Undersink plumbing tips?

[MJNewton]

I shall soon be installing a new kitchen and, with it being in a newly-built room, I have a blank sheet of paper on which to design the undersink plumbing and was wondering if anyone had any tips/suggestions about particular items to buy (e.g. I am drawn to the McAlpline double bowl space saver trap kit to maximise space in the cupboard), features to include (e.g. isolators), pipe layouts to ease installation and maintenance etc?

 

One specific quandary I have is whether or not to use the flexi tails that were supplied with the tap (a Franke Athena mixer) as I stumbled across an article that said they account for 22% of water damage insurance claims in Australia houses which made me wonder how good they are. I know they are often regarded as a poor method of supplying individual sink-mounted taps, when compared to fixed piping,  but I wondered how feasible fixed piping up inside a mono tap is? We don't need the stability benefits of fixed pipes as the tap will be mounted in the quartz worktop.

 

In case it is relevant to my options, the unit is a standard 600mm width, the sink is a 1.5 bowl undermount (Franke ARX 160) and there will be an integrated dishwasher adjacent. The water supplies will be coming in via 15mm Hep2O pipes but I am happy to switch over to copper within the unit.

 

 

Edited February 26, 2020 by MJNewton

[Temp]

I like full bore lever valves for isolation. Much easier to operate than other types.

 

Are both hot and cold mains pressure? If not then there are mixer taps with different diameter connections, (bigger for the hot) that can help improve hot flow.

 

I've fitted both flexible and rigid tails to a mono block. The rigid type weren't as difficult to do as expected. I fitted them to the tap and tightened them up. Then splayed them out a bit to allow compression lever valves to be fitted, then made up solder joints and pipes to go between those and the rest of the pipework. 

 

With soldering it's essential to clean pipe and fittings with wire wool and I also wipe on some flux before assembly. Then if they are solder ring type you just apply heat. Sometimes twisting or tapping a fitting helps the solder to flow if you can't see that happening. Almost never need extra solder.

 

 

Edited February 27, 2020 by Temp

[Temp]

I should add..

 

No soldering near the valves as heat can damage the seal, do the compression joints on the valves last. Also do as many solder joints on the workbench as possible leaving just one solder joint and one compression joint per pipe to do under the sink. Do water before waste but mindful of where the waste pipe must go.

Edited February 27, 2020 by Temp

[Carrerahill]

13 hours ago, MJNewton said:

I shall soon be installing a new kitchen and, with it being in a newly-built room, I have a blank sheet of paper on which to design the undersink plumbing and was wondering if anyone had any tips/suggestions about particular items to buy (e.g. I am drawn to the McAlpline double bowl space saver trap kit to maximise space in the cupboard), features to include (e.g. isolators), pipe layouts to ease installation and maintenance etc?

 

One specific quandary I have is whether or not to use the flexi tails that were supplied with the tap (a Franke Athena mixer) as I stumbled across an article that said they account for 22% of water damage insurance claims in Australia houses which made me wonder how good they are. I know they are often regarded as a poor method of supplying individual sink-mounted taps, when compared to fixed piping,  but I wondered how feasible fixed piping up inside a mono tap is? We don't need the stability benefits of fixed pipes as the tap will be mounted in the quartz worktop.

 

In case it is relevant to my options, the unit is a standard 600mm width, the sink is a 1.5 bowl undermount (Franke ARX 160) and there will be an integrated dishwasher adjacent. The water supplies will be coming in via 15mm Hep2O pipes but I am happy to switch over to copper within the unit.

 

 

 

Do it in copper, bend the pipe where possible, solder everything up (add valves after so heat cannot damage them). 

 

The number of cupboards I see where a kitchen installer or "plumber" has thrown in a total mess of plastic pipe and stupid big connections and it takes up most of the space and you are scared to shove anything into the cupboard for fear of knocking the unsupported pipework.

 

For under a sink you can use about 1 length of copper and a tenners worth of solder joints. If you cannot solder then I highly recommend getting a plumber (preferably a gas engineer as they can all still solder). 

 

I am not fussed about solder joints looking beautiful, a few solder snotters doesn't offend me but a quick wipe round with a rag cleans them up and makes them look decent.

 

The result is solid pipework, slimline joints, and it just looks the part.

 

 

[Jeremy Harris]

I'd second doing all visible pipework in copper, even if other hidden pipework is in plastic.  I used plastic for all the long pipe runs, as we had no water on site when I was doing first fix, so I had no easy way to leak test long runs of pipe that would end up being inaccessible.  Where these plastic runs terminated, behind units, I switched to copper pipe, really just because it looks so much neater, plus it's easier to fix so that it's really solid, something that makes operating isolation valve and fitting flexible tap connectors a fair bit easier.

[Carrerahill]

2 hours ago, Temp said:

With soldering it's essential to clean pipe and fittings with wire wool and I also wipe on some flux before assembly. Then if they are solder ring type you just apply heat. Sometimes twisting or tapping a fitting helps the solder to flow if you can't see that happening. Almost never need extra solder.

What he said! Clean clean clean. Also, I like the La-Co flux, it is non acidic so you don't have the old worries of acidic flux being left in joints and eating them over time. It is also handy for longer them work that may not be live for months.

 

https://www.screwfix.com/p/la-co-flux-paste-with-brush-in-cap-125g/61072?kpid=61072&ds_kid=92700048793290397&ds_rl=1249404&gclid=CjwKCAiA7t3yBRADEiwA4GFlI_RF0ft0G1SubltEtdC4mClKiPPV5r8XBbpoTsDn-OX4IFqW8Fea9hoCKzMQAvD_BwE&gclsrc=aw.ds

 

I have dipped stranded wire that had gone near black into this stuff and heated it with a soldering iron and it looked like brand new copper a second or two later!

 

However, steel wool is not actually an accepted method of cleaning under BS EN1254.

 

Plumbers do use it but it was always frowned upon, the issue is if you leave a little steel wire behind it can be included in the solder either fully or partially encapsulated, if the latter then the steel will rust essentially creating a pinhole through the solder, chances are it will be find, but a single strand going through the solder can become a leak fairly quickly (less than a year). The recommended method of cleaning is a wirebrush wheel, or a scotch pad - sand papers and anything using grit is also frowned upon for the same reasons.

 

I always use scotchpads, I have used 1200 wet and dry but I then rinsed the pipe with a little water to remove any abrasive paste (which can act as a separating agent as it will just cook on with the heat). 

 

I will accept, it is all possibly a bit pedantic, but I do see the benefits to not using steel wool so have always just stayed clear of it for this work.

Edited February 27, 2020 by Carrerahill

[Carrerahill]

3 minutes ago, Jeremy Harris said:

I'd second doing all visible pipework in copper, even if other hidden pipework is in plastic.  I used plastic for all the long pipe runs, as we had no water on site when I was doing first fix, so I had no easy way to leak test long runs of pipe that would end up being inaccessible.  Where these plastic runs terminated, behind units, I switched to copper pipe, really just because it looks so much neater, plus it's easier to fix so that it's really solid, something that makes operating isolation valve and fitting flexible tap connectors a fair bit easier.

I'd get on well with you Jeremy!

 

 

[Conor]

I ended up having to completely redo the plumber's work under our kitchen sink. Complete mess. Was a tight space as only a couple hundred mm of space behind the unit drawers.

 

If doing it again, I'd sketch everything out a big sheet of card and use it as a template so I know everything will line up and fit.

[tommyt]

The parts diagram for that tap shows Flexi tails yet the colour photo below shows rigid copper tails. I know for sure that the Franke Minerva boiling water taps changed over to copper tails so perhaps you can buy the tails separately from Franke if the Flexi tails on yours will unscrew? I’d go all copper for under sink without a doubt where possible. 

[tommyt]

Also “space saving” waste kits quite often end up anything but. Depending on your first fix waste pipe location.  

[Temp]

3 hours ago, Carrerahill said:

However, steel wool is not actually an accepted method of cleaning under BS EN1254.

 

Plumbers do use it but it was always frowned upon, the issue is if you leave a little steel wire behind it can be included in the solder either fully or partially encapsulated, if the latter then the steel will rust essentially creating a pinhole through the solder

 

Learn something new every day here. I've always used wire wool but got into the habit of blowing off any wire/dust so perhaps that's why I've not seen this or just been lucky. 

 

There is something very satisfying about assembling copper pipe and just waving a blow lamp and watching the little silver line appear. Equally nothing as frustrating as trying to solder a joint with a bit of water in the pipe.

 

 

[Carrerahill]

15 minutes ago, Temp said:

 

Learn something new every day here. I've always used wire wool but got into the habit of blowing off any wire/dust so perhaps that's why I've not seen this or just been lucky. 

 

There is something very satisfying about assembling copper pipe and just waving a blow lamp and watching the little silver line appear. Equally nothing as frustrating as trying to solder a joint with a bit of water in the pipe.

 

 

I agree, a nice solder job looks so smart.

 

On my first ever pipe soldering mission I think I used steel wool, no flux and ended up with pools of solder on the floor - I have come a long way since then. I taught how to solder pipe by an old gent (who has since becaome a good friend) who explained all the do's and don't and the first thing he banned me from using ever was steelwool! 

 

Yeah wet pipes are a pest, in those circumstances if I must "close" a system with solder joints I solder in a T with a solder on drain valve into one of the ends of the T with the plug removed, this allows the water to steam out.

 

 

 

 

Edited February 27, 2020 by Carrerahill

[MJNewton]

Thank you everyone for the input and suggestions. It is clear we have a lot in common in terms of the importance of taking the 'right' approach! All good food for thought and I will have re-read through to pick out the key ideas.

 

I was considering using copper within the unit, and likely building up the required pipework on the bench before fixing in place and connecting up, and so it was good to see this suggestion being repeated. Even aside from the aesthetics I do recognise the benefits in terms of cost, bulk and likely longevity too.

 

Quote

Equally nothing as frustrating as trying to solder a joint with a bit of water in the pipe.

 

A trick my Dad taught me, which I must admit to have never actually needing to use/test, was to stuff a small piece of bread up inside the pipe. Doesn't need to be wedged in there - just enough to soak up and stop the water flow whilst the joint is made. With the water back on the bread will be pushed out through a tap. I suppose this comes from an era where there weren't fine strainers in taps so they might need to be temporarily removed, although I imagine the bread would break up eventually and pass through.

[Mike]

2 hours ago, MJNewton said:

A trick my Dad taught me, which I must admit to have never actually needing to use/test, was to stuff a small piece of bread up inside the pipe. Doesn't need to be wedged in there - just enough to soak up and stop the water flow whilst the joint is made.

I've done similar using sheets of kitchen roll from time-to-time.

[joe90]

I always use these fir cleaning copper, https://www.toolstation.com/pipe-cleaner-deburrer/p49495