Beer Line Length Help

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So I've decided to properly balance my beer lines.

For ages I had the pressure at around 16psi (seems a little high now) with 3.3m of beer line, 5mm ID, with the centre of the keg sitting about 35-40cm below the tap. Line runs up into a coil on the inner side of the fridge then traveling around the inside of the fridge to the tap on the door, dropping down about 5cm to the tap.

Occasionaly it would pour the perfect beer, but was always, always under-carbonated, never looked anything like what you'd get at a pub, and a long way off bottled, sugar primed, beers form the same batch.

Re-did my calculations to 12psi with 4mm ID lines, came out to 3m's of length required aiming for a 2.57 volume of CO2.

So I just re-did the lines with 4m (so I could cut it down and account for any aberrations), same height and run of the line, dropped the pressure to 12psi and get nothing but foam. Same fittings, all cleaned, keg is fine, opened it up and re-gased it to 12psi.

Is it because I've started at 4m of length that I get nothing but foam, or is there something wrong somewhere else?

I've tried to rule out over-carbonation. Prior to re-doing the lines it would have been no higher than 18psi. I've released and dropped back to 12, I assume there's probably still 18psi dissolved but I'll check back later after leaving the gas off.

It's all clean, new line, never been used. I'm stumped and a little bit annoyed.
I’d say, if you’ve calculated your line length required to 3m, but ran 4m, you’ll be getting line friction from the extra metre you’ve ran. The purpose of 4mm ID line is for small setups/kegerators where a short line length is desired. Bigger ID, longer length. If you’ve made your new 4mm ID lines longer than your old 5mm ID lines, the you will 100% be getting more line friction.
Well diagnosed Timbo. I gave it a rest while I cooked dinner. Came back, re-did the calculations, realised it was actually 5mm line and cut it back to 2.5m as per a new calculator. Perfect pour.

I was worried this was going to go on for weeks.
From what I have experienced only recently It’s not the extra length and it all sounds like a good tap setup. It has to be over carbonated. I would just turn the gas right down or off and just have enough gas pressure to push out beer for a while or burp the keg a few times.
Sorry for not getting back to this.

watHop - You're right the kegs were over-pressurised, but in the end, not by that much. I did empty them of CO2 at one stage, but they would have still had some residual pressure dissolved. I'm back around where I was pressure-wise, but the length changed from 3.2m to 2.5m. Perfect pours now. The pressure is sitting at 14psi, I think before is was a little higher at 18psi. Taps, temp and fittings remain unchanged.

lost at sea - There was a spreadsheet I found, I'll try and find a link to it and put it on here with the correct credit to the author. From memory it was on these forums. Followed it to a T and everything worked. The only metric I had to double check was middle-height of the keg to tap distance.

Found it - was by a user named crozdog - - scroll down to post number 23 (or updated version in post 26 - thanks DU99)
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