Pipes to large for R410a??

[Spanglishsparky]

Hi Guy's

Can I start by apologizing to the "Professionals" in the HVAC industry! I have only fitted R410a & R407c split types AC todate with no problems thus far!

My Problem!

A new pre installation of ducting and piping in a 2 bedroom flat has piping sizes of 3/8" & 5/8" which I can only assume the Spanish builders were intending to fit an R22 system! (Fast becoming obsolete)
My problem is! The client only wants an R410a system fitted and prefers Panasonic (5 year motor warranty me thinks) who can blame him!! but the Panosonic inverter duct type system with R410a has 1/4" & 1/2" connections.

My question is: - Is it possible to reduce the new piping to fit the R410a system by brazing with nitrogen new 1/4" & 1/2" to about 500mm or less before the connection points?
Apart from the extra gas needed because of the pipe size difference and possible gas to liquid problems!
Can this work or will the unit function with less efficiency?

Help would be greatly appreciated!

Spanglishsparky

[coolhandlew]

Couple of possible problems;
there may be a lack of fluid velocity in the suction line preventing oil return to compressor.
The amount of refrigerant you will need to add in order to get liquid to TEV might make it quite scary if someone attempts pump down in future.

[Brian_UK]

Also the discharge line, 1/4", is often part of the expansion line from the condensing unit to the evaporator.

If you increase the pipe size then you may affect the cooling capacity of the system.

[nike123]

Also the discharge line, 1/4", is often part of the expansion line from the condensing unit to the evaporator.


If you increase the pipe size then you may affect the cooling capacity of the system.

Brian, I don't see how that may affect cooling capacity in this case (installed pipe is bigger in diameter)!
In that pipe 90% or more of volume is flash gas, and pressure drop is decreased in comparison with smaller (1/4) pipe.
Problem could be only oil return because of reduced refrigerant speed.
Also, because of higher pipe diameter could be slightly higher heat gain from surrounding then with smaller diameter pipe, but I think that difference is marginal and could be neglected 'cause both pipes are well insulated.

If it is other way around (installed pipe is smaller then required) then it could affect cooling capacity because of higher pressure drop in that pipe.
If I something missed here, please correct me.

P.S. Are you in future now, since your time is already passed 12 AM.;)

[BritCit_Juve]

I would suggest that you look at using one of the systems on the market that can reuse existing R22 pipework (Toshiba Digital Inverter or Mitsi Electric pac splits).
The problem usually relates to the heating cycle and the indoor unit coil getting too much refrigerant. The Tosh units have a switch to limit the output in heating mode to compensate for this larger volume and I suspect the ME unit does too (I usually use Toshiba)
Brit

[kiwifridgie]

sell a bigger unit if your worried. but if the pipe run is not huge, and od unit is lower than id there should be no oil return issues. heating will not be affected to any major degree.

[lowcool]

is the pipe wall thickness ok ??