Split systems copper size

[SkyWalker]

my gaffer sent one of our lads off the other day to replace old 22 equipment with 410a using existing pipe runs, he cleaned it all out with endoflush, then went to connect up the new equipment and neither the suction line or the liquid/expansion line were the correct size, basically it was as follows

existing r22 3/4" - 20mm Suction line, 1/2" - 12mm Liquid/Expansion line

New r410a Required 5/8" - 15mm Suction line, 3/8" Liquid/Expansion line.

my gaffer told him to carry on and install it as it would only mean less "friction" so nothing to worry about, now im not completely convinced by this but don't want to question him, lol. would this not affect oil return in suction line? and in liquid line would this cause liquid to flash before it enters evaporater possibly have some sort of effect on the pressure/temp in this line, (i really dont know :-/ )

being a split syatem the Expansion device is in outdoor unit and pipe run was about 30m i believe.

[chemi-cool]

30 meters is a long run for a split unit.
For that distance, consult the manufacturer,
Roughly the pipes diameter are OK,

A small correction about the diameters:

3\4 = 19 mm
5\8 = 16 mm

[SkyWalker]

at what point would you say no, you cant just change the copper tube size? what major effects does changing the sizing actually have? mainly over sizing?

[R1976]

Most manufacturers have details about this instance. You can normally do this but it effects the allowed pipe lengths and duties.

[brunstar]

this iss true, the suction line is not as important as the liquid, you are correct and it will flash off, possible icing of the indoor unit and expansion valve hunting..
good luck, no wonder nothing ever works properly and product is first to get the blame!
what brand was it?

[SkyWalker]

hitachi, seem to run o.k

[kcuk]

ive been onto a job where they used existing lines,

1 was 407c ( loves moisture)
2 never chemical cleaned the system
used existing pipes and didnt even triple vaum system.

they used slightly larger suction i cannot rember now but the units needed more gas as the pipework was a bigger volume.....but the biggest problem is that becuase of the bigger volume of pipework i.e suction line you end up with les velocity in the suction line and the units rely on this to get the oil back to the compressor, so depending on the condeser evaporator positiong you could end up with partly flooded evaporator. so in the summer now it ices up and in the winter it ices up:confused:

[wombat]

The wall thickness on the 3/4" pipe that was using R22 is probably 0.91mm. My understanding is pipe thickness for R410a should be 1.22mm.
Could this be a problem with higher operating pressures from R410A?

[kcuk]

not sure but i did query this before but all the places we goto now sell standard copper wall thickness for r410a but im sure you need to change the pipework even if it is the right diameter.