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5.1.2.4 Pipe Connection
The refrigerant pipes and indoor units are connected by using the flare opening. Therefore, the
quality of flaring connection must be ensured. The flaring depth of the bell mouth cannot be smaller than
the caliber. The flaring direction must face towards the direction of medium flow. Use two torque
wrenches to fasten the connection.
5.1.3 Air-tightness Test
Precautions:
(1) The measuring range of the test pressure gauge must be above 4.5 MPa for R410A system and
above 3.5 MPa for R134a system.
(2) Record the value displayed on the pressure gauge, ambient temperature, and test time.
(3) Pressure correction: The pressure changes by 0.01 MPa when the temperature changes by 1°C.
(4) The pressure meets the requirement if it does not change.
(5) If the pressure must be kept for a long time, decrease the pressure to 0.5 MPa or lower. High
pressure for a long time may cause leakage at the welding point or safety hazard.
(6) Before completing the air-tightness test to the refrigerant pipe, do not conduct thermal insulation
or wrapping at the points where the refrigerant pipe is connected to the outdoor unit of water heater
and water tank.
5.1.3.1 Importance of the Air-tightness Test
Air-tightness of the water heater system mainly refers to the tightness of the refrigerant pipes, which
ensures secure and reliable running of the water heater.
Refrigerant leakage may affect functions of the water heater or even damage the compressor and
make the system to break down. Therefore, an air-tightness test must be performed.
5.1.3.2 Procedure for Performing the Air-tightness Test
Cut-off valves of the gas and liquid pipes of outdoor unit of the water heater are turned off at
delivery.
Before test, apply a small amount of required lubricant on the block nut and pipe terminals and use
two wrenches to fix the block nut.
The outdoor unit pipes cannot be connected when the air-tightness test is being performed.
Use dry nitrogen as media for the air-tightness test. Increase the pressure slowly by following the
steps below:
Step 1: Increase the pressure to 0.5 MPa. Stop for 5 minutes and then perform air-tightness check.
Major leakage may be detected.
Step 2: Increase the pressure to 1.5 MPa. Stop for 5 minutes and then perform air-tightness check.
Minor leakage may be detected.
Step 3: Increase the pressure to the test pressure (4.15 MPa for R410A system and 3.15 MPa for
R134a system). Keep the test pressure for 1 hour and check whether it decreases. If the pressure does
not decrease, it meets the requirement.
AIR SOURCE HEAT PUMP WATER HEATER SERVICE MANUAL
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