Repairing a heat pump compressor braze

Corroded brazed joint to an R-22 heat pump:
http://67.207.131.7/poolheater.jpg
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?
Reply to
Richard J Kinch
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I think you could sneak a coupler on that little stub. Time to collect one of those many favors God owes you!
Reply to
Buerste
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.
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Reply to
Bruce L. Bergman
Richard J Kinch fired this volley in news:Xns9C261AB2136someconundrum@216.196.97.131:
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.
LLoyd
Reply to
Lloyd E. Sponenburgh
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.
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Reply to
Bruce L. Bergman
Bruce, what is your line of work? One moment I think you are HVAC, the next moment I think you are an electrician. You are a wealth of knowledge.
Wes
Reply to
Wes
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.
Reply to
Richard J Kinch
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.
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Reply to
Bruce L. Bergman
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 copper:
http://67.207.131.7/poolheater2.jpg 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 geometry.
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.
Reply to
Richard J Kinch
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.
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Reply to
Bruce L. Bergman

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