HVAC: Filling the system

Filling the refrigerant; Pumping down and disconnecting the hoses; Immediate leak tightness check.

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The installation has been tested and vacuumed.

Now we put the refrigerant back in the set. Here we have the following tools.

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A manifold gauge set
A scale
A recovery cylinder
An electronic leak detector or sniffer

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The assignment consists of three parts.

Filling the refrigerant;
Pumping down and disconnecting the hoses;
Immediate leak tightness check.

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Filling the refrigerant

During the vacuuming, the hose has already been taken after the recovery cylinder.

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So for the change we don't have to vacuum everything now. Freon flows directly from the cylinder into the installation.

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The weight of the recovery cylinder is 11.7 kilograms.

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That's 1.5 kilograms in the installation. So we have to fill up until the cylinder weighs 10.2 kilograms.

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We start with the cylinder. First we put the cylinder flange open.

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Then we first open the closure to the manometer set.

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And then the one after the installation. Now it starts to run with liquid.

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We wait until the cylinder weighs 10.2 kilograms.

Then we know for sure that there is 1.5 kilograms in the installation.

We see that the last bit from the bottle does not want to go in.

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So it keeps sticking to 10.3-4 kilograms. To ensure that the last bit from the bottle also comes into the installation, we heat the recovery cylinder.

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We can do that by putting it in a container with hot water. Or we use the heat gun.

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Pumping down and disconnecting the hoses

The hoses are full of refrigerant.

If we were to disconnect them now, it would still result in emissions.

Vacuuming with a vacuum pump isn’t an option either, because that would release the Freon into the open air.

To work completely emission-free, we use the system’s compressor to evacuate the hoses.

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We use the system’s compressor to suck the refrigerant out of the hoses.

If we leave both valves open, the refrigerant would just circulate in a loop and vacuuming would have no effect at all.

We have to close one of the closures, which is the red one.

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Now the installation is running and we start vacuuming the hose.

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We start with the red closure.

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Then we put the black one open.

It’s the hose to the recovery cylinder — we vacuum that at the same time.

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Then we carefully open the blue closure.

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We open a small part of it, until all the liquid in the manifold gauge set is evaporated.

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We open the blue closure carefully.

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The pressure on both gauges is now equal, and we can now fully open the blue gauge.

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To extract the last bit of refrigerant from the hoses, we switch off the system.

We briefly hold down the button.

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Now the solenoid valve will close, triggering a pump-down, which evacuates the entire system.

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You see it going down.

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If it's zero, the compressor will also turn off.

Now we put the last closure on the compressor in the back-seated position.

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Now the valve is back in the back-seated position.

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We can remove the hose. We worked completely emission-free.

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Immediate leak tightness check.

We have done an indirect leak sealing test. Next, the set is pressure-tested with nitrogen, and to be 100% sure, we perform a direct leak tightness test.

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