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Old 10-26-12, 04:08 PM   #21
AC_Hacker
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Quote:
Originally Posted by jeff5may View Post
Can you show some pics of its guts and plumbing for me please, if you still have it?
I'd be glad to. Please let me know exactly what you want to see and I'll post some photos.

-AC

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Old 10-27-12, 07:30 AM   #22
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Guys,
I love the responses I have been getting about the aesthetic appeal of my past projects! Post-apocalyptic? Sub-standard picture quality? Come on now, you're starting to sound like my ol' lady! The topic of this thread is cheap... think rat rod: if I wanted a Ferrari I'd build one. But then I'd have to build a garage for it, too. And shine it up every weekend, and buy some cool sunglasses, and get...not!

These things are orphans, misfits that have in the eyes of any distinguished HVAC serviceman been blasphemed and should be immediately be replaced with a Ferrari (or whatever brand they sell). Pah! I can't be bothered.

Seriously, I hear you. Next time I'll bring my digicam instead of using my phone. When I build a unit that I can call done, I'll make it look nice. But I still like rat rods.

AC,
I'm mainly concerned with the reversing valve and its plumbing, as well as how the txv is rigged. Does it have 2 metering devices, or only the one? I have a similar unit, but it is cooling only. I hope to turn it into a DIY mini-split because it worked so well while I was using it. The unit I have is assembled similar to yours. It looks like it would be fairly simple just to separate the top from the bottom and connect the half-units.

Something I have learned doing research on these portable/room units is that they use the same coils whether they are heat pumps or not. The heat pump units just have different controllers and extra parts for sensing and flow control. That's kinda how I got the idea for this project, because I wasn't sure if the evap coil would hold up to the increased pressure without popping. It seems to me that some of them can't, considering xringer's experience with his first mini-split.

Last edited by jeff5may; 01-31-14 at 10:47 AM.. Reason: grammar
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Old 10-27-12, 09:12 AM   #23
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Woo hoo! One of my scrapper buddies called me this week and said I could have some guts out of a heat pump he ravaged. Cheggit out:

The unit was a Lennox HP25 dash whatever, rated 2 1/2 tons, but a quick lookup of this valve says 1 1/2 tons. Go figure.
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Old 10-27-12, 05:38 PM   #24
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... I wasn't sure if the evap coil would hold up to the increased pressure without popping. It seems to me that some of them can't,considering xringer's experience with his first mini-split.
I wouldn't worry too much about that. I think Xringer would agree that his unit had a pinhole leak from birth.

I'll take the photos & send them on...

-AC
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Old 10-27-12, 10:14 PM   #25
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Quote:
Originally Posted by AC_Hacker View Post
I wouldn't worry too much about that. I think Xringer would agree that his unit had a pinhole leak from birth.

I'll take the photos & send them on...

-AC
Nope, I don't agree. The system was working fine for about a month.
After it failed, I pumped in some nitrogen and easily found the leak,
because it was hissing pretty loud.

I was able to let the Sanyo service manager hear the sound via telephone.
Within seconds, he agreed that I had found the leak and said he would ship a replacement for the outdoor unit.


Bad control firmware causes the Sanyo 24KHS72 to run at overly high RPMs,
until one of the safety limits kick in. (Over-load or Over-pressure).

R410A runs a lot more pressure than standard refrigerants.



After a while, it was most likely one of the many high pressure runs that blew a pin hole
(weak spot?) in the copper tube right above the compressor.

The bad firmware problem is still there, but I now limit the current to 10A.
So my Sanyos* don't even get to try for that 3.6 kW surge anymore..

* Both made in 09/2009
http://i46.photobucket.com/albums/f1...r/NCL/F106.jpg


That's my story, and I'm sticking to it..
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Old 10-27-12, 11:25 PM   #26
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...After a while, it was most likely one of the many high pressure runs that blew a pin hole (weak spot?) in the copper tube right above the compressor.

That's my story, and I'm sticking to it...
OK, I misunderstood the history of the failure, but I disagree with your explanation of the mode of failure.

I seriously doubt that a properly brazed joint would exhibit a pinhole leak, even under conditions of fatal stress. In fact, if all of your joints were properly brazed, it is more likely that an overpressure failure would have resulted in burst tubing.

Pinhole leaks are very a common failure of improperly brazed joints... usually a result of excessive pressure of inert purge gas during brazing. But they can also result from dirty joints, contaminated flux, or insufficient heat.

I suspect that you bought a unit with a joint that had a hidden pinhole defect, that was not quite 100% through, and that the pressure and vibration of use caused the hidden defect to manifest.

* * *

I maintain that our erstwhile EcoRenovator should continue fearlessly on.

Best Luck to him...

-AC
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Old 10-28-12, 12:32 AM   #27
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"I seriously doubt that a properly brazed joint would exhibit a pinhole leak"..

There was no joint. There was a brazed area where the pin hole appeared,
but it was to fasten a copper sensor holder tube, to the refrigerant line.
See the pics at: http://ecorenovator.org/forum/geothe...html#post15830
The location of the pinhole was verified within a few mm..
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Old 11-03-12, 12:01 PM   #28
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x and ac,
This seems to be a trend in the residential HVAC industry. The manufacturers are using thinner wall tubing in their units. Not such a bad thing in the heat exchangers, since thinner walls transfer heat more easily. But as in x's mini-split, the plumbing has also been lightened in order to shave costs. I was reading that with the newer R-410 units, they are toying with smaller diameter, thin-walled rifled tubing to increase surface area and reduce material costs even further! Now how am I going to braze stir-stick sized tubes together in five years?? It doesn't seem like any of this is being applied to commercial equipment. Which brings me to my next point...

Fellow hackers, when you go to home depot or lowes to get copper piping, remember to get the stuff rated for refrigeration / natural gas. It costs a little more than the ice maker line, but it is well worth it. I bought some of each, just to try using the cheapie stuff, and unless you're using the piping for straight runs, the thin stuff is near impossible to bend, flare, or swedge. Brazing it is difficult, it wants to warp and melt. In contrast, you can bend the real stuff by hand without kinking it as long as the bend isn't very tight. Brazing is ten times easier and the filler rod sticks to it better. You can make your own adapters out of it, since it will expand 2 sizes up without cracking. I have determined my time and sanity is worth way more than the difference in price.

Speaking of brazing, a little advice. Unless you're only going to be doing a miniscule amount of brazing, don't buy one of these kits:

They are cheap up front and available all over, but they are too small to braze anything over 1/2" easily. And the fuel gases are outrageously expensive, especially the oxygen. A 10 dollar bottle of o2 holds only 1.3 ounce (1 cubic foot) and will last you about fifteen minutes. Guaranteed to run out halfway through a joint. You will go through about 20 bottles of oxygen for every bottle of propane or propylene (no longer MAPP).

Instead, buy one of these sets used for the same price. Or beg or borrow one from a buddy. Any skilled craftsman will have something similar. These things and their big brothers built the world as we know it.

If you're lucky, the kit will have some gases remaining in the cylinders. If not, you can have the cylinders refilled at your local welding supplier or appliance parts store. The cylinders all cost around 25 dollars to refill, and the smallest o2 cylinders hold 20 cubic feet. You get 200 dollars worth of bernzomatic bottle oxygen for 25 bucks. Moreover, acetylene burns hotter, allowing you to use a smaller flame to do the same brazing. This means the gas you have lasts longer.

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Old 11-03-12, 03:01 PM   #29
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AC_hacker Wrote:

I suspect that you bought a unit with a joint that had a hidden pinhole defect, that was not quite 100% through, and that the pressure and vibration of use caused the hidden defect to manifest.

I helped my brother repair a fridge he was given. The fridge looked new but it had a leak. The appliance business that had sold the fridge to the family gave them such a hard time with the warrenty repair that they just went out and bought a new one. A family needs to keep their food refridgerated. He was given the fridge just to get rid of it.
We just used a little propane to find the leak. The leak was located in one of the bends in the aluminum evaporator. As the bend was made the material thinned out so much the vibration and pressure cause a little pin hole. My brother ordered a new evaporator and we brazed it in with silver solder. (it flows a little better than silphos) The aluminum evaporator had short fused copper tubes for connection.

To charge the fridge with freon I had a modified propane bottle (trick I picked up from AC_Hacker) that I pumped down a old window shaker and installed the gas in the refridgerator. My brother was amazed. Recycling at its best. He had a like new fridge for $80.00.

Point is: The forming of tubes are not infalible. Some wall thinning can occur and over time a hole can develop.

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Old 11-03-12, 06:35 PM   #30
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Quote:
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Speaking of brazing, a little advice...
Hey, glad you're making progress.

I used a MAP gas turbo torch, no oxygen, Silphos... worked good for me.

Whatever tool that works for you is the right tool.

Sounds like you are gaining all the skills to get on with your project.

If there's anything you think was left out of the 'Manifesto' thread, give me a heads up and I'll edit it in.

Good luck on your project!


-AC

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