inverter unit pumpdown

[hobbit]

In the process of fixing my flare leak (see the end of
my other thread (http://hvac-talk.com/vbb/showthread.php?t=1110861) ) my tech did something I thought was
... not necessarily impossible, but made somewhat difficult
on the newer systems. He managed to pump down my
Daikin unit and store most of the refer in the outdoor
unit, so we could at least look at the flare and make
sure it was clean and not cracked. There's nothing about
how to do this in the Daikin docs, and of course with the
inverter systems no big old-skool contactor to punch and
make the compressor run. He had me simply ask for lots
of cool at the stat, closed off the liquid valve, and then
when the lineset pressure got down to about 30-40 psig
simply pulled the disconnect and then shut the vapor line.
He said you can't go to zero because the low-press sensor
will kick and cause shutdown and a bunch of solenoids
to open up and lose the pumpdown, so you have to catch
it just at the right moment and it's not perfect. Guess where
the rest of the remaining 410a went when we went to look
at the flare...

Do y'all think this is kosher on the newer style units?
If you believe all the manuals the only way to handle
repairs is recovering the full charge first. I'm still trying
to learn where by-the-book and real life don't agree.

Oh, and this time before letting refer back out of the unit he
actually bought his pump a new bottle of oil so it would
actually pull down, implying that on that first startup we
never got anywhere near enough vacuum on the lineset
to dry it properly. I'm kind of concerned that now there
might be a bunch of moisture throughout the whole
system from that. There *are* a bunch of little filter
dryers scattered around the unit as it comes from the
factory, but why abuse them right off the line?

_H*

[catmanacman]

He should recover all refrigerant fix all leaks replace any driers ( if it has any ) vacuum the system to 300 microns and then weight in a new charge of refrigerant .some mini splits have no filter driers

[mark beiser]

I'm kind of concerned that now there
might be a bunch of moisture throughout the whole
system from that. There *are* a bunch of little filter
dryers scattered around the unit as it comes from the
factory, but why abuse them right off the line?

There are no factory installed filter dryers in your system, nor do they want them installed during installation or repairs on the system.
Those little things "scattered around the unit" are just filter screens.

The good news is that Daikin uses PVE oil instead of POE oil in their R-410a systems.
While PVE oil absorbs moisture even more readily than POE oil, it is chemically stable in he presence of moisture, so it won't break down and form acids.
Unlike POE oil, PVE oil will give up its moisture when the system is evacuated.

Obviously moisture in the system is a bad thing, even if it won't directly cause the oil to break down, but with a system that uses PVE oil, recovering the contaminated refrigerant, doing a proper evacuation, and recharging the system with fresh refrigerant is all that is needed to clean it up.

If the refrigerant lines are relatively short, the system can loose a good bit of refrigerant before it starts having any affect on the capacity or efficiency of the system.
It usually has to have lost quite a lot before the system is no longer able to compensate for the lack of refrigerant and starts reporting errors.

The smaller Daikin systems, like the ductless splits, inverter ducted, SkyAir, and VRVIII-S systems, don't have a charging mode for topping off the charge, so the only "correct" procedure would be to recover the charge, evacuate, and weigh in the correct charge.

[ryan1088]

I agree with Mark, the proper procedure should have been to put into "recover" mode where all the EEVs would go fully open, recover what's left, fix the leak then do the evacuation process all over again. Since you have no idea how much has leaked out and the charge is critical, no reason to not do it the correct way and ward off any evil spirits. Hopefully he knows how many feet of piping he has in the system so the correct charge can be calculated........

Btw Hobbit, you know more about these systems than the guys I work with. Do you need a job?!

[hobbit]

Okay, good to know about the PVE -- the Daikin doc never mentions
anything about oil type one way or the other, and I just assumed it was
POE. Having studied automotive coolant and brake-fluid chemistries
a little too, I'm just as paranoid as the next guy about formation of acids.

Thanks for the clarification on what those little bumps in the pipes are.
They're only about an inch across and maybe three long, copper, and
don't look like the typical f/d. The diagrams do only refer to them as
"filter", seeming to confirm all that.

To work in the field, as fascinating as I'm finding the subject matter from
my armchair right now, I'd need to go through the whole training mill that
the *rest* of my home retrofit certainly isn't going to allow me time for at
the moment. Thanks for that thought, though. Know what I really want?
I want a Boston-north-burbs tech who's as careful as some of you guys
to come out and eyeball this setup, and possibly discuss an ongoing
service relationship. I'm serious about that, and am ready to put down
some real $ to work with someone I can be truly confident in. Someone
who won't be scared off by the fact that even *I* know how to put this
system into all-valves-open vacuuming mode, not that I have any of
the necessary gear to do any of this work or set things right with this
particular system myself. Someone who acknowledges that a homeowner
can determine old envelope heat loss figures, predict new ones, and size
a system accordingly which is exactly what I've done here.

My installer did add some more juice, simply by watching the low side
in cool mode and adding slowly until it stabilized around 150 psig,
and ventured the guess that I'd lost about a pound out of the 5.1 this
rig wants in it. I had no choice but to trust his seeming seat-of-the-pants
experience at that point. It did seem like the lineset was gurgling a little less
when running afterward, so it might have even been a little undercharged
when we started it but hey, these systems have generous accumulators and
should adapt well. The lineset's all of about 17 feet long. I actually own
a leak detector that's so old I don't even remember where it came from, but
it detected the 410A leak just fine and there's no sign of that after the flare
was examined and re-torqued, but no effort to Nylog the thing was made
either even though we actually *talked about that* while the guy was here.

If PMs work here then feel free to poke me, or we can figure out how to
trade email addresses or something. You'd even get to tour all the rest of
the craziness in the overall reno project, which any energy wonk would
have a total ball with.
[*Edit*": I cannot receive PMs on this system. What's an acceptable way
to establish contact??]

_H*

[mark beiser]

My installer did add some more juice, simply by watching the low side
in cool mode and adding slowly until it stabilized around 150 psig,
and ventured the guess that I'd lost about a pound out of the 5.1 this
rig wants in it. I had no choice but to trust his seeming seat-of-the-pants
experience at that point. It did seem like the lineset was gurgling a little less
when running afterward, so it might have even been a little undercharged
when we started it but hey, these systems have generous accumulators and
should adapt well. The lineset's all of about 17 feet long.

Oh boy...

The thing about the system is that it will compensate, within a fairly broad range, for a low refrigerant charge.
They don't shut down and generate an error code until the refrigerant charge is to low for it to safely operate the compressor.

With only a 17' lineset, the system would most likely operate just fine, and at or near full capacity, even if it is a pound or two short of refrigerant.
It could loose half its charge and still happily continue going.

Looking at pressures, especially just the suction pressure, is meaningless when you are dealing with a variable capacity system.

[ryan1088]

Wow, unreal. It only holds a little over 5 pounds and he didn't pull it all? Yikes. That'd be a really long commute from bean town to where I live everyday, haha.

[catmanacman]

Find somebody to come and recover all refrigetant pull a deep vac and weigh in a new charge

[hobbit]

Hmm. That's one of the issues, finding someone who is willing to
do all that due diligence. The guy who installed this rig for me
apparently isn't.

It probably seems like I'm going too hard on this guy, though. For
all I know he's reading all this stuff too. To be totally fair, he and his
helper were here for a week doing all phases of this install -- they
did a great job on all the tin-knocking to get this thing connected
into my existing ductwork, and worked around various issues we both
had finding compatible electricians to get power to it all. He let me
be picky about how to spec and install the HRV, with the understanding
that I was going to do plenty of experimentation with airflows and he
didn't have to declare that part of the job anything like "complete".
I was just a little bothered by what I (and some of you) perceived
as a rather cavalier approach toward certain operations on the heat
pump system itself. Recall that I've been asking for a sanity-check
on that, acknowledging that someone's training being a little out of
date doesn't make them a total f-up on the job. All I want here is a
second opinion (and possibly some hands-on corrective action) from
other Daikin-savvy professionals who can understand where I'm
coming from as the "educated client". I hope there's no harm or risk
of jeopardizing a working relationship from that.

That aside, how 'bout my original question? Is it okay to pump down
an inverter-drive unit in the way detailed above, either on a minisplit
or a ducted unit (which is what I've got, shouldn't really matter) ??
The manuals are all like "never just cut power to the system!" but
apparently their writers haven't lived through New England ice
storms, i.e. like it or not it'll happen sometimes.

_H*

[fritzhvac]

Hey Hobbit !!! :putergreet:
Being you emailed this Nice Comment to my Personnel Email instead of Commenting to the Thread on here generated by another user not me , and Taking the Time to Follow the New Thread after we got the New CTR Appion plungers , and when I tried to respond to your Comment that you Posted to my Personnel Email , your Provider Rejected me , being you don't have your Private Messages on HVACTALK I figured I would Bring it here !!!
I know this does not Pertain YOUR Thread , I am sorry to Post here but I am sure you Wanted my Response , being you took Time out of your Busy Day to respond to me in such a Professional Manner !!!


----- Original Message -----
From: "*Hobbit*" <removed e-mail>
To: fritz
Sent: Saturday, July 7, 2012 12:26:07 AM
Subject: appion

Hi, does this address actually work? I just found your vid on Appion CRT
failures, and could only think that a little analysis could have found
the real issue in a couple of minutes and shortened the video to about
four minutes instead of a half-hour of blind trying about 20 times.

How about this? Have Eddie do a short, to-the-point presentation, since
he was clearly able to think through and pinpoint the problem quickly [but
not until 30+ minutes into your vid], and then you'd have something the
Appion folks could take seriously. Oh, and buy yourself a camera tripod...

_H*

Hey Hobbit !!! :putergreet:

I think we will be just Fine , Appion (Christian) took it Serious enough to mail me 6 more New Plungers , OVERNIGHT after that Video ,with the NEW O Rings at the end of the Plungers ...
and write me a Nice Letter for doing the Video , and the Follow up Video where Me & Eddie are showing them working and Proving that you can pull them down to 20 microns with all my Appion Gear.
You might want to Read the Comments section , where Appion is one of my loyal Subscribers here on Youtube !!!
You might want to Check that one out , that one is 60 minutes Long and I have the Camera strapped to my Dog Sarge Not a Tripod !!! ROFL ...

If you don't like em don't watch em , I have over 200 Videos , and 900 subscibers that Enjoy my Videos , just look at the Comments !!!

My Format is my Format , let me know when you Post your First Youtube HVAC video , and i'll be Glad to give you any Pointers you need , and i'll Steer some of the HVAC Fellers from HVACTALK and on Youtube your way !!!

Oh , I guess what i'm trying to say in a Nice way is , if I want your Opinion i'll give it to ya !!! LOL ... :bump: :cheers:

Take Care ,

Fritz ...










In the process of fixing my flare leak (see the end of
my other thread (http://hvac-talk.com/vbb/showthread.php?t=1110861) ) my tech did something I thought was
... not necessarily impossible, but made somewhat difficult
on the newer systems. He managed to pump down my
Daikin unit and store most of the refer in the outdoor
unit, so we could at least look at the flare and make
sure it was clean and not cracked. There's nothing about
how to do this in the Daikin docs, and of course with the
inverter systems no big old-skool contactor to punch and
make the compressor run. He had me simply ask for lots
of cool at the stat, closed off the liquid valve, and then
when the lineset pressure got down to about 30-40 psig
simply pulled the disconnect and then shut the vapor line.
He said you can't go to zero because the low-press sensor
will kick and cause shutdown and a bunch of solenoids
to open up and lose the pumpdown, so you have to catch
it just at the right moment and it's not perfect. Guess where
the rest of the remaining 410a went when we went to look
at the flare...

Do y'all think this is kosher on the newer style units?
If you believe all the manuals the only way to handle
repairs is recovering the full charge first. I'm still trying
to learn where by-the-book and real life don't agree.

Oh, and this time before letting refer back out of the unit he
actually bought his pump a new bottle of oil so it would
actually pull down, implying that on that first startup we
never got anywhere near enough vacuum on the lineset
to dry it properly. I'm kind of concerned that now there
might be a bunch of moisture throughout the whole
system from that. There *are* a bunch of little filter
dryers scattered around the unit as it comes from the
factory, but why abuse them right off the line?

_H*

[hobbit]

Sorry, it probably came out a little wrong as can often happen in
email. And yes, the spam-filters are pretty strict over here, but
the rejection should have indicated something about why it
happened...

I did go through the whole video, and later found the followup.
Y'all taught me more than I ever thought possible about core
removal tools, in fact, but there were parts in the video where I
was thinking "pull up! pull up! I wanna *see* what he's holding!"
you get the idea. Understood that a hat-cam isn't the ideal
targeting device.

Being the analytical sort that I am, I would have immediately
been digging into the relevant parts going "okay, *why* is it
not grabbing the core, what's it actually supposed to do?"
which might be what you've got some other viewers wondering
for a while too. Well, we all think differently and take different
approaches to a problem, I guess.

This is indeed straying far afield of my original question,
though. Some of it and some of my other AOP questions
boil down to "what shortcuts can my contractor get away
with that I *shouldn't* worry about?" Opinions vary quite
a bit, and I wish I had a better sense of what procedures are
likely to affect the service lifetime of any given system.
Especially the newer ones with much more resilient
control strategy. I really want to have a lot of respect
for the HVAC field as a whole but y'all know there are
some real horror stories out there. What's a homeowner
to do...

_H*