Vacuum setup

[Damien]

Looking for opinions or different ideasAttachment 258821

[jw-lu597]

looks good to me, but who knows. You could add a fancy micron gauge if you want. Or also use a core extractor tool to pull the vac with no schrader core and then reinsert it after evacuation.

[270wsm]

Damien, could you take a close up picture of the adapter you are using on the pump to attach your 3/8 hoses?

[Damien]

The fitting on my pump is 1/2flare x 1/2flare x 1/2npt

[Chuck]

You are not gaining much by pulling the schrader cores in the system since you are still pulling through the cores in your core tools.

You will pull vac faster if you pull straight through the core tools, so you would have a straight wide open shot into the system.

[jw-lu597]

Most core tools have an auxiliary vacuum port, that you can also pull the core from, seal off, and then return the system core when done evacuating. I don't know about all the fittings that he's using here, but with a standard set of hoses that have just a core depressor, removing the schrader cores in the system is wide open, like opening a refrigeration service valve. Seems to speed up recovery a lot. And makes for a better vacuum, so I've been taught.

[Chuck]

Really? I haven't found this to be true, particularly when recovering. I don't know about all the fittings that he's using here, but with a standard set of hoses that have just a core depressor, removing the schrader cores in the system is wide open, like opening a refrigeration service valve. Seems to speed up recovery a lot. And makes for a better vacuum, so I've been taught.

Yes, it does speed up recovery, but not the way it is hooked up in the pic. He is pulling through the cores in the core removal tool (CRT).

If Damien takes switches the mic gauge to the other port and hooks his vacuum hoses directly to the end of the CRT, he will speed up vac and recovery times.

Also why use 3 CRT's??

[jw-lu597]

Yes, it does speed up recovery, but not the way it is hooked up in the pic. He is pulling through the cores in the core removal tool (CRT).

If Damien takes switches the mic gauge to the other port and hooks his vacuum hoses directly to the end of the CRT, he will speed up vac and recovery times.

I see -- was confused with what you were saying for a second. We're on the same page. That's a lot of adapters. The less connections and restrictions the better.

[Damien]

I removed all schraeders including in the CRTs. I use three for my micron gauge. And nylog on all those connections. Should have gotten a different angle

[Chuck]

Like this.

[Damien]

I'll try just two CRTs on the next job. I agree, less connections the better.

[pacnw]

You are not gaining much by pulling the schrader cores in the system since you are still pulling through the cores in your core tools.

You will pull vac faster if you pull straight through the core tools, so you would have a straight wide open shot into the system.

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

[Damien]

What do you do about those RTU's that have the longer schraeders?

Just braze in regular service ports?

[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?

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