500 microns

**phosgene** · 03-15-2005, 10:27 PM

friday night, late at nigtht, middle of nowhere, have to open up a system, lets say heat pump split, no drier to replace old, so you throw on the vacumm pump get it down to 500 microns and lets say it sits at 560. no leaks, no moisture. what would the new drier have achieved (other than maybe 60-100 microns). was anything lost on this job by not having the new drier. proper evacuation was met. any constructive input appreciated.

**pulse21** · 03-15-2005, 10:48 PM

I would have put them on emergency heat untill Monday. The drier is definattly a good insurance policy. So many factors to account for length of time system open, humidity,etc. That is not 100% by the book but you did a thourogh job with the vacum so I would feel good about leaving it as is. I know somebody will probally slam me for this, but if everyone is honest, they have fudged some too. I have changed some Lennox indoor TXVs in the summer late at night to get cooling on and sure was not spending all night messing with it. If you have mot been at this very long you will learn, the book is great but you have to make some exceptions every once and a while.

**tinknocker service tech** · 03-16-2005, 06:38 PM

pulse couldnt say it better
a dryer is a good idea and should be on the system for many reasons. we all know how to kindalike push the rules. late at night working all day and verry tired all you want is to go home. i probably would do the same thing knowing the odds of having to go back are slim. maybe not by the book as they say but still to standarts.odds are if there was anything of concern in the system it would show on you gauges with in the first fifteen to twenty ninutes of running.

**HVAC Pro** · 03-16-2005, 06:45 PM

Here are my thoughts. If you had to braze anything on the system and didn't purge with nitrogen during the brazing process, the residue from oxidation will be flowing throughout the system with the refrigerant and may/will eventually plug something. Probably either a piston or txv. If there wasn't any welding and the system was left open only momentarily I would feel fine about it, having obtained 500 microns. But it really doesn't take that much more effort to both purge and install a drier.

**-80guru** · 03-16-2005, 07:57 PM

What could wrong?? Well one day someone else from your company or some other company will perform service on it and notice no drier and then the HO will get an ear full about the hack that doesn't know about the system needing a liquid line drier or worse you go back a couple of years later forgetting you left out the drier and you start telling the HO about the lousy hack that left out the drier and thats what caused the compressor to go titts up LOL

.

**rimek** · 03-16-2005, 08:21 PM

I think Phosgene's talking about leaving the old drier installed, not taking it out, right? It's better than the usual - leave the old one in AND install another somewhere else- I'm amazed how many times that happens.

**airworx** · 03-16-2005, 09:30 PM

lest you were smart enough not to install a suction drier.

**phosgene** · 03-16-2005, 10:43 PM

thanks for the input. yes I left the original drier in as I had no close replacement. gas had leaked out at liquid line connection to outdoor unit. had to remove connection add new teflon o-ring and tighten, nitrogen pressure tested to 100psig, then vacummed to previously mentioned levels and recharged. no brazing. but like everyone has mentioned the "book" says change drier. I always assumed this was to help you get to 500 microns. but?? if you get to 500 microns anyhow.

**Steve Wiggins** · 03-16-2005, 10:52 PM

Sorry phosgene our industry is set up so we can't do the right thing even if we wanted to. As soon as you take the time to be the good guy your boss will chew you out for taking too long. If you are the boss then the customer will chew you out for being too expensive......damned if you do and damned if you don't. Learn the rules but sometimes you just have to say screw it and go with what works.

**-80guru** · 03-17-2005, 06:22 AM

Oh! sorry I misunderstood. In that case your cool, no problems leaving it in with the precautions you took.

**fat eddy** · 03-17-2005, 06:36 AM

No big deal,

Filter dryers are necessary for their ability to physically block foreign mareial , just as much or even more than their ability to dry out the system,

which is something that a good pull down does anyway.

Only problem you would see is if the dryer was actually broke or plugged.

They recommend replacing them, because they sell them.

Thread: 500 microns

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