[sowbug]

There is now an even easier way than vacuuming. Instead of pulling the unwanted air and moisture from the lines, you can push it out with another gas, which itself can somehow coexist with the refrigerant. I haven't tried it because I already have the pump and gauges, but if I were installing my first mini split, I'd consider it.

Example: https://www.highseer.com/products/pioneer-kwik-e-vac

[oceanplexian]

It's so ridiculously easy to vacuum and charge a heat pump it's kind of unnecessary.

I think I spent $200 in parts on Amazon and have done 4 heat pumps now. It's a vacuum pump, a scale, and a digital manifold/guage. Punch the numbers for subcool/superheat into a calculator and use the temp probes on the lines where they connect to the condenser and you can even skip the scale.

[seec]

Isn't the problem having access to the gas in the end ? They are tightly regulated, and this is why installers can charge a lot of money, I believe. How did you manage to locate a source?

[sokoloff]

For a typical new install, the outdoor unit contains the charge and unless your lineset is unusually long, you just use that, releasing it with the valves after installing and leak-checking the lines.

In the US, you can get your EPA 508 cert online in a couple hours and buy the refrigerant online. (You need the cert to be legal, but it’s not really checked just to buy.) Tightly regulated is not true in practice. You could buy some in 3 minutes online and have it Monday.

[seec]

Yes, in the US I think it's fine; you have a lot more freedom.

In France, access to the gas technically requires a certification that is not available to regular people. You need to be professional and bow to the bureaucracy.

I know somebody who was required to pay the full installation price for a heat pump he installed himself because there was no professional that was willing to charge and launch the installation for the small fee it should require.

This is the hypocrisy and value-destroying behavior of EU collectivist governments. They tout ecological solutions, but you need to pay far more than is reasonable for those modern solutions. Predictably, people chose things that are worse but cheaper, like wood-burning stoves or pellet stoves.

Those things are made artificially expensive for no good reason, and that's because they get built overseas mostly, and this happened because of regulations in the first place. Then they wonder why the EU is losing ground economically…

[sokoloff]

For your friend’s new install, the refrigerant was in the outdoor unit when shipped from the factory. Accessing that gas just takes an ordinary hex key/Allen wrench. Only if they’d made a mistake and let the refrigerant leak out (or had a ridiculously uncommon length of lineset) would they need access to additional refrigerant.

[seec]

Yeah, I know they come pre-charged now. But I can't remember what his problem was back then. Maybe he didn't know, or he fucked up…

From what I understand, self-install should be fine up to a 12m run, but if you let too much gas leak, you may have issues because of low pressure.

At least now you can buy them for relatively cheap. Mine required a swap of the control board on the inside unit, and it was ridiculously expensive (almost as much as buying a new unit). I am not sure why it fried, but probably bad solder from old age (it's about 15 years old at this point).

It's an excellent technology, but the surrounding business feels extremely shady.

[sokoloff]

s/508/608/

[MisterTea]

My only caution is this method does not let you check if the lines are leak tight.