Lennox VPB Series, Installation & Operation Instructions

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2

3

4

5

6

6

•  The seal on the unit refrigerant piping connec-

tions should remain in place until the last pos-

sible moment. This will prevent dust or water 

from getting into the refrigerant piping before it 

is connected.

• 

Flow  the  pipework  with  dry  (oxygen-free)  nitro

-

gen (2.9 psig or 3 CFH) during brazing to avoid 

oxidation which may block the refrigerant piping.

• 

Do not use flux when brazing copper-to-copper 

piping. Use phosphor copper brazing filler alloy 

(BCuP) which does not require flux. Flux has a 

harmful effect on refrigerant pipe.

• 

Use a wet cloth to insulate the shut off valve dur

-

ing brazing.

•  Use dedicated gauges and hoses with R-410A 

equipment. 

Pressure Test

• 

Follow the pressure test specifications in Table 2 

for proper pressure testing procedures.

•  Ensure the unit service valves are fully closed 

and haven’t become loose during transportation.

• 

Use oxygen-free nitrogen to pressure test to 650 

psig and hold for 1 hour.

Evacuate System

• 

Follow  the  Lennox  pressure  test  specifications 

in table 1 and the triple evacuation process de-

scribed on this page to pressure test and evacu-

ate the system. 

•  Use a vacuum pump capable of evacuating to 

lower than 500 Microns (0.5 Torr).

• 

Do  not  open  any  of  the  outdoor  unit  shut-off 

valves (possible max 5 valves). The outdoor unit 

does not need to be evacuated.

• 

Evacuate the system to 500 Microns (0.5 Torr), or 

below, for 4 hours. 

1 - Refrigerant pipe

2 - Part to be brazed

3 - Reducer

4 - Isolation valve

5 - Pressure-regulating valve

6 - Oxygen-free nitrogen

Figure 21. Brazing Best Practices

Table 2. Pressure Test Specifications

1 3 bar

44 psig

minimum of 10 minutes

2 15 bar 220 psig minimum of 10 minutes
3 32 bar 470 psig minimum of 10 minutes
4 45 bar 500 psig 1 hour. Stress test to 

prove the integrity of the 

complete installation.

5 32 bar 470 psig 24 hours. Lower system 

pressure test, after 

confirmation No. 4 was 

successfully completed.

Triple Evacuation Procedure

A Micron or Torr gauge must be used for this 

procedure.
1. 

Discharge the oxygen-free nitrogen and evacuate 

the system to a reading of 8000 Microns (8 Torr) 

using all service valves.

2.  Break the vacuum by allowing nitrogen into the 

three inter-connecting pipework port connections 

(low pressure gas pipe, high pressure gas pipe 

and liquid line pipe) until a positive pressure is 

achieved. 

3.  Evacuate the system to a reading of 5000 

Microns (5 Torr).

4.  Break the vacuum by allowing nitrogen into the 

three inter-connecting pipework port connections 

(low pressure gas pipe, high pressure gas pipe 

and liquid line pipe) until a positive pressure is 

achieved 

5.  Evacuate the system to a minimum reading of 

500 Microns (0.5 Torr).

6. 

For a moisture free system, ensure the vacuum 

is held without movement for a minimum of 4 

hours.

7. 

If  pressure  loss  is  detected,  carry  out  steps  2 

through 6 until no pressure loss is observed.

IMPORTANT!

Use only oxygen-free nitrogen (OFN).