AC to plateHX Chiller Conversion...56K Warning!

[Naja002]

Apologies, You're right--it is 45% stay-silv and the black paste flux. The 15% is for the copper to copper, no flux.

I've been re-watching some online brazing videos. I think I understand a bit better. I'll have to do some work on it when I get a chance, so progress may get a bit slow for a few days...

[ultralo1]

15% dosent work on steel. You have to have either 45% or 56%. Some come as flux coated rods or bare wire with seperate flux.

The braze only goes where ther is heat and flux. If you did not flux the outside of the female fitting then there will not be any adhesion there.

PS. I have never used black paste flux. If you are using Harris brazing products (stay silv) then you need to be using thier white brazing flux. I have seen people get brazing flux and soldering flux mixed up. I know you did not but I just had to through that in there

[yngndrw]

Hang on, what's this about 15% not working on steel ?

I've used plain copper-phosphorus rods with no flux before on a steel-brass joint and it bonded perfectly well.

Naja002: Good luck on your PayPal dispute.

[Naja002]

15% dosent work on steel. You have to have either 45% or 56%. Some come as flux coated rods or bare wire with seperate flux.

The braze only goes where ther is heat and flux. If you did not flux the outside of the female fitting then there will not be any adhesion there.

PS. I have never used black paste flux. If you are using Harris brazing products (stay silv) then you need to be using thier white brazing flux. I have seen people get brazing flux and soldering flux mixed up. I know you did not but I just had to through that in there

I don't really like the Black flux. It's kind of a dried paste and applies in clumps...if that makes sense. But it's what I bought, so it's what I 've got for now. Here's a link: STAY-SILV Black Flux

I've never used any kind of flux like this before. Not sure if it's old, or is the way it's supposed to be or what.... May just need a good mixing. Maybe the more "liquid" portion has settled to the bottom. I don't know.....

http://www.under-the-ice.com/product_info.php?cPath=36&products_id=94

Naja002: Good luck on your PayPal dispute.

Thanx. It finally arrived today. So, I've closed the dispute. Was going to escalate it at 9pm if the guy had not given me the tracking number. It was shipped UPS, so what's the problem with providing the tracking number? And "shipped" meaning: Yeah, when he got around to it.



Anyway, I guess it's a Happy Day! Ordered the Supco VG64--$151 shipped. Waiting to hear back from John at Frosty-freeze for some odds-n-ends and the N2 regulator finally arrived. So, of course, I had to move to the pressure test! It's been holding just over 250psi for a couple of hours now. The gauge needle has not moved on the High-side. The Low-side is just calling me names:





I won't be able to do anything with it until at least tomorrow, so it will sit overnight and we'll see what happens.


Question: If this thing holds this pressure....Do I really need to mess with the HX joints? As said before--I genuinely believe that the inside of the joints are strong and solid regardless of how the "caps" look.....

[wdrzal]

There should not be a "inside of the braze" or "outside". When both base metals are at the correct temperature it should take ~1-2 seconds to touch the rod and it will flow. The trick is to get dis-simmiliar metals both to the correct brazing temp @ the same time.

None of the brazes on the HX look correct.

[Naja002]

There should not be a "inside of the braze" or "outside". When both base metals are at the correct temperature it should take ~1-2 seconds to touch the rod and it will flow. The trick is to get dis-simmiliar metals both to the correct brazing temp @ the same time.

Thanx, Walt. I understand. It's just going to take some practice for me to get this sorted out for myself.

[ultralo1]

Do I need to "fix" these joints that technically are not broken?

Thats up to you. Use your judgement. Youve earned the right by comming this far on your own.

[[XC] gomeler]

Give the HX a little wiggle and see if any of the joints crack. Don't do this with the system pressurized of course. Biggest problem will be the vibrations from the compressor, hopefully you have a full metal bond.

[Naja002]

Thats up to you. Use your judgement. Youve earned the right by comming this far on your own.

Give the HX a little wiggle and see if any of the joints crack. Don't do this with the system pressurized of course. Biggest problem will be the vibrations from the compressor, hopefully you have a full metal bond.

Ok, I just got done depressurizing it, wiggling it around really well, and repressurizing it. I won't be doing anything on it until tomorrow or maybe this weekend, so it's going to sit pressurized (250psi) unless it leaks.

I think I will work on the caps regardless though....

[Naja002]

Ok, some progress made

I left the unit after the "wiggling" above @ 250psi. It held the pressure for ~24hrs. I depressurized it and set it up to work on the HX joints. I can say that mapp/oxy seems much hotter then just mapp.

The 3/8" is still a blob, but it's in better shape:



The 1/4" line:





I pressurized it back up to 250psi and it held for another 36hrs.


So, I depressurized the system and started to pull a vacuum. 1st round is down just below 500 microns:




Just re-pressurized it to 50psi w/ N2, depressurized it down below 5psi and started round 2 on evacing the system. My plan is to go below 500 microns again, repressurize, and pull a 3rd vac that I may let run overnight. Either way, I plan on going further below on the 3rd vac. I need to find a thread where Walt breaks it down. I'll do that now.....

[wdrzal]

Ya,whats up with the 3/8 in the top picture??????.........The tube is split open on the bend and that looks like it split from internal pressure ??? The tube also looks riffled on the inside like condenser or evaporator tube.

[Naja002]

That's from the flaring tool. I use it to hold the pipe when I swag and it scars the pipes up. Something I was unaware of prior to getting into this, but have read mentioned at least once. It's been there all along. The end of that curved pipe--opposite the HX--is swagged.


Here's another angle from the first set of fullsized shots: Pic

[wdrzal]

The tube still looks split in the orginal picture ???................ why can't I post a pic from "my pictures" any more ? used to be able to click browse ,then click the picture............Now it asking for a URL.

[Naja002]

The tube still looks split in the orginal picture ???................

I agree, but it's not. It holds 250psi and down to 200 microns. It's a macro shot....if that were a penny--you'd be able to see Lincoln's nose hairs..... Plus it's semi-blurry and not the focus of the picture. It looks split in the picture, but it's not. It's just the picture....

why can't I post a pic from "my pictures" any more ? used to be able to click browse ,then click the picture............Now it asking for a URL.

Not sure. I use photobucket and upload to there first. My best guess is that you now have to create an XS album in usercp and upload there...then get the url from there. (or use photobucket or some other photo-hosting site).



I've moved the vacuum guage to the High-side access valve (was on the Hide-side of the manifold). It now shows it's holding a vacuum, whereas before it sure appeared that I was losing some or most of the vacuum....a leak. Pretty wonky the way it was behaving. I'm going to get though this and see about getting some short dedicated hoses for vacuuming.


I've accomplished a few other things....haven't taken pix yet, but I will. Also, trying to sort out 1 or 2 other non-hvac related things.

[art_h]

This is a very interesting project.
I hope I am not too annoying with too many questions.
What is the Significance of 56K warning in the title?
Someone suggested to me that there is a solder suitable for SS.
Mfg: Harris Brand Name: Stay Silver 15 and Stay Silver Flux. Does anyone have any experience with this?
I guess brazing is preferred to solder?
Can anyone comment on the concerns relating to the selection of a brazed plate HX?
The main concern may be that you have the same or better heat transfer.
Can you have too much heat transfer?
The brazed plate HX seems to be much smaller in volume, is this a concern?

[Naja002]

This is a very interesting project.
I hope I am not too annoying with too many questions.
What is the Significance of 56K warning in the title?

Warns people with a slow internet connection that there's a heavy download (Pix)

Someone suggested to me that there is a solder suitable for SS.

My understanding is that "solder" will not handle the pressures involved

Mfg: Harris Brand Name: Stay Silver 15 and Stay Silver Flux. Does anyone have any experience with this?

15% is for copper-to-copper. 45% or above is for mixed metals

I guess brazing is preferred to solder?

Yes

Can anyone comment on the concerns relating to the selection of a brazed plate HX?

Depends on what you want to do/accomplish. My understanding is that the 10 plateHX will handle most to all of what we generally do here.

The main concern may be that you have the same or better heat transfer.
Can you have too much heat transfer?

If the HVAC system cannot handle the load...then, Yes.

The brazed plate HX seems to be much smaller in volume, is this a concern?

No. They are designed for what they do. You just have to spec out what you need.

Answered inside quote....

[art_h]

I have heard that a major problem encountered with brazing, especially SS is that the materials oxidize and prevent good wetting of the brazing rod. I have also heard that purging the inside of the system with Nitrogen (N2) prevents this oxidation from the inside.
Is this a common practice?
Is there a good way of flooding the joint with nitrogen from the outside?

[Naja002]

I have heard that a major problem encountered with brazing, especially SS is that the materials oxidize and prevent good wetting of the brazing rod. I have also heard that purging the inside of the system with Nitrogen (N2) prevents this oxidation from the inside.
Is this a common practice?

Yes


Is there a good way of flooding the joint with nitrogen from the outside?

first 2 pix, post 11

Answered inside quote.....

[Naja002]

Need some help:

The system holds 250psi N2...no problem. But it will not hold a vacuum.

What are the odds that there is a leak in the AC system?

What are the odds that it's all 5 hoses?

What are the odds that this new Supco VG64 leaks?

I've tried every combination that I can think of. Vacuum pump directly to the low-side/vacuum gauge on the high-side, visa versa, through the manifold--low-side only, high-side only, both, valves open, valves closed, vacuum gauge directly to the pump with different hoses and the list goes on. I've spent a lot of hours on this so far.....

I've recently pulled a vac with the compressor running....gauge on the low-side I can get a vac down to <200 microns and it will hold, but once I turn the compressor off....it starts climbing again. Yes, it's the "suction" side, I know...

I have let it evac short-term and for hours. What's wrong with this picture?


I am checking it now with just the manifold gauges. I think it will hold, but we all know how high of a vac that is--not good enough. The only true common denominators are the AC unit and the Supco VG64.....otherwise it's all 5 hoses.

EDIT: Ok, from what I'm reading---it's the hoses.

[ultralo1]

It is not unusual for the vacumm to rise when you valve off the vacuum pump. This is because of the oil in the comp. The oil absorbs the refirgerant. When under vacuum the refrigerant is able to come out of solution and enter the system that is under vacuum, thus raising the micron reading.

Now you are making me get my "refrigeration Geek" on. It would take months of vacuum and heat to get all the refrigerant out of the oil. Since the vacuum only is present at the top most layer of the oil, the refrigerant trapped in the oil at the bottom layer has to work its way to the top layer by diffusion. It migrates very slowly. Some ways to help this along is to agitate the oil mix, shake the comp, bang on it with rubber mallet, etc... "geek" off.

In a system that has had refrigerant in it before, take the vacuum down to less than 200 microns. Valve off the vacuum pump. Wait to see what the micron reading is after 20 minutes. If it is 400 microns or below you are good to go. If it is above 400 then vacuum somemore.

[Naja002]

Understood and Thank You. But that's the problem: the lowest I've been able to maintain is ~1100 microns from 500 or below. That's too much....from what I've been reading. It shoots straight up to 5000, 6000 microns. Generally won't go over 10,000. And this is in a matter of a few minutes (2-4min).

I've tried everything I can think of to isolated the source of the leak. From what I have been reading--it's most likely these hoses. That would actually make the most sense too from what I have experienced.

It will hold a full vacuum according to the manifold gauges, but when I take it down low via the Supco VG64--it won't.

I really don't need to charge it yet. So, I think I am just going to get it full of N2 and take a break from this vacuuming. I've got other stuff to work on first.

But I will have to get back to this, so I would appreciate opinions on what the likelihood is: Unit, gauge, hoses.....

I think I can swing a quick swap-over for the charge--I was looking and thinking about that while I was fighting with this stuff.

What a PITA!

[ultralo1]

Hunting vacuum leaks is systematic exclusion.
Pull the hose off the manifold and test each one induvidially. One end on the vac pump the other end has the vac gauge
If they pass, install one hose on to the manifold center fitting, capp off the other two ports. Pull vacuum on the manifold.
If it holds, then open each side individually, let it pull vacuum then valve off the pump to see if the leak is in that side.

You have just tested the hoses and manifold. Again it is sytematic exclusion.

[Naja002]

Ok, I've already done a lot of what you describe, but I will redo it more systematically as you describe. One problem: the vacuum pump definitely seems to allow air into the setup as soon as it's turned off. I used numerous methods to "isolate" or remove it when preparing to try to hold a vacuum. So, the lack of holding a vacuum described above applies without the vacuum pump. With it---it always loses vacuum when turn off. Didn't seem right, and I guess it's not?

[ultralo1]

I looked back at the other post to see what kind of Vac pump you have. I dont think it has a built in valve to valve off the vacuum. You will need to install an in line valve between the vac pump and the hose. like this
http://www.yellowjacket.com/HVACRPro...&l=4&c=28&p=87

A vacuum pump is not designed to hold a vacuum once it is turned off, in fact it will let the pumps oil be pulled into the charging hoses.

[Naja002]

Thank You very much. I was wondering if the thing was broken. It just seems crazy to me that it's not dealt with by the manufacturer. But I guess this is one of those live and learn things. Makes perfect sense now.

I tried to test a couple of hoses, but gave up pretty quickly. Connected directly to the vacuum pump was a waste of time. So, I tried the blue and red hoses through the manifold-pulling a vacuum then closing the valves....same thing: from 200-300 microns up to +1100 in 60 secs or less. I basically reached the conclusion that it may very well be the supco vg64 that's leaking. But then was definitely open to the hoses also. Seems that these hoses are good for pressure, but not so good for vacuum. I don't currently have the fittings to check the supco without using hoses....so I'm kinda stuck there atm.

I did manage to hold a vacuum more then once. I think it may be the access valve cap on the access port of the Supco vg64. I changed it at one point, but did way too many things to remember. I have plenty of those caps--brand new--so, I will change that cap out and see what happens.