Sanyo 24KHS72 AC/HP DIY install project

[AC_Hacker]

Originally Posted by Xringer

Found a place locally that sells this 2-stage pump..

Robinair 15150 Vacuum Pump, 1.5 CFM, Two Stage, 110V

Robinair 15150, 15300, and 15500 1.5, 3, and 5 CFM VacuMaster Vacuum Pump - on Sale at the Test Equipment Depot

They have a pretty good price, even with the taxes..

I think this should be a pretty good unit. If you were working at HVAC for a living, you'd want to get a paying job done as fast as possible, so bigger would definitely be better, especially so if you were working on large systems. But as it is, a smaller unit should be just fine.

The 'vacuuming times' page you cited gives times "as a guide". Since your pump will be on the smaller side, your pump-down times sould be longer, by what factor, I'm not quite sure.

...and as food for thought, I have heard that HVAC techs may, in the middle of a pump-down, close the appropriate valves, change oil, turn on the pump and re-open the appropriate valves and continue on to finish.

A manifold gauge set would give you the valves to do this.

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Should you need to make up some special fittings, just to save you some grief, I'll share a lesson from a previous experiment. I needed a very small valve to manually control refrigerant flow, so I went to my local big-box retailer and got a needle valve that had compresson ring fittings. I hooked it up, torqued it appropriately, went on with my work, only to watch the compression ring fittings leak like like crazy. My guess is that they were meant for non-refrigerant use, like water or something, and when the rapidly expanding refrigerant hit them and chilled them to some ungodly low temperature, the copper shrank away from the compression ring. I mean I really had a mess on my hands!

Only use brazed fittings (although they refer to these as 'sweat fittings' in the trade, don't be fooled into thinking that you can sweat solder them), or flare fittings.
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Best Regards,

-AC_Hacker

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