Pipe Diameter Advice

[doitall]

He's gone home now but still adamant 15mm is OK. Another plumber down the road has had a look and said 15mm will work OK but the best thing to do would be to do a flow test.

Can't do that yet...

If we change to 22mm I get the impression we will be paying extra for it....

Lets put it another way, if it works I'll be surprised.

The data for the taps you posted the link says.

Solid brass. Suitable for high pressure systems only.

Ok Grohe said they was ok, I would take that with a pinch of salt.

Out of interest the plumber has priced to do the job, the only extra should be the extra for the larger pipe, and even that is being kind.

 

[securespark]

Granted, Screwfix says the taps are for high pressure only, but the same bumpf lower down also says 0.2 - 5 bar.

That's why I checked with Grohe that our gravity fed HW system would be OK with these taps and they said yes.

I even double-checked on a different day and spoke to another bloke at technical at Grohe and he said they would be OK at 0.1 bar and certainly at 0.2 bar.

At the moment, we have asked the plumber to stop work on the shower cubicle altogether.

The bath installation still has 15mm feeding the HW, so the proof of the pudding will be in the eating: we'll find out later in the week if the bath fills adequately quickly or not.

If not, how does one attach 22mm pipe to the Grohe tap in the link above?

 

[doitall]

I would use a 1/2 x 22mm tap connector.

As said if the plumber say it will be fine then he can replace it at his expense if it isn't.

 

[securespark]

Thanks for all your advice.

I shall see how the flow rate of the bath turns out and if it is poor, shall suggest he rectifies it and see what he says.

Can't say this is doing much for my stress levels.

Tiling is disappointing too, but that's a story for another forum....

 

[doitall]

Thats why I said send him home for the day to think about where he wants to go with the job.

If he's in a mood, it will go downhill fast.

 

[securespark]

The bath tap is on today. Disappointed with flow rate ( as expected ). Plumber tells me the flow rate is one of the best he has seen.

On 2m head???

He tried to tell me there is absolutely no point putting in 22mm because it is restricted at the tap anyway A. by the 1/2" BSP and B. by the tap itself. So, I said, how come it is rated up to 5 bar then?

He even said the 22mm pipe will reduce the pressure: the 15mm pipe is increasing the pressure to the tap.

Now, I'm a sparkie, not a plumber, but aren't pressure and flow rate two different things?

Any way, before he comes back tomorrow, is there a simple test I can do at the bath tap to check whether the 15mm pipe is delivering adequate flow rates?

It takes 10 seconds to fill a 2 litre jug at the bath. Is this adequate for a bath or not?

 

[HERTS P&D]

Mr Spark, you are the customer, tell him you are not happy with the flow and that you want 22mm pipe work.

End Of!!!

Andy

 

[doitall]

12Ltrs/min is that hot and cold or just one or the other.

The pressure will not alter, that is governed by the height of the tank.

The volume is what you should be looking at, so the bigger the pipe the more water will fall out the end, subject to the taps being able to let it out.

 

[Terry lambert]

When I describe to customers the difference between flow and pressure I tell them. If you have a bus and a mini driving down the road at 20mph and mass was flow and speed pressure.

The bus may have more mass but is still driving at the same speed

I had to read that twice, I've gone and confused myself now

 

[securespark]

12Ltrs/min is that hot and cold or just one or the other.

Just the hot. Not too bothered about the cold, it's mains.

Is it OK for a bath??

The pressure will not alter, that is governed by the height of the tank.

So why is he telling me the 15mm will give a better pressure than the 22mm?

The volume is what you should be looking at, so the bigger the pipe the more water will fall out the end.

That description suits my brain, especially at this time.

 

[Terry lambert]

Because you have cold on mains and your hot off of gravity you will have an imbalance of pressure which can cause you some problems on showers.

I would forget all of this at the moment, stop arguing with the tw@t and tell him wrongly or rightly to run 22 to your bath as this is what you want and your paying his wages.

 

[wannocks]

You could think of it as pressure equates to voltage and flow equates to current.

 

[doitall]

So why is he telling me the 15mm will give a better pressure than the 22mm?

The guy is clearly trying to baffle you with bullshit.

The smaller the hole the bigger the jet of water, looks like you have more pressure.

Get him to connect a length of 22mm pipe from the cylinder to the tap and measure the difference, can run it over the floor for the test, I would expect you to nearly double what you get at the moment.

 

[securespark]

A sincere and huge thank you to everyone who has offered us your kind advice.

Considering that the bath is final fixed and tiled/ sealed in place and it will be a real pig to replace the pipe (the tap is wall-mounted and the pipe is under the floor under the bath which is overlaid with ply), Mrs Secure has decided against replacing the pipe, regardless of blame or responsibility.

I am unhappy about this, but with that in mind, is 12l/min an acceptable flow rate for a hot tap for a bath?

Whether it makes any difference or not I don't know but up to a point 2m before the tap, it is run in 22mm then it changes to 15mm.

Thank you.

 

[Terry lambert]

You will only get the maximum flow from your narrowest point and in your case that would have been the 15 mm conections to the tap. (really you should change the tap and upgrade the pipe)

So in theory you wouldn't havegained anything unless you changed the tap to a low pressure one, if in the future you may do this ( good reason to upgrade)

Mrs securespark. I think has the final say and all that turmoil for no gain would not be worth the greif, so for the benefit of marital bliss, let it lay

Good night and god bless