Daikin

[daddy33]

Hey everyone, I have just got back into a/c recently after a few yrs just sparking, and am a bit concerned with something one of our office boys has told one of our guys to do. Basically they have recovered a decent Daikin split with a wall mount fan coil, but the original unit that was fitted was running on old R22, the replacement unit is an R410A unit and also different pipe sizes too !! their idea is to use the existing pipe run between indoor-outdoor units but I am thinking of a couple of issues there..

1. Existing pipe run contaminated with R22 oil etc ?
2. When flare nuts taken off old unit they left them sticking up in the air vertically and open totally to full rain downpours for a week or so !

On top of these the pipes are too big, both suction and liquid i think and they were thinking of sleeving them down with a brazed in small length on each pipe to allow flaring on to the condenser coil !

I had heard yrs back that you could sleeve down a size but not up due to correct gas pressures etc.. anyone know if it is correct ?? also would this not change things when after the sleeved down pipe the entire rest of the run would be suddenly a bigger size than the unit was designed to run with ??

I also thought that by not capping the ends on the original pipes that no matter how good the vac pulled, it would not be enough due to the aforementioned R22 oiled pipe and amount of water that could have been accumulated ??

Help !! as I think they are being rough as *%!@ and should replace the total pipe run between units ??

[Brian_UK]

Hi and welcome.

I would stick with you convictions on this one.

Assuming that you are talking about a site on your island then the moisture in the atmosphere contains salt as well.

The pipework could be flushed but is the cost, time and money, worth the effort?

[Greengrocer]

As a general rule I am not in favour or re-using any existing R22 system pipe-work for replacement R410a equipment.
The savings (if any) are just not worth it. There is also the issue of the higher operating pressures with older pipe-work.
I know that various manufacturers are "selling" the idea of replacing R22 kit with R410a and re-using old pipe-work. Carbon scrubbers & "replace technoloy" is all very well and good but in reallity for shortish pipe runs its cheaper to replace the pipe-work than to fart about with the old stuff.
The only possible exception is on a larger VRF/VRV jobs where the pipe-work runs are long & not accessible. Even then I would be very wary about what sort of warranty I would offer.

[Obi Wan]

Hey everyone, I have just got back into a/c recently after a few yrs just sparking, and am a bit concerned with something one of our office boys has told one of our guys to do. Basically they have recovered a decent Daikin split with a wall mount fan coil, but the original unit that was fitted was running on old R22, the replacement unit is an R410A unit and also different pipe sizes too !! their idea is to use the existing pipe run between indoor-outdoor units but I am thinking of a couple of issues there..

1. Existing pipe run contaminated with R22 oil etc ?
2. When flare nuts taken off old unit they left them sticking up in the air vertically and open totally to full rain downpours for a week or so !

On top of these the pipes are too big, both suction and liquid i think and they were thinking of sleeving them down with a brazed in small length on each pipe to allow flaring on to the condenser coil !

I had heard yrs back that you could sleeve down a size but not up due to correct gas pressures etc.. anyone know if it is correct ?? also would this not change things when after the sleeved down pipe the entire rest of the run would be suddenly a bigger size than the unit was designed to run with ??

I also thought that by not capping the ends on the original pipes that no matter how good the vac pulled, it would not be enough due to the aforementioned R22 oiled pipe and amount of water that could have been accumulated ??

Help !! as I think they are being rough as *%!@ and should replace the total pipe run between units ??

Hello Daddy 33

Have a look at the post I entered on
http://www.refrigeration-engineer.co...ead.php?t=7245

It might answer a question or two.

Regards

Obi Wan.

[brunstar]

replace the pipework it will nt be worth flushing it and having an oversized liquid line!

[Odd job]

Any R22 Pipework size 1/2" or 1 1/8" is not thick enough to safely handle the operating pressures of R410a. If you read the small print of manufacturers guides on re-using pipework it should be mentioned. Therefore any claims of being able to re-use VRF R22 pipework (cleaned or not) is bordering on very dodgy info as the two most popular sizes of pipework on R22 systems is 1/2" or 1 1/8"

[Thermatech]

Are you sure about that odd job ?

The data I have seen on copper tube looks ok for up to 3/4 at minimum.

OFN strenght test will exceed any high pressure the system will ever run at providing the new system has operational HP safety switch.

What pressure do you think the tube will burst at ?

Up to 6 hp splits used 3/8 L 3/4 S for most japan R22 manufacture.

Engineer from Jersey said split is wall mount.
So unlikely to be more than 6 hp.

[Scramjetman]

R410a runs significantly higher pressures than R22 (over 1000kPa higher at high outdoor temperatures) so it's unsafe to use the old pipes for the new unit.

If the pipes have been left open for any length of time, there will likely be moisture in them and you run the risk of acid forming in the oil and destroying the new compressor in a short space of time if the pipes are used without careful refrigeration system drying procedure.

Really it is not worth it. It will cost you a packet in the long run if the safety considerations don't hurt somebody before then.

[Grizzly]

Generally I work on bigger stuff but more and more we are getting involved in the smaller stuff!
Smaller being in size only, because as far as I can see it is just as complex!
I have to admit that I have not read everything submitted on this post.
Therefore, say maybe Obi Wan for example.
May have answered my next question.
I would question the fact that older pipes from an r22 system were not capable of holding R410A pressures.
Because in my experience the wall thickness of the pipes has reduced over the years.
Not as some posts SEEM to imply, that the pipes were less substantial!
Or have I read this wrong?
Anyway I ALLWAYS thought the Real problem was the fact of Oil cross contamination.
Having been taught that if you mix mineral with synthetic.
It's a recipe for disaster!!!

Or have I yet again got it wrong?
Grizzly

[Odd job]

Are you sure about that odd job ?

The data I have seen on copper tube looks ok for up to 3/4 at minimum.

I was sure ...... until I checked again .... Delving into old manuals from various manufacturers (from around 1990) it looks as if originally R22 pipe sizes say on 1 1/8" were recommended to be around 1.7mm thick, more than ample to take care of R410a pressures. As you progress through the 90's however the recommendations reduce and at some point (around '97) it becomes possible that 1 1/8" pipework could be too thin to handle R410a pressures.

This still leaves some VRF applications on dodgy ground if your using R410a in pipes designed for R22 but I suspect there's a degree of being over cautious with these things, I still wouldn't risk it though.

You can check any old service/Tech manuals for wall thickness recommendations.

[Thermatech]

Agreed

For VRF systems much more care needed to look at pipe size & wall thickness on tubes 1 1/8 or more.

Having said that it will depend if the tube will have high presssure hot gas in it or not.

For example Mitsubishi City Multi VRF heat recovery system 10hp R22 from from 10 to 15 years old.
The 1 1/8 gas pipe was always the suction gas pipe & never has high pressure hot gas in it.
All other installed pipework was 3/4 or smallerfor that system which was the most common ME VRF system in the 90's.

The latest replacement R410a system is still the same larger gas tube between the outdoor & B/C is always suction gas & never high pressure discharge gas.

But for this thread I am sure the engineer is looking at old R22 wall mount split system with not larger than 3/4 gas 3/8 liquid installed pipework.

Unless the installing contractor used some super thin wall tube not normally sold in the UK then the specification for the tube should be ok for the higher pressures of R410a.

[airmaster]

The line sets should be change. The Daikin system has the exv located on the outdoor unit and when the size of the copper(liquid) line changes the ref. will flash. this will cause the system to loose capacity. Also you are correct that the oil from the R-22 system is not compatable with the 410 system. this system fill fail prematurely.