Poor FLOW. Is upgrading to 22mm worth it? (Ed.)

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tommy8884

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Moderator's note: This is FLOW not pressure
Im in the middle of a bathroom renovation. We have fairly low pressure in our system, with 15mm pipe work. We get just under 10l per min at the kitchen tap on cold. To be fair to our combi (40kw Worcester Bosch), it delivers the same 10l per minute in hot water (just a tad less).

So while working on the soil stack I've noticed our incoming main is actually 22mm (possibly bigger, I cant get the callipers in there). It immediately goes down to 15mm and through the wall to a meter (was moved recently). I could upgrade the pipework to 22mm, it looks like the meter will take the 22mm pipes and run that all the way to the bathroom above and make sure the feed to the boiler gets 22mm up to where it branches off to the boiler. My thinking being that I'm increasing flow up to the points where it splits off to other feeds and to the boiler.

Question : is it worth doing this, and will it actually make any difference.

1720434998462.png


1720435057037.png
 
managed to get my camera in there. Its a black plastic incoming pipe, and is 26.4mm OD. Does raise into question why its bonded above, but i wont let that distract me. House was built in 1967. A bit of googling tells me this is Black Alkathene pipework. Not sure how i connect to that, i can only really find connectors for MPDE pipes

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Elsa TLC said:
What are you getting on the cold main?
Bar & L/pm
Click to expand...
I haven't got anything to test the pressure. But the kitchen tap is the first thing after the meter (granted it goes through a few elbows and 2x stop cocks). I get 10l per min there. I could test at the drain down point I guess.
 
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Upping 15mm - 22mm won't help.

If your only getting 10L on the incoming then that's all you will get.

Check to see if there are any restrictions. Check all inline valves are fully open.

You do have other options!
 
Just throwing in.

Round me the copper pipes are rubbing on stones in the ground and bursting.
People are having new 25mm plastic pipe run to house and water pressure and flow is amazing compared to 15mm copper pipe.
 
Wayners said:
Just throwing in.

Round me the copper pipes are rubbing on stones in the ground and bursting.
People are having new 25mm plastic pipe run to house and water pressure and flow is amazing compared to 15mm copper pipe.
Click to expand...

Could they have upped the mains pressure?
 
Elsa TLC said:
Upping 15mm - 22mm won't help.

If your only getting 10L on the incoming then that's all you will get.

Check to see if there are any restrictions. Check all inline valves are fully open.

You do have other options!
Click to expand...
Hi, The only place i can test, the pipework has already gone down to 15mm and through many elbows and the meter. The incoming is Black Alkathene pipework with an OD of 26.9mm (just re-measured). So its old imperial stuff 3/4 Alkathene. Not copper. It immediately goes into 15mm through a brass coupling (see above pic). Then it goes through about 6 x 90 degree elbows to get to and from the meter the other side of the wall and also 2 stopcocks.

I cant test the flow at the incoming as i only have about 2 inches of the pipe coming out of the floor before it goes down to 15mm.

It seems to me while i have cut a hole in the boxing to do other work, i should upgrade it. I've asked Severn Trent to move the meter to the boundary so i can eliminate all the elbows.


PS thank to the mod for changing the title to flow. I knew that was wrong but couldn't see how to change it
 
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tommy8884 said:
Hi, The only place i can test, the pipework has already gone down to 15mm and through many elbows and the meter. The incoming is Black Alkathene pipework with an OD of 26.9mm (just re-measured). So its old imperial stuff 3/4 Alkathene. Not copper. It immediately goes into 15mm through a brass coupling (see above pic). Then it goes through about 6 x 90 degree elbows to get to and from the meter the other side of the wall and also 2 stopcocks.

I cant test the flow at the incoming as i only have about 2 inches of the pipe coming out of the floor before it goes down to 15mm.

It seems to me while i have cut a hole in the boxing to do other work, i should upgrade it. I've asked Severn Trent to move the meter to the boundary so i can eliminate all the elbows.


PS thank to the mod for changing the title to flow. I knew that was wrong but couldn't see how to change it
Click to expand...
Could you test here?
Screenshot_20240708_181403_Samsung Internet.jpg


Is this an outside wall?
 
Elsa TLC said:
Could you test here?View attachment 348374

Is this an outside wall?
Click to expand...
Hi yeah I could test but it's already reduced to 15mm there, albeit only about 1 meter from the incoming main. No it's the inside of the garage wall, just the other side of the incoming. It was all moved during our kitchen refurbishment so they could box in. Didn't have time to get it moved to the boundary. Not ideal as there are lots of 90s to achieve it. Will give it a go tomorrow
 
tommy8884 said:
Hi yeah I could test but it's already reduced to 15mm there, albeit only about 1 meter from the incoming main. No it's the inside of the garage wall, just the other side of the incoming. It was all moved during our kitchen refurbishment so they could box in. Didn't have time to get it moved to the boundary. Not ideal as there are lots of 90s to achieve it. Will give it a go tomorrow
Click to expand...
No point going from 20mm - 22mm.
It would loose pressure. In fact the internal of the 20mm black polly is more than likely 18mm.

I'd be looking more at the bends and other restrictions.

Other than that you could put a booster set in. You seem to have the room.
 
Ok. Tested at the drain down point and I'm getting about 15lpm there. So something is happening after that and before the kitchen tap it seems. Regardless in me interested in views on what fitting I need to go from the incoming main 26.9mm pipe to a 22mm copper. Now I'm in there I'm inclined to upgrade it
 
tommy8884 said:
Ok. Tested at the drain down point and I'm getting about 15lpm there. So something is happening after that and before the kitchen tap it seems. Regardless in me interested in views on what fitting I need to go from the incoming main 26.9mm pipe to a 22mm copper. Now I'm in there I'm inclined to upgrade it
Click to expand...
Imagine a fast flowing feeder river that goes into the River Thames.

What happens?

It losses it's power .
 
Elsa TLC said:
No point going from 20mm - 22mm.
It would loose pressure. In fact the internal of the 20mm black polly is more than likely 18mm.

I'd be looking more at the bends and other restrictions.

Other than that you could put a booster set in. You seem to have the room.
Click to expand...
Ta. It's not 20mm it's 26.9mm OD. The ID of the pipe is either 19.5 mm or 17.5mm (I need to take the connection off to see). The ID of 22mm copper is about 18mm, so matches quite closely no?
 
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