Corroded brazed joint to an R-22 heat pump:
Doesn't look to me like this has enough sound material left to be spliced
back together with a new braze.
Is there any good way to put a new fitting into the side of these
hermetically sealed compressor cans?
There might be enough meat left to work with, but you need to be
gentle with it - don't even THINK about swaging on the compressor
stub, if it splits you are dead.
You need to cut off the steel where it's swaged out to let the
Copper go inside. Clean up and "tin" with silver braze, then put a
larger piece of tubing over the top of steel line and braze it. Use a
swage on the copper tubing if needed to get the right size.
Either that, or get the next size smaller tubing and go inside what's
left of the old nipple. Don't worry about restriction, it works.
Richard J Kinch fired this volley in
Richard, it looks to me like there's enough to do it wrong twice, and
still have enough for a good fix.
You can mount a nipple in a small backer plate, then weld that to the
can, but I don't like to introduce that much heat on the can itself.
Oil, paint, insulating coatings, etc. on the inside may char and end
up blocking a valve downline.
I just had another thought that requires a seperate post - Looks like
you lost some oil when it rusted through. You don't want to waste
several hours getting that system all fixed up, only to have the
compressor sieze on you.
Cut loose both the suction and discharge, and one of the blanked off
process tubes on the side of the can will let you dump the oil out of
the compressor crankcase when you pop it open.
Find a Cut Sheet for the compressor online, they will tell you how
much oil it takes and show an internal diagram and what each tube is
used for. Sometimes they are just alternate suction inlets depending
on system layout - and you might be able to switch over to it...
Some low temperature refrigeration compressors have a loop of tubing
in the crankcase for an oil cooler, and all you'll get is to the other
end of the tube.
Drain the old oil - measure for reference. And if the amount that
comes out is way short, you just saved yourself...
Braze an access valve on that process tube for future use, and braze
the compressor back into the system.
Then get a refrigeration oil hand pump (looks like a miniature
bicycle pump with 1/4" Flare fittings) and a bottle of the right type
(Mineral, PAG, POE depending on the refrigerant) and weight
refrigeration oil, and put in a fresh oil charge.
You can find the oil in quarts so you don't have to get a gallon AKA
Lifetime Supply. The pumps are usually calibrated at so many ounces
per stroke - RTFM. (Yellow Jacket 77930 is 3.8 oz., 77940 is 2.6 oz.)
There might be some old oil still running around in the lines and
coils, but that's okay. A little too much oil in the system is a
whole lot better than not enough.
A lot too much is bad, but you would really have to work at
overfilling it that much.
Good point, although my experience with suction side leaks is that not much
oil is lost, just enough to see.
But now I also wonder how long this system has been open and whether
moisture hasn't gotten in.
Now, Electrican. Before that, General Construction and I brushed up
on my Framing and Plumbing. Two jobs ago, Heating and Air. Oh, and
before that Central Office Equipment installer (Step and Digital and
Power) and Construction Cable Splicer.
And when other crafts are around, I tend to pay attention. ;-) You
can pick up a lot through careful observation.
Sometimes it is nice to know lots about lots.
And you learn what NOT to do, which is far more important some days.
Like mess with old single-wrap paper insulated telephone cable more
than absolutely necessary - there's a real good reason it's called
"Firecracker Cable". Open up the splice to fix one short or cross and
cause ten more...
The wise man says "mark that one pair bad and be done with it". But
the fool wastes a lot of effort trying to fix the un-fixable, and ends
up three steps back from where he started - with a bunch of angry
customers with dead phone lines, to boot.
Well, now here is an update where the owner has cleaned off the corrosion,
showing some sound remnant metal, with the joint being apparently copper to
Here is an idea I had: could one not just wrap this snug with flat copper
braid (like copper grounding strap stuff) and then fill with braze, like a
solid metal "bandage"? Or even wrap with copper wire and fill?
Otherwise I am thinking a sleeve machined to fit closely over the remnant
In any case, brazing will require opening this joint, cleaning off the oil
residue, reassembling with repair parts, filling with inert gas, and
finally heating to braze temp. Then evacuation and recharging.
Pressurize and get out the test soap - figure out exactly where it
is leaking. You do NOT necessarily have to take the old joint apart
if it's basically sound.
If it is a cold braze joint and a channel opened up in the gap after
time passed - take it apart, clean it up, and re-braze it.
If it is a leak in the stub and not a bad joint braze, and I was
making a patch for this, I'd just slit a section of copper tubing and
slide it over the leak Put the copper wire wind layer over the patch
to mechanically hold it, then braze it in place.