HVAC Installers - Looking for advice on new install

[jdcompman]

Ok, I got back on this project again this weekend. I ordered an 1/2" hose and greatly simplified my setup. Here is a poor picture of the setup...

You can see that I have the micron gauge on the suction line with the schrader valve still installed, since you can see I cannot get the VCT on that line because of the piping configuration. This also ensured that my micron gauge was as far away from the pump as possible. My 1/2" hose is hooked to the VCT on the liquid line with the schrader valve removed.

I hooked this up and let it run for about 4 hours. That got the system down to 315 microns. At this point I valved off the VCT and watched the rise. As soon as I valved off the VCT the rise was very slow. After 10 minutes I was at 580 microns and after 20 minutes I was at 770. After 1.5 hours I was at 1440 and not moving at all.

I'm assuming these results mean that I still have moisture in the system so I'll do a sweep with nitrogen this week and vacuum again to see if I can improve my results. This process has taken forever since I've been traveling for work the last 3 weeks. I think i'm finally on the home stretch though.

I appreciate everyone's input very much and as always let me know if I'm doing something wrong or should be doing something differently.

*edit* obviously I had my VCT open during the evacuation The picture must have been at the 10 minute mark after closing off the system. You can also see I have a leak rate on the micron gauge of 0.4 microns per second.

 

[Trey T]

@ 10min of system isolation, you should have release the refrigerant and disconnect all of your tools.

0.4 micron-Hg/sec (24micron-Hg/min) is 76% below the industry standard requirement - SUPER LOW. The industry only ask 100micron-Hg/min.

What's the CFM rating on the pump?

 

[jdcompman]

@ 10min of system isolation, you should have release the refrigerant and disconnect all of your tools.

0.4 micron-Hg/sec (24micron-Hg/min) is 76% below the industry standard requirement - SUPER LOW. The industry only ask 100micron-Hg/min.

What's the CFM rating on the pump?

Again thanks for the response. I guess I'm done then. I was under the impression that I should be able to pull below 500 and get it to be stable there. Again I think most of this is just not knowing exactly what to expect for a *final* reading.

I have a JB DV-142N pump. It's 5CFM.

 

[Ohmthis]

Great job finding a solution. But, I don't believe you should stop and release your charge just yet. What does the manf. require for the vacuum? Most all want 500 or below. Double check that and decide for yourself. Me I would flow some nitrogen and pump down again. Let us know how it goes.

 

[jdcompman]

Great job finding a solution. But, I don't believe you should stop and release your charge just yet. What does the manf. require for the vacuum? Most all want 500 or below. Double check that and decide for yourself. Me I would flow some nitrogen and pump down again. Let us know how it goes.

Good point! I went back and checked the install manual and it states,

"After the system has been leak-checked and proven sealed, connect the vacuum pump and evacuate system to 500 microns and hold 500 microns or less for at least 15 minutes."

I read that statement two different ways. One way says to just keep the system under 500 microns for 15 mins and your good. The other way I read that says that after valving off the system, it must hold under 500 microns.

One way says I'm done and good to release the charge. The other way says I'm very close but have a little ways to go.

 

[LS6 Tommy]

It means you must hold under 500 microns valved off.

Tommy

 

[jdcompman]

Well I was back at it again this weekend and I'm happy to report that this part of the project is DONE!

I figured a would do a triple evacuation to finish this off. I started out on Saturday with a nitrogen sweep and then an evacuation down to 1000 microns.

After that, I broke the vacuum with nitrogen and let the nitrogen sit in the system for 1 hour. I then proceeded to pull the system down to 500 microns.

I broke the vacuum again with nitrogen. While I was waiting an hour with the nitrogen in the system, I changed the oil in my pump and proceeded to go for the gold and finish this thing off. After 2 hours I was down to 193 microns (my person goal was below 200).

I figured this was good and valved the system off. After the prerequisite 15 minutes I was at 430 microns, well below the factory spec.

I then proceeded to remove my equipment, re-install the schrader valve and open the refrigerant valves. Finally success! Thank you all very much for your tips and help through this learning process. I definitely learned that there are a few small steps I was missing from my research.

Tonight I'll throw the breaker for the condenser to let the crankcase heater start to heat the compressor oil, and tomorrow I should be able to fire it up for a test run.

 

[Trey T]

Good job!!

 

[JackDiddly]

Success!

 

[bruincup]

What a great thread. The knowledge here is amazing.

bruincup