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Old 02-20-11, 06:38 AM   #11
mrd
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Vacuum & Bubble test

The vacuum pump was loaded with oil following the instructions. I found with the correct volume of oil, the oil sight gauge still showed low oil after the pump warmed up. I kept topping more up until it suddenly had too much oil, and a small oil mist came out the exhaust. Oh well. I tested the unit by connecting it directly to my micron gauge, expecting it to be able to pull down to 50 microns, as per spec. However, I don't believe it reached anywhere near that.. perhaps in the mid-200s? I forget the exact number, but I decided it was low enough to use (have a million other things to do on this house, let's go!) :P

I hooked up the center hose of my manifold gauge to the service port, and the low-side hose was connected to my micron gauge. The high-side was connected to the vacuum pump. I since have read that the high-pressure gauges aren't designed to be exposed to low vacuums.. It still seems to work fine.

I pulled a vacuum, it reached the high 200s. As soon as I closed the manifold gauge valve it would shoot back upward.. slowing to around the mid 600s iirc. I did this a few times, running it for a good while (20min+) then shutting the valve and letting it rise.

I did not procure nitrogen to use for pressure testing, and for dehydration assistance, despite knowing this is recommended. I did look around at the big box stores for nitrogen, but didn't find any and just decided "oh well let's get on with it" Doh.

The valve for the vacuum pump was closed, the pump shut off, and then the service port valve was cracked. The manifold pressure gauge popped up to around 30 PSI and I then closed the valve. I went around the flares with soapy water, checking for about 5 mins. I did this again around 70 PSI, then around 130-ish? No bubbles.

The next day I did the same for the other lineset, and then I opened both valves fully, finished wiring the system, then let it sit another day. The manual stated to wait 12 hours after connecting the system to power to "protect the compressor."

(I've since realized the suction side of the compressor is likely heated during this powered delay, to encourage vaporization/migration of liquid refrigerant away from the compressor. The compressor can be damaged if it tries to compress a liquid instead of a gas. An accumulator is present in some systems, including this one, on the suction side of the compressor to contain liquids and prevent them from reaching the compressor. The accumulator can get full, however.)

Test run

The next next day I started up the system, tested fans at full speed, tested the heating. It was mid 40s outside. Plenty of heat came out of the indoor blowers. The system was quiet. The outdoor unit fan was plenty strong for being so quiet. There was a small amount of noise from the outdoor unit, the compressor I guess? But very quiet, compared to a traditional outdoor unit.

I started to cover the outdoor portion of the copper lines with insulation, as I hadn't done so yet. The lines were very hot so I shut off the system and at this point I noticed a tiny little bubble slowly form and pop on the outside flare nut. I looked more closely and saw another form and pop.

:\


Last edited by mrd; 02-24-11 at 05:07 PM..
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Old 02-20-11, 06:47 AM   #12
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This stinks, I know I need to fix that flare, and possibly the others. I know I should have done a thorough pressure test. I know I should have insulated the lines first so they wouldn't be messed with after the flares were connected. Ah, with experience comes knowledge :O

To fix the flare I need to get the refrigerant out. I don't have a recovery unit, the cheapest I can find is around $600.. I could call a contractor out, but what will he charge me to recover it all, then come back another day to charge it with a weighed amount? Hundreds, I'm sure..

A little reading and poking through some cobwebs in my head, I determined I could use the compressor to pump down the system refrigerant back into the outdoor unit. The Fujitsu has a 'forced cooling' mode, and so I closed the liquid valves, cracked the gas valves, turned on forced cooling, and watched my gauge. The pressure slowly dropped from 150ish down, down, down... when it was just close to 0psi, I closed the one gas valve, then quick moved the hex wrench to the other gas valve and closed that one too. Then I ran inside and turned off the system.

I considered pulling the disconnect at the outdoor unit, but the Fujitsu instructions for forced cooling just said to press the off button when done, and I dont want to confuse the electronics, if possible, so hopefully an extra 5-10seconds of the compressor running like that isn't enough to hurt anything.

So, this is how the system currently stands. I've just ordered online a nitrogen regulator and an electronic leak detector for the grand total of $100. The magic of ebay. Hopefully they show up this week, I'll procure a tank of nitrogen and do this thing right.

I have my fingers crossed that I haven't lost enough R410A to adversely affect operation. A recovery unit & a scale would be ideal to just charge this with the known proper amount after a proper leak test, but the cost of those items is much more than a hundred dollars. My wallet is getting tight building this house.
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Old 02-20-11, 07:03 AM   #13
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I'm biting my lips, hoping I'm not making any horrible mistakes. I am flying a bit blind, and it can be scary. At the same time, however, I find it hard to believe that a typical contractor would know what he was doing if he came out to assist at this point. I've read so many stories of clueless contractors.
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Old 02-20-11, 07:21 AM   #14
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I should have included this earlier:


I have seen a refrigerant diagram for another Fujitsu system that is nearly identical, but it indicates a receiver between the two heat exchangers in the outdoor unit. I'm not sure if there is one in my system or not, I've read the receiver is where the unit stores the refrigerant during pump down/shipping.
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Old 02-20-11, 08:51 AM   #15
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Wow, I'm glad that I didn't trim my line set. I did not want to do any flares.

Sometimes, a over-torqued flare can last a while. I saw one in thick walled copper
for the water pipe feeding my house. A coupling was installed about 10 feet deep, in my front yard, in 1956.
It started leaking in the mid 1990s...
The flare walls were very thin, like a foot-ballplayer used a long-handled wrench to make them.
I guess the water-hammer got to it..

There was a rock the size of a VW Beetle sitting on top of the pipe, so that
fitting cost us about $1,200 to replace.
The plumber said, they cranked down on the coupling nuts too hard.?.

~~
So, have you done any pressure testing yet??
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Old 02-22-11, 07:30 AM   #16
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Quote:
Originally Posted by mrd View Post
I understand the service port uses a schrader valve. I've got experience with schrader valves from when I used to ride my bike all the time as a kid. And I remember that fitting being very leaky whenever I was connecting/disconnecting something from it. I certainly don't want any leakage after pulling a vacuum. So, I wondered if someone sells a fitting that screws onto a schrader valve, but that has a manual control to depress the core, such that the valve could be closed before unscrewing the fitting. I would think such a thing would exist especially for HVAC work, but I had trouble locating anything. I came across this yellow jacket 18993. I dont know if the 18993 is what I wanted, but I'm hoping. HVACR-Tools.com: Yellow Jacket 18993 Gas Control Valve
I forgot to comment on this - it's funny for a few reasons. I said I don't want leakage after pulling a vacuum - but a schrader seals under positive internal pressure, not so sure about under vacuum.

I did order the 18993 - and it does manually depress the schrader. It has 1/4" connections and unfortunately with the addition of a 1/2"UNF-1/4MFl adapter, it doesn't fit on the Fujitsu. Their service valves only provide a small amount of clearance from the unit body. By the time I acquired a 90-degree adapter, I had also acquired anti-blowback/low-loss fittings for my hose, which lose so little refrigerant under pressure, it doesn't seem to make using the adapter worth bothering with.

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Old 02-22-11, 07:36 AM   #17
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I'm also a bit concerned; I just read an hvac forum anecdote stating 'my experience has been that a vacuumed system pulls close to a pound of refrigerant before getting past atmospheric'. If this is accurate, then that would mean I still have/had about a pound in my lines after pumping back to the outdoor unit. With a slow leak, I don't know if that's all gone or not, and without a recovery unit, I still have no way to acquire that. I don't want to risk damaging the Fujitsu compressor by pulling a vacuum..

I think I may call a contractor after a thorough leak test, to recover & fully recharge.
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Old 02-22-11, 08:41 AM   #18
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I wondered if you tired just re-torquing the connection with the slow leak?

One installer told me to be careful not to over-torque the flares, but crank them up to the spec,
pressure test and add a little bit more torque if there were bubbles.
He said that almost always works. Otherwise, take the connection apart,
inspect the flare and re-flare if needed.. And repeat making the connection.


I've heard that self pump-down actually recovers almost all of the refrigerant.
If the compressor pulled a vacuum on the line-set, I would be afraid that
a leak in the line, would allow air to get into the stored R410a.
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Old 02-22-11, 09:07 AM   #19
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Quote:
Originally Posted by mrd View Post
I should have included this earlier:

I have seen a refrigerant diagram for another Fujitsu system that is nearly identical, but it indicates a receiver between the two heat exchangers in the outdoor unit. I'm not sure if there is one in my system or not, I've read the receiver is where the unit stores the refrigerant during pump down/shipping.
Wow, look at all the thermistors! I'll bet there is another one checking the outside air input temperature too.
Seems like the Fujitsu controller is a more complex system than the old Sanyo..

And two pressure switches at 4-way valve. I wonder why they used two?
Maybe one for detecting over-pressure, and the other was to detect
the pressure in one of the operating modes.
Or perhaps, just a high and low limit pair.?.

When my Sanyo slowly leaked down, I can't remember clearly, but I don't think it shut down at low pressure. Maybe at the end.

I do recall the system the first day of the failure, it was running like normal, but no heat..
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Old 02-27-11, 07:28 PM   #20
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I removed the nut from the leaky flare, and look what I found..



Just as had happened with two other 1/4" flares, it snapped at the base. Maybe I turned the flaring tool too far, maybe I allowed the pipe to stray too far from centered in the nut while tightening. While cutting the pipe for a new flare, I noticed the flaring tool scored the pipe near the cut end. The edge of the cutter was scraping against the pipe.



I needed a straight section of pipe (no curves or bends) and needed to ensure the cutter was precisely perpendicular, not slightly offset on any small crooked part of the pipe. I wonder if this score resulted in a weak spot at the base of the flares..

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