Professional Member*
Does anyone actually do this? I don't see the reason for it and have been told by some its a waste of time. I've never even seen it done but I've heard people talk about it.
Pull a vacuum and hold your microns. What are yalls thoughts on this?
Professional Member
Its in my school book. But also your right...not many people probably do it. Loll , too much back and forth with nitro and releasing it and pulling another vacuum. It also says to just pull a deep vacuum to 500 microns and then watch if vacuum holds or see if microns go up; indicating there is maybe still moisture in the system.
Professional Member
It's a waste of time and material, IMO.
Don't pick the fly crap out of the pepper.
Regular Guest
It sure is a waste.
Professional Member
In small,capillary refer systems; I find that it does help when I'm having trouble getting to 500 mics. May not be as useful in residential work but has definitely helped me.
Professional Member*
Always do this on freezer equipment. Very dry Nitrogen picks up moisture more easily than straight vacuum and moisture is removed.
Like rinsing out that milk jug before it hits the trash.
Regular Guest
I know right?
Professional Member*
I know for a fact in my area N2 purge is not done. I have had employees tell me they do not. Most don't even use a micron gauge. Its more common than you think. Same thing goes for recovery machines.Originally Posted by dsprice
Personally on my two HP's I installed on my new house this is how I did it. I pressure tested the line set with tracer gas, then leak checked. Each unit had 1 leak. Vented N2 and repaired. Pressure tested again with tracer, no leaks. Purged twice more with N2 then pulled vacuum down to 300 microns. The reason I was so OCD with the N2 was I roughed in my lines about 4-5 months before I installed the units. I did have them capped, but wanted to make sure they were DRY! So Basically I shot N2 through 4 times per system. One unit had about 80 ft of line set.
CT
Professional Member*
Systems that have moisture shows the greatest reward when doing a triple evacuation. It uses a lot of nitrogen but nitrogen is CHEAP and if a triple evac and sweep saves me 45 minutes pulling a vacuum then I'm game.
Sent from my ERIS using Tapatalk 2
Banned
If you can pull a vacuum down to 150 microns and hold for 10 minutes....it's good.
I would definitely recommend appion vacuum rated valve core removal tools....they allow the vacuum to be pulled in 15 minutes on residential systems. And a CPS micron gauge.
Professional Member*
You only need to do a triple evac when your having trouble pulling down.
If you have a very wet system, a slow low pressure purge is the best. if you shoot 400psi thru, it does no good.
Remember, nice, SLOW, N2 purge. then re-evacuate.
If you use a good evacuation setup it is in-fact pretty easy and fast.
Professional Member*
just remove cores before pulling vacuum. After pulling vacuum, add Freon untill about 2 psi, remove hoses and install cores.
Professional Member*
We always break a vacuum at least once with dry nitro after 1000 micron then pull it down again to below 500. Was taught that a very fast vac can make the moisture freeze and the dry nitro was to get it into vapor form. Might have been an old wifes tale but see no need to test the theory for $1 worth of nitro and an extra minute of time.
Professional Member
just had a job with wet system, contamination in the oil due to shietty evacuation. The so called factory expert claimed to have done "proper" evacuation in a day after repairs. We tested by doing oil analysis and megging, and made them redo it, with my guy witnessing. took four days to get the system right. first two and a half were first pull down. System was swept to 1500, broke to 2 psi, 1500, 2 psi, and finally 500. guy thought it was a waste of time too, but when checked again after charging, megger readings went up seven fold, oil analysis clean, moisture indicated very dry. He is now a believer, he says....
Professional Member
Ditto. Seems like these systems always want to hover around 725. Putting a 1/3 hp in in the morning and will be breaking vac at least twice with n2.
Professional Member
Its true. Also can happen with oversized vacuum pump pulling deep vacuum too fast.
Professional Member
everyone is going to say this is not possible
I have repaired at least 5 water source systems this year that had compromised coils, water flooded refrigerant systems. one had been flooded for over 1 year. Zero exaggeration. any amount of moisture can be removed dependent on how bad you want to get it out. im tired of hearing people say that if a line set is open and it rains its ruined. pull vac, break with nitro, and change oil as needed. it will come out.
Posting Permissions
Reply