Nimbus Plus S NET R32 Installation Manual UK

Hydraulic and

Hydraulic and refrigerant connections 4.2.1 Pressurised resistance test with nitrogen a – Connect the nitrogen cylinder through the pressure reducer and the flexible hose to the service socket ("Fig. 50"). – Fill the circuit between the pipes and the indoor unit with nitrogen. – The system must be pressurised gradually. If no leaks are found, continue increasing the pressure up to 1.1 times the maximum pressure specified on the rating plate and keep the system pressurised for 15 minutes. Make sure that the collars are not damaged. In case of damages, replace the damaged parts and restore the circuit to perform the test again. – If no leaks or damages are found, perform the tightness pressure test with nitrogen. 4.2.2 Pressurised tightness test with nitrogen – With the circuit already pressurised, reduce the pressure down to the maximum pressure specified on the rating plate and close the cylinder. – Note down the reading on the pressure gauge and the room temperature. – Leave the system pressurised for 3 hours. – If after 3 hours the value read by the pressure gauge has not changed by more than 0.01 MPa (0.1 bar) for each 1°C change in the outdoor air temperature with respect to the previously measured value, the system is sealed. Expel the nitrogen very carefully, due to the high pressures involved. Proceed with a vacuum test (see paragraph “Vacuum operation”). – If after 3 hours the value read by the pressure gauge has changed by more than 0.01 MPa (0.1) bar for each 1°C change, the system is not sealed. Pressurise the gas again, identify the leak and repair it. Repeat the tightness test. 4.3 Vacuum operation Air and moisture in the refrigeration circuit cause undesired effects on the unit’s operation. The vacuum operation is carried out in pipes connecting the outdoor and indoor units for eliminating moisture and non-condensable gases from the system. If the outdoor air temperature is below 10°C, the triple-evacuation procedure must be carried out (refer to the paragraph " Triple evacuation"). For the opening and closing phases of the Flare valves described in the next paragraphs, refer to the figure "Fig. 51". A B Opening Closing A – Connect the pipes as shown in the figure "Fig. 52". 1 1 Gas-side flare valve 2 Vacuum pump 3 Pressure gauge unit BP Low pressure warning AP High pressure 1 2 BP B B 3 C A Fig. 51 AP Fig. 52 – Check that all the cocks of the pressure gauge unit are closed. – Open connections between (B) and (C). – Switch on the pump. – Reach a vacuum level of 200 microns (0,27 mbar) and continue for 15 minutes. 30 / EN

Hydraulic and refrigerant connections a – Close all the cocks of the pressure gauge unit. – Switch off the pump. – Make sure that the pressure does not exceed 210 microns (0.28 mbar) after 10 min. If the pressure exceeds this value, check the connections and repeat the discharge procedure (vacuum level: 200 microns (0.27 mbar)). – If the system’s length is below 20 m, no additional charge is required. Proceed as explained below. – Slightly open the shut-off valve (1) for a few seconds and then close it ("Fig. 52"). – Disconnect the vacuum pipe from the appliance. – Fully open both the shut-off valves. – Put the caps back onto the valves and tighten them properly. – Use a leak detector suitable to the refrigerant to check that there are no leaks from the shut-off valves and from the caps. Failing to put the caps back on and tightening them can cause refrigerant leaks. Do not damage the internal parts of the valve caps as they function as a seal that prevents refrigerant leaks. 4.4 Triple evacuation The triple-evacuation procedure must be carried out alternatively to the vacuum procedure when the outdoor air temperature is below 10°C. – Close the cocks of the pressure gauge unit. – Connect the piping for the vacuum as shown in "Fig. 53" and the pipe for the nitrogen cylinder. – Switch on the vacuum pump, open the connection between (C) and (B), open the valve (BP) of the pressure gauge unit to start the evacuation. – Reach a vacuum level of 1000 microns (1,33 mbar) and continue for 5 minutes. – Shut off the pump and switch it off. – Open (AP) to fill the circuit with nitrogen and reach a pressure of 0.1 MPa (1 bar). – Close the cylinder and repeat the vacuum operation up to a level of 500 microns (0,67 mbar) for 10 minutes. – Evacuate the system for a third time, up to a vacuum level of 200 microns (0,27 mbar) for 15 minutes. 2 1 2 3 4 1 Liquid-side flare valve 2 Gas-side flare valve 3 Vacuum pump 4 Nitrogen cylinder BP Low pressure warning AP High pressure – Switch off the pump. BP B C A AP Fig. 53 – Make sure that the pressure does not exceed 210 microns (0,28 mbar) after 10 minutes. If it exceeds this value, check the connections and repeat the entire procedure from the beginning. – If the system’s length is below 20 m, no additional charge is required. Proceed as explained below. – Slightly open the shut-off valve (2) for a few seconds then re-close it (“Fig. 53”). – Disconnect the vacuum pipe from the appliance. – Fully open both the shut-off valves. – Put the caps back onto the valves and tighten them properly. – Use a leak detector suitable to the refrigerant to check that there are no leaks from the shut-off valves and from the caps. 31 / EN