Toshiba VRV Systems

[Martin R]

HI Guys
Have any one been suffering from 5/8 flare nuts splitting on a Toshiba R410a 3 Pipe VRV system according to Toshiba they have not heard of any problems. The system is about 7 years old
Many thanks

[edit] Moved to the correct section.

[Brian_UK]

Probably incorrectly fitted or poor quality nuts in the first install.

[Argus]

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There has always been an issue with flare nuts splitting on components that are liable to frost - hence the restriction on flares fitted to TEVs in the standards - but having said that a VRV indoor set should never frost. so, back to what Brian said.




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[Loops]

I worked for Toshiba Tech Dep UK for nearly 30 years and can honestly say I've never heard a VRF R410a suffering with split flare nuts. So what they told you is correct.

You don't say if the flare nuts are indoor or outdoor.

I concurr with what Brian said, although I think the flare nuts Tosh use are perfectly up to scratch. They might have been over-tighten, hard to say after a failure.

My first boss use to say the correct tightness for a nut was up to sheer and back off half a turn!!!! (He wasn't serious)

Cheers

Loops

[ozairman]

I worked for Toshiba Tech Dep UK for nearly 30 years and can honestly say I've never heard a VRF R410a suffering with split flare nuts. So what they told you is correct.

You don't say if the flare nuts are indoor or outdoor.

I concurr with what Brian said, although I think the flare nuts Tosh use are perfectly up to scratch. They might have been over-tighten, hard to say after a failure.

My first boss use to say the correct tightness for a nut was up to sheer and back off half a turn!!!! (He wasn't serious)

Cheers

Loops

Actually if you have the flare that caused the cracked nut it is very easy to see how tight it was done up.
Get a micrometer with pointed anvils and measure the thickness of the copper pipe in the flared section and compare it to the actual wall thickness of the copper pipe. The flared section of pipe crushes just like a head gasket in a car engine does when it is tightened and provides a witness to torque used.
I am sure Toshiba will have some tables which graph deformation of the copper versus the torque of the flare nut for the various pipe sizes. I know that Fujitsu, Panasonic and Daikin have that sort of information floating around internally. You will probably find that the cracked nuts had their flares tightened more than 50% higher than the specified tension for the size flare.

I did the experiment once on 3/8" flares making up some sample flares as per Fujitsu's R410A product installation manuals and then putting a male flared union in a bench vice and tightening up the samples using a new flare nut each time to various tensions with a torque wrench from 20 - 70 Nm in 10Nm increments. I then marked each flare and kept them handy in my office, it was amusing to compare them with samples of cracked flare nuts and flares that contractors used to send back to me as being "defective". As whenever someone tried to claim for "defective or cracked flare nuts" I would make them submit the actual flare with the defective sample or would not even consider it.

[Makeit go Right]

I heard a while ago from 1-2 engineers that there was something about using soapy liquid to test for leaks on flare joints -- leaving it on the joint rather than washing it off afterwards -- and it would somehow crack the nut, either from combining the cold weather or just.... somehow weakening the metal.

I guess over tightening may be a more plausible cause but anyone know more about the soapy liquid idea?

[install monkey]

taken from page 22 of a tosh vrv manual• Tightening torque of flare pipe connections
Pressure of R410A is higher than that of R22 by
approx. 1.6 times. Therefore, using a torque wrench,
tighten the flare pipe connecting sections which
connect the indoor and outdoor units of the specified
tightening torque. Incorrect connections may cause
not only a gas leak, but also a trouble of the
refrigerating cycle.
REQUIREMENT
If an excessive torque is applied, the nut
may crack depending on the installation
conditions.
Airtight test/Air purge, etc.
For airtight test, air purge, addition of refrigerant, and
gas leak check, follow the Installation Manual attached
to the outdoor unit.
REQUIREMENT
Be sure to use the tool such as charge hose
exclusive to R410A.
Do not turn on the power until the airtight test and
the vacuuming have finished. (If turning on the
power, the incorporated PMV is closed fully and
the period until the vacuuming finishes elongates.
Open fully valves of the outdoor unit
Gas leak check
Check with a leak detector or soap water whether gas
leaks or not, from the pipe connecting section or cap
of the valve.
REQUIREMENT
Use a leak detector manufactured exclusively for
HFC refrigerant (R410A, R134a, etc.).
Connecting pipe
outer dia. (mm)
Ø6.4
Ø9.5
Ø12.7
Tightening torque
(N•m)
14 to18 (1.4 to 1.8 kgf•m)
33 to 42 (3.3 to 4.2 kgf•m)
50 to 62 (5.0 to 6.2 kgf•m)
Re-tightening
torque (N•m)
18 (1.8 kgf•m)
42 (4.2 kgf•m)
62 (

[assailant]

a good reason why everyone should use torque wrenches..

[stufus]

I have previously work for a Toshiba main dealer and about 6 years ago there was a serious issue with a duff batch of flare nuts across all ranges.
The company line is always going to be "deny all accountability".
That said a number of other manufacturers were also affected.
Some of you who deal with Mitsubishi Electric may have noticed a few years ago they started supplying flare nuts with holes drilled just behind the flare face at 12,3,6 and 9 o clock.
This was a direct result of the issues surrounding the duff batch.
The idea was to allow any moisture trapped in the threads to drain out and prevent freeze splits.
I have a few photos of these nuts I'll try find and post later.
PS. never torqued a flare nut and not likely to start now.
Cheers
Stu

[still learning]

had to move a early 410 mitsi wallmount the other day, the suction nut required a 18 inch long adjustable wrench and a smaller wrench with 18 inches of uni strut to get a bit more leverage , i hate to think of the size of the bloke who fitted this system. only seen a few cracked flares , but love my torque wrench

[install monkey]

i didnt fit it as ive never been the jersey channel-so this monkey isnt guilty!