Vacuum setup

[Chuck]

Try explaining this to mfrs, Lennox, that do not allow the use of CRTs on most resi equip!!!! http://hvac-talk.com/vbb/images/smilies/gah.gif

We are a lennox dealer, and I haven't heard this. What is their reasoning?

[pacnw]

I meant that they are manufactured so that cannot get the CRT on one or both service valves.

[AiResearch]

You can also evacuate without a core removal tool.

- pull schraders
- evacuate
- when evacuation is complete , open liquid service valve and allow pressure to reach 5 to 10 lbs on low side , then re-close liquid valve
- if package unit or system void of refrigerant then add charge to reach the 5 to 10 lbs then stop
- remove hose , place thumb over port and then quickly install schrader
- little refrigerant is lost

Just another option

[Chuck]

I meant that they are manufactured so that cannot get the CRT on one or both service valves.

Ahh yes, now I see what you mean.

[socotech]

I like to have my micron gauge as far away from vac pump as possible. Also, I leave the cores in. My core removal tool works great on core replacement of a "pressurized system". I would not trust that it is tight enough to pull vacuum through.

[Damien]

I like to have my micron gauge as far away from vac pump as possible. Also, I leave the cores in. My core removal tool works great on core replacement of a "pressurized system". I would not trust that it is tight enough to pull vacuum through.

Aside from adding a service port somewhere on the system, right off the CRT is as good as it gets. Heck I suppose a guy could try put the gauge at one service port and hoses on the other?

Brainstorming... Is there a way to test the vacuum capability of a CRT? Putting my vacuum hoses on one CRT and a coupler at the female end of CRT with my gauge on it? When it pulls down I can blank off my pump, see what it holds.

[dsprice]

Where and how are you blanking off?

Sent from my ADR6350 using Tapatalk 2

[Damien]

The JB pump has an isolation valve right on it, turn the knob 45* and it's blanked off.

[jw-lu597]

Lots of good ideas with this thread, and lots of things I'd like to try. To be honest, I usually just evacuate right through my gauges and right through the cores though, just because I'm in a hurry and also when I know the system should be fairly good (i.e. little or no exposure, same day service, no burnout, etc.)

[JTCHVAC]

Here is my question. When you go to put the schraders back into the service ports using the VCRT how do you keep that small amount of air from entering the sytem?

[270wsm]

Here is my question. When you go to put the schraders back into the service ports using the VCRT how do you keep that small amount of air from entering the sytem?

Charge the system first.

[JTCHVAC]

Charge the system first.

Facepalm

[JTCHVAC]

Here is my setup