Closed loop ground source systems, Multiple units on one flow center, Figure 8: primary/secondary hook-up – Envision Peripherals R-410A User Manual

Page 9

ENVISION RESIDENTIAL INSTALLATION MANUAL

Figure 7: Closed Loop Ground Source Application

Closed Loop Ground Source Systems

Note: For closed loop systems with antifreeze protection, set SW2-2 to the “loop” position (see table on page 28).

Once piping is completed between the unit, pumps and the ground loop (see figure below), final purging and charging

of the loop is required. A flush cart (or a 1.5 HP pump minimum) 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. Flush the sys-

tem adequately to remove as much air as possible then pressurize the loop to a static pressure of 40-50 PSI (summer) or

50-75 PSI (winter). This is normally adequate for good system operation. Loop static pressure will fluctuate with the

seasons. Pressures will be higher in the winter months than during the cooling season. This fluctuation is normal and should

be considered when initially charging the system.

After pressurization, be sure to open the plug 1 turn in the end of the loop pump motor(s) (if applicable) to allow trapped

air to be discharged and to ensure that the motor housing has been flooded. Ensure that the loop pumps provide adequate

flow through the unit(s) by checking the pressure drop across the heat exchanger and comparing it to the unit capacity data

in the specification catalog. 2.5 to 3 GPM of flow per ton of cooling capacity is recommended in earth loop applications.

Multiple Units on

One Flow Center

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 8). The

loop pump(s) may be powered from either

unit, whichever is more convenient. If either

unit calls, the loop pump(s) will automati-

cally start. The use of two units on one flow

center is generally limited to a total of 20

GPM capacity.

Envision to

Electromechanical Units

Shut

Down

C C

SL1

Out

Envision Unit #1

To Electromechanical Unit

Shut

Down

C C

Shut

Down

C C

SL1

Out

SL1

Out

Single Speed
Envision Unit #1

With pump
wired to Unit 1

With pump
wired to
Unit 2

Envision to Envision

Microprocessor Units

Envision Unit #2
Single Speed

With pump
wired to Unit 1

With pump
wired to
Unit 2

Shut

Down

C C

Shut

Down

C C

SL1

Out

SL1

Out

Dual Capacity
Envision Unit #1

Envision Unit #2
Dual Capacity

Envision to Envision

Microprocessor Units

Figure 8: Primary/Secondary Hook-up

Flexible Duct
Collar

Vibration Absorbing Pad

P/T Plugs

Drain

Desuperheater
Connections

Auxiliary
Heater
Knockout

Low

Voltage to

Thermostat

Unit Supply

Auxiliary Heat
Supply

Insulated piping
or hose kit

Disconnects

(If Applicable)

Unit Power

P/T

LOOP

GeoL

ink

Flow

Cente

GeoLink

Polyethylene w/

Armaflex

Insulation

Note: Additional information can be found

in Flow Center installation manual (IM1961)

and Flush Cart manual (WFS302).