Envision Peripherals R-410A Closed Loop Ground Source Systems, Multiple Units on One Flow Center

ENVISION RESIDENTIAL INSTALLATION MANUAL

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 system 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.

Figure 7: Closed Loop Ground Source Application

Auxiliary Heat	GeoLink®
Supply	Polyethylene w/
Unit Supply	Armaflex®
	Insulation
	Flexible Duct
	Collar
	Auxiliary
	Heater
	Knockout
	Unit Power
	Desuperheater
	Connections

Disconnects

(If Applicable)

Drain

Low	P/T
Voltage to	P/T Plugs
Thermostat
Vibration	Absorbing Pad

TO

LOOP

	oLink		®
Ge
Flow
Cent		er

Insulated piping or hose kit

Note: Additional information can be found in Flow Center installation manual (IM1961) and Flush Cart manual (WFS302).

Multiple Units on

One Flow Center

When two units are connected to one loop pumping system, pump control is

Figure 8: Primary/Secondary Hook-up

Envision to Envision	Envision to Envision	Envision to
Microprocessor Units	Microprocessor Units	Electromechanical Units

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.

Dual Capacity Envision Unit #1

Shut	C	C	SL1	SL1
Down			In	Out
With pump
wired to Unit 1
With pump
wired to
Unit 2
Shut	C	C	SL1	SL1
Down			In	Out

Envision Unit #2 Dual Capacity

Single Speed

Envision Unit #1

Shut	C	C	SL1	SL1
Down			In	Out

With pump wired to Unit 1

With pump wired to Unit 2

Shut	C	C	SL1	SL1
Down			In	Out

Envision Unit #2

Single Speed

Envision Unit #1

Shut	C	C	SL1	SL1
Down			In	Out

C S

To Electromechanical Unit

9