Stainless steel flexipipe vs nylon braided

[AliG]

We have multiple concealed cisterns in the house.

 

They have stainless steel flexipipe as shown here connecting the refill valve to the water supply.

 

https://www.bathroomspareparts.co.uk/porcelanosa-flexi-kit-100306654-189163-p.asp

 

As far as I can see all the makers of concealed cisterns use almost identical pipes.

 

We just had the fourth one fail. One of the four failures causes quite a bit of water damage, the others all failed draining into the cistern.

 

I bought a load of replacement pipes and plan to check them more often to see if they look like failing.

 

Some of them seem to rust quite badly.

 

My suspicion is that the incoming water is quite cold and they are all sealed inside unheated spaces. This causes water to constantly condense on the outside of the pipes and they rust then fail. The local water supply is also very acidic.

 

When you Google flexipipes you get some research from Austrlai that says they are the number one cause of household flooding and account for 20% of all cases of water damage.

 

The one in the bathroom connected to our pool has failed twice. I believe it is because the humidity is higher in this room so more water condenses on the pipes. There is no chlorine. Yesterday it was the flea connector to the mains inside the wall. I managed to replace it with a lot of effort without having to cut the wall open, I did cut the top of the cistern away inside the wall. My arms are pretty scratched up!

 

I found a nylon tap connector and have used this as a replacement as hopefully it is unlikely to rust.

 

https://www.bes.co.uk/flexible-tap-connector-1-2in-x-15mm-x-300mm-17439/

 

I am considering replacing some of the fittings in the cisterns with these. I will buy one to give it a try.

 

https://www.amazon.co.uk/ARCORA-Attachment-Bathroom-Kitchen-Compression/dp/B09PFZ6PL8?th=1

 

It made me wonder why do these normally use stainless steel and not nylon? It seems like nylon braided ones are a lot more popular in the US. The extremely thin and cheap stainless steel in these is always likely to corrode. It also gets dangerously sharp when it does rust and break.

 

Picture of the two pipes I replaced -

 

 

[Mr Punter]

Well I have no idea how you would change these in a full tiled bathroom!  I have 6 at home.

[Nestor]

These have a PVC or EPDM inner tube usually.

Is the hose failing or the fitting?

Is the supply in copper or plastic?

Look as though they have been inside the cistern.

 

[Oz07]

Was that a typo in your original thread about australia? All their loos seem to be connected on a flexible with a tap on the wall. Must be some kind of reg over there? Here a lot of our toilets are plumbed in with fixed pipes. Even my old concealed loo was done with fixed pipework IIRC. Is there a reason they have to be on a flexi? Presume its too hard to change now. 

[AliG]

23 minutes ago, Nestor said:

These have a PVC or EPDM inner tube usually.

Is the hose failing or the fitting?

Is the supply in copper or plastic?

Look as though they have been inside the cistern.

 

It’s the hose that fails.

 

The stainless steel rusts and breaks then the pipe pops.

 

If I look at the pipes the rust seems to be mainly on one side which fits in with my belief it is caused by water condensing on the outside of the pipe.

 

I have PVC piping and then they have used 15mm tap connectors at the end of each piece to connect to the fittings. This is the first time one of those has gone.

 

The main problem seems to be the ones inside the cisterns. They are not under water just at the top of the cistern. All concealed cisterns seem to use a similar connector.

[AliG]

44 minutes ago, Mr Punter said:

Well I have no idea how you would change these in a full tiled bathroom!  I have 6 at home.

The pipes inside the cistern can be replaced just by taking the flush plate off. All of the inside of a concealed cistern can be removed through the flush plate.

 

This was more difficult as it was a second flex connector connecting the valve inside the cistern to the mains.

 

I used metal cutting scissors to cut the top out of the plastic cistern.

 

Then I pushed my arm up into the wall, getting it all scratched up. Yesterday I did this with a small screwdriver to shut off the valve while I waited for a new pipe to arrive so I could turn the water back on. Today I was about to give up because there was no way to get enough purchase on the pipe inside the wall to unscrew the compression fitting.

 

Then I wondered if I could move the 15m PVC mains pipe, I remembered how flexible they are.

 

I pulled it out of the clip holding it to the wall and was able to pull the pipe out through the cistern. Then I could easily unscrew the compression fitting and replace it before putting it back into the wall. The new nylon flexipipe presumably won't rust.

 

Our last house did not use flexi pipes but the builders had put isolating valves in all the fixed pipes entering the cisterns. After around 10 years these all began to fail and we and multiple neighbours had floods due to this as the cisterns were all concealed and you didn't notice the slow leaks until the ceilings started to drip. The flex pipes burst under pressure so you can often hear straight away when they go.

[AliG]

46 minutes ago, Oz07 said:

Was that a typo in your original thread about australia? All their loos seem to be connected on a flexible with a tap on the wall. Must be some kind of reg over there? Here a lot of our toilets are plumbed in with fixed pipes. Even my old concealed loo was done with fixed pipework IIRC. Is there a reason they have to be on a flexi? Presume its too hard to change now. 

Yes Australia, typo fixed thanks.

 

We have a 28mm hot and cold loops in the house with all the fittings connected to this using 15mm pipe. The loop was put in months before the bathrooms so I think they did this as they weren't connecting up the toilets. They just brought the mains close to where the toilets would would be.

 

 

[Mike]

Having once worked in a hotel that experienced at least one connector failing every month - but sometimes every week or more than once on the same day - I can confirm that this is a problem. Twisting them during installation is a known issue, but they do have a limited life even when correctly installed. I tolerate them in a cistern, but have returned to using regular copper pipe elsewhere. Replacement every 10 years is advised if they've been installed.

 

1 hour ago, AliG said:

I am considering replacing some of the fittings in the cisterns with these

Only buy ones that are made to the relevant European / British Standard (sorry - I can't spot the number right now). The standard isn't very good, but it's better than pot luck.

 

[AliG]

The pipe I have ordered is from the US, it claims to meet their standards. I couldn't find a nylon one here for the 3/8 to 1/2 connection. I was able to buy a 15mm to 1/2inch tap connector in nylon here, but It doesn't mention any standards.

 

My thinking is to try it as it is nylon braided and so shouldn't rust.

 

From what I can see nylon ones might be a bit less strong and easier to pinch, but that is pretty much irrelevant as they won't be moving around. One of the ones that failed after just a few years I think might have been twisted during installation.

 

Some places do indeed recommend replacement every 5-10 years. Virtually no one must be doing this in reality.

 

I will certainly check the other pipes in the house, I did this last time I replaced one. Last time I checked there were no other issues and it seemed isolated to certain rooms, it seemed to be all the places where the cistern is on an outside wall and colder, although the cold water coming into the house is pretty cold. It was also the most used cisterns and again I think these have more water running through them so are generally colder.

[Mr Punter]

I hate plumbing.  It is the cause of the vast majority of defects.  I think we should bring back the outside WC.  The hidden cistern is probably going to haunt me.