braze mini-split vs flare connections ?

[junkhound]

About to do first mini-split. Have done split units and always N2 fill and braze.

Approach envisioned for mini-split (410A) is to cut the flare connections off and 15% Ag silphos braze, adding a bidirectional filter dryer and moisture indicator in the process.

Opinions? Is this a wasted effort -- e.g. do mini-split flare connections have a good track record.
Last flare I used on HP (R22) was on a 7.5T carrier HP 30 years ago and was not happy.

[jtrammel]

The exv on minisplits are very small and the smallest piece of trash will make it malfunction. A drier is not recommended either, they are critical charge units and a drier can make it malfunction. best to use flares for mini splits and not risk screwing it up. Read and follow manufacture reccomended procedures IMO

[FrostyBeer]

The few I have done I've always cut and flared them because thats what I've been told from a mr. slim class.

They don't want any brazing due to risk of oxidation and contaminants because there is small strainers in the units. BUT if you flow nitro I don't see an issue but that's my 2 pennies.

[gravity]

DO NOT install a drier on the lines. if you braze and purge nitro you will be fine with your method.

The company I'm at uses all hard pipe and fittings with these units. nitro purge is a most when brazing.

[t527ed]

have always used the flare fittings, only one failure i can remember was years ago on a sanyo unit when the flare nut split.

[Steveo86]

i have gone to a few Fujistu courses and they have said if you weld the warranty is voided

[monkeyspanners]

If its a wall mount i usually cut them off and braze them, then you've only got flares on the outdoor unit where its easy to check, the pipes are then easier to run through a wall or behind the unit without the bulk of the nuts etc. But it depends on the make, some units have little straines just after the flares so you can't cut these.

No driers or sightglass, its an expansion line not a liquid line. Insulate both lines or it'll sweat. Measure the lineset as you go, and calculate the charge by the oz per foot/grams per meter chart, can't use subcool superheat with these.

Best advice i had when starting to fit these is read the instruction before you start, they often bring out slightly different models or change the spec etc and it will catch you out otherwise.

[david912]

we have a city multi going on now, 19 Ah and flares on everything



thats the main Bc controller, theres also a sub bc controller, Alot of flaring!! i feel like a pro at flaring now. make sure you have the right flare tool and oil your tool and copper while flaring. The less brazing you do the better, nito is a must if you have to. No driers or sight glasses. They dont want brazing bc the system dosent have diers and driersshouldnt be installed

[pacnw]

flares only, no flames on minis!!!!!!

I have not seen that it voids warranty, but makes sense.

they are trying to idiot proof the install.

have not had a failed flare in our company, that I am aware of, in the approximately 400 units installed by us.

[mattt787]

i went to a city multi class they said to flare only no brazing they want a presser test up to 600 psi on there system and oil tool and copper

[chuckcrj]

i went to a city multi class they said to flare only no brazing they want a presser test up to 600 psi on there system and oil tool and copper

We flare everything except on the branches that we run multiple heads on one branch. Where they tee off I flowed nitro and brazed them. Yes, pressure test at 600 psi for 24 hours. Then hold <500 microns for 24 hours.

To the OP, make a good flare and it will be just as good as any braze joint. When people have trouble with flares, it is invariable due to a poorly made flare.

[junkhound]

Thanks guys, learned some things about mini-splits.
Will stay with the flare and do the 600 psi N2 test and 24 hr vac also.

[kdean1]

At the recent Mitsubishi Diamond Contractor class we asked about brazing. The instructor said there is no objection to brazing provided proper procedures are followed - clean the joints, trickle nitrogen and use 15% silver content solder.
However, he said flaring should not be a problem if a good flaring tool is used and a torque wrench is used for tightening the flare nuts. Also make sure to use the flare nuts that come on the equipment, NOT hardware store flare nuts that cannot withstand the pressure of R410-A.