I changed out my 2nd compressor today. At first this was cool, something new to learn. This is turning into a job I do not like to do. After passing a pressure test, I start the evac process. Why does it take so freaking long to evac a system? Even with a 5 CFM pump, new oil and the valve cores removed it still takes 4 to 6 hours to get a 2.5 ton system below 500 microns. I know you guys can't talk politics here, and I was denied access to the professional forumns because I am a "landlord", but a simple yes or no: Am I doing something wrong?
2nd Compressor today
rlmcameron
1 - 20 of 27 Posts
Joined
·
31 Posts
I changed out my 2nd compressor today. At first this was cool, something new to learn. This is turning into a job I do not like to do. After passing a pressure test, I start the evac process. Why does it take so freaking long to evac a system? Even with a 5 CFM pump, new oil and the valve cores removed it still takes 4 to 6 hours to get a 2.5 ton system below 500 microns. I know you guys can't talk politics here, and I was denied access to the professional forumns because I am a "landlord", but a simple yes or no: Am I doing something wrong?
Joined
·
199 Posts
2ed compressor on the same unit? If so you got many other issues need to call a pro.. what was the temp out side? T/E W/nitrogen prob would of done it faster ... either way you prob need to call a pro doubt full you used nitrogen while brazing ... if you brazed it in ... i hope you didn't use soft solder... the flux and refrigerant make a bad acid for the system and gonna make it a 3ed compressor ... either way id say spend a few bucks a and call a pro.. doing it right the first time will save you a ton in the long run... what did you charge it to what was the SH or SC TXV or piston? a 5 cfm pump should get it down quick but also how long was the line set i can go on and on about why it could of took that long but the bottom line is call someone who does it on a day to day so on a 90 deg day you wont have a really really pissed off customer.
No. But this is why a good technician will always be more expensive than a mediocre one. It takes TIME to do things properly and time is money. There is nothing easy about this trade but if you like cursing at inanimate machines its one of the best hahaha
Joined
·
31 Posts
Thank you.
Joined
·
199 Posts
This is very very true. a good tech is worth his weight in gold to a company but any company i ever worked for was mostly flat rate.. trip charge + repair ... dosent matter if i was there for 1 hr or 8hrs was the same price. i know there are company's out there that charge by the hr but find one that is flat rated and has a great rep with the area.
DO it right the first time so you wont have to do it again!
I think the other 2 or 3 dudes missed the point of your post. Yes, changing compressors sucks on most units. Pain in the ass for some of those welds, especially with a unit still full of fresh freon. It can make you a little sick. Landlord or whatever you are. You sound like you are trying to do something right. Very few times have I vacuumed a system and it took less than 4 hours. It just is what it is. The old rule of thumb was 1 hr for every ton of a/c.
Joined
·
2,032 Posts
I wonder what is with the "THUMB" and the HVAC industry.
It will take me at least 3 hours, maybe 4ish most of the time.
I can pull a 10 ton commercial split to less then 500 microns in less then 2 hours. And I'm only using a 6 CFM pump.
Your probably omitting the step that would greatly shorten your vacuum time.
Or flushed the lineset with water.I have a 5 and a 6 cfm pump. On a rare occasion can I get away with 2 hours of vacuuming. It does happen, but most in the 4-6 hr range for anything in the residential arena. Depending on what I'm doing to the system. I'll try to pull below 400 as well. I try to vacuum compressors overnight if I can get away with it.
Joined
·
61,972 Posts
If I am reading the OP correctly... this is what he is asking:
When one changes a coil on a resi system... they pump it down and close off the cond (or HP). The vacuum takes abotu 20-30 min. However:
When one changes a compressor (or service valve), they must remove all the juice. The vacuum takes a lot longer than 20-30 min.
I think the OP is wondering why the difference when one is pulling a vacuum on the whole system as opposed to only the lines and evap coil...
I am not going to answer the question... because I do not want an argument with the mods about DIY... Other than to say: OP: If you are in the Atlanta area, give me a call and we can work out a way for each of us to make a few $$$.
When one changes a coil on a resi system... they pump it down and close off the cond (or HP). The vacuum takes abotu 20-30 min. However:
When one changes a compressor (or service valve), they must remove all the juice. The vacuum takes a lot longer than 20-30 min.
I think the OP is wondering why the difference when one is pulling a vacuum on the whole system as opposed to only the lines and evap coil...
I am not going to answer the question... because I do not want an argument with the mods about DIY... Other than to say: OP: If you are in the Atlanta area, give me a call and we can work out a way for each of us to make a few $$$.
Joined
·
199 Posts
i dident miss the point ... my old robinaire pump will pull a system 5 ton or less down too 500 any where from 15 min too 2hrs if i run into problems and after about 1 hr *very rarely does this happen* i will start a tripple evac to speed up the process an get the moisture out of the oil i have never spent more then 2 hrs pumping down a system.
View attachment 175742
I went to my truck to get this... this is my 4.5 CFM gentle Giant... change the oil after every pump down oil moter regularly will out pump any new 4.5 out there!
Joined
·
3,799 Posts
If I might ask, what micron guage are u using?
four hours is a little long for a small system
four hours is a little long for a small system
Joined
·
2,588 Posts
I believe in triple evacuation with nitrogen because it dilutes the air and water in the system, much like rinsing out a glass that had milk in it. Each rinse carries away most of the residual milk.
I have been considering doing what manufacturers do. Use two process tubes for evacuation and sealing them after the evacuation and hold test. Has anyone done that?
On the production line, they triple evacuate and charge in less than a minute. Of course they have a brute of a vacuum system. Nevertheless, they sure don't do it through schrader fittings and 1/4" hoses.
I have been considering doing what manufacturers do. Use two process tubes for evacuation and sealing them after the evacuation and hold test. Has anyone done that?
On the production line, they triple evacuate and charge in less than a minute. Of course they have a brute of a vacuum system. Nevertheless, they sure don't do it through schrader fittings and 1/4" hoses.
1 - 20 of 27 Posts
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
