York YAWS018 - 075 Installation Manual page 9

Field Connected Water Piping cont.
Earth Coupled Systems with Flow Center
Once piping is completed between the unit, flow center
and the earth loop, final purging and charging of the loop
is needed. A flush cart (at least a 1.5 HP or 1.12 kW pump)
is needed to achieve adequate flow velocity in the loop to
purge air and dirt particles from the loop itself. Antifreeze
solution is used in most areas to prevent freezing. Maintain
the pH in the 7.6-8.2 range for final charging.
Flush the system adequately to remove as much air as
possible. Then, pressurize the loop to a static pressure of
50-75 psi [345-517 kPa]. This is normally adequate for good
system operation. Ensure that the flow center provides
adequate flow through the unit by checking pressure drop
across the heat exchanger and by comparing it to the
figures shown in the Pressure Drop tables. Usually, 3 GPM/
ton [0.054 L/s/kW] L/s/kW or minimum 2.25 GPM/ton
[0.04 L/s/kW] of cooling capacity is needed in closed loop
earth-coupled applications
Multiple Units on One Flow Center
NOTE: This feature is only available in the Aurora Advanced
Control package (AXB board), NOT the Aurora Base
Control (ABC).
When two units are connected to one loop pumping system,
pump control is automatically achieved by connecting the
SL terminals on connector P2 in both units with 2-wire
thermostat wire. These terminals are polarity dependant (see
Figure 8b). The loop pump(s) may be powered from either
unit, whichever is more convenient. If either unit calls, the loop
pump(s) will automatically start. The use of two units on one
flow center is generally limited to a total of 20 gpm capacity.
NOTE: To achieve this same feature when heat pumps have
only the Aurora Base Control, follow Figure 8a. Installer will
be required to supply fuses, two relays, and wiring.
AFFINITY SINGLE STAGE HYDRONIC INSTALLATION MANUAL
Typical Closed Loop Earth Coupled Installation
Line Voltage
Disconnect
Load Liquid
Connections
Figure 8a: Primary/Secondary Wiring with Aurora Base
Control (no AXB Board)
Ext Pump
Circuit
1/2 hp Total
PB1 Breaker
208-230/60/1
1
5A
1 1
2
Pump Pump Hot Water
5A
2
G Circuit Limit Switch
Breaker
HWG
Pump
Blue
Optional Internal
HWG Pump
Field Supplied
Relay for Heat
Pump 2
Figure 8b: Primary/Secondary Hook-up
5 Series to 5 Series to
5 Series Units Envision Units
5 Series Unit #1 5 Series Unit #1
with AXB Board with AXB Board
SLI SLO VS SLI
IN C OUT C IN C
With pump
With pump
wired to Unit 1
wired to
Unit 1
With pump
wired to
Unit 2
Shut
Down
IN C OUT C
Envision Unit #2
SLI SLO VS
5 Series Unit #2
with AXB Board
9
Earth Coupled Loop
Piping with Insulation
Unit Connector Kits
with Insulation
P/T Plugs
Vibration Absorbing
Mesh or Air Pad
Compressor
Blue
S C
R
Cap
Red
Black
Tan(6)
Field Supplied
Fuses 5A
130°F
Purple
T2 T1
CC
L2
L1
Cabinet
HW Switch
3
2
1
Field Supplied
Relay for Heat
Pump 1
Heat Pump 1
Contactor Coil
Heat Pump 2
Contactor Coil
5 Series to
Electromechanical Units
5 Series Unit #1
with AXB Board
SLO VS SLI SLO
OUT C IN C OUT C
With pump
wired to
Unit 2
SL1 SL1
C C
In Out
C S
T o Electromechanical Unit
VS