Oil Traps for a small rise on mini split line set?

[TimberMan]

The instructions for my Senville mini say that oil traps prevent oil from running into the compressor and are required every 20’ of rise. It doesn’t clearly say if one is always required, then every 20’ or if none are required if the rise is less than 20’.

In my case I have roughly 6’-7’ of elevation difference between the indoor and outdoor units.

Any advice here will really help! I’ve been practicing my copper flares all day and am ready to go!

Thx

 

[bonneyman]

It's basically because the compressor has to not only push the refrigerant through the lineset but adding a pulling up against gravity. It has a limit to what it can move.
Typically on a home A/C both the indoor coil and condensing unit are above ground level. So a 6' rise on the coil and an 8' rise on the condenser adds' up to 14'. Not supercritical, but a long line distance could cause the friction loses in the tubing to cross the problem threshold. We could always use a larger diameter tubing but there are limits.
Don't know about mini-splits, but the coils are typically ceiling height and the condenser is on the ground. You should be under the 20' maximum.

 

[PCustoms]

The instructions for my Senville mini say that oil traps prevent oil from running into the compressor and are required every 20’ of rise. It doesn’t clearly say if one is always required, then every 20’ or if none are required if the rise is less than 20’.

In my case I have roughly 6’-7’ of elevation difference between the indoor and outdoor units.

Any advice here will really help! I’ve been practicing my copper flares all day and am ready to go!

Thx

If it says required for every 20' and your at less then half that then it's not required for your install

 

[danski0224]

If it says "every 20' of rise" then I would interpret that as needing a trap at 20', not before.

Have not seen residential AC equipment calling out oil traps since R410A was used.

Inverted traps, yes, depending on the installation of a traditional split system. One usually has to find the "long line guidelines" engineering manual because it isn't covered in the "installation manual" any longer.

The safe answer is to contact the vendor for support.

I would not use traditional split system installation practices or "rules of thumb" or guesses or random stranger internet guesses on a mini split.

I personally have not seen oil traps called out in mini split installation instructions for a very long time. Only maximum vertical separation distance and/or an absolute minimum or maximum line length.

 

[pcmeiners]

"If it says "every 20' of rise" then I would interpret that as needing a trap at 20', not before."

Agree, the manufacturers engineer linesets so the velocity of the gas carries the oil along if you stay in the recommended specs, 6-7 elevation is well within spec.

Almost all wall mounted minisplits have an elevation difference of at least 8 feet, from the inside and outside unit.

If you need to worry, concentrate on having a leak free system.

 

[fitter30]

Listed in the install manual max length and rise. What model condenser are you using? Haven't seen traps listed for mini's for years.

 

[TimberMan]

Thx folks! I connected with Senville and they said that no traps are needed for less than 20’ of rise.