from low to high,
only one solenoid valve should be used. The valve should be sized for full fl ow.
Discharge water from the unit is not contaminated in any manner and can be disposed of in various ways, depending
on local codes, i.e. recharge well, storm sewer, drain fi eld, adjacent stream or pond, etc. Most local codes forbid the use of
sanitary sewer for disposal. Consult your local building and zoning departments to assure compliance in your area.
Note: For open loop/groundwater systems or systems that do not contain an antifreeze solution, set SW2-Switch #2 to the
“WELL” position. (Refer to the table on page 28.) Slow opening/closing solenoid valves (type VM) are recommended to eliminate
water hammer.
Acc Com
Acc NC
Acc NO
1
2
3
C
R
P1
P3
SV
Solenoid
Valve
CC-GND
CC
CCHI
Comfort
Alert
Y1
Y2
Lo
g
ic Board
Violet
(
3
)
Blk
(
1
)
Wht(4)
VM valve
Violet
(
2
)
CC
Figure 9b: Open Loop Solenoid Valve Connection Option
Typical slow operating external 24V water solenoid valve
(type VM) wiring.
Figure 9a: Open Loop Solenoid Valve Connection Option
Typical quick operating external 24V water solenoid valve
(type PPV100 or BPV100) wiring.
Flexible
Duct Collar
Vibration
Absorbing Pad
P/T Plugs
Drain
Desuperheater
Connections
Auxiliary
Heater
Knockout
Low Voltage
to Thermostat
and Valve
Unit Supply
Aux. Heat Supply
Water Out
Water In
Shut Off Valves
Boiler Drains
For HX Flushing
Disconnects
(IfApplicable)
Rubber Bladder
Expansion Tank
Solenoid
Valve
Shut Off Valves
(to isolate solenoid
valve while acid flushing)
Strainer
Flow Control
Valve
(on outlet of
Solenoid Valve)
Compressor
Line Voltage
Figure 10: Open System - Groundwater Application
Note:
SW2-3 should be in the Comp “ON” position.