Replacing mains pipe to increase working pressure and flow?

[darranh]

Hi.
I am wondering whether it is worth replacing my mains pipework. Unsure if it is lead however have quite poor flow and working pressure which supplies a green star 36i combi boiler.

The water meter in street run about 15m underground to stop tap in kitchen back of house. Before that there is a tap in the garage at about 5m from water meter. The tap in the garage flows 18l/min and the stop tap in kitchen 10m on flows 14l a minute.

The static pressure is 2bar and working pressure to boiler hot water is 1 bar measured by Worcester engineer. It needs 1.6bar to work to max level.

I believe the underground pipe is 15mm lead or copper, would replacing as much as possible with 25 or 30mm actually improve the working pressure or flow once its connected to the 15mm pipe work around the house.

A quote to replace underground pipe to 7m from water meter (rest would mean digging up kitchen) with 25 or 30mm and make good the trench was given as £780.

Obviously I don't want to waste money on bigger pipes if it means nothing from a functional point of view, Id put that money towards a different solution. The United Utilities man didn't feel it would be worth it as he said pressure would stay the same, although he clarified he was talking about static pressure as that's all they measure.

Any advice much appreciated.

 

[Agile]

Your appliances work on dynamic flow rates. See the FAQ to explain.

I would suggest you need a flow rate of 14 li/min @ 1.0 bar to gain the maximum use of your boiler!

If you are paying others to do the upgrade I doubt its work it but if you can do the digging then the cost will come down much lower.

But water pipes need to be 750 mm below the surface.

Tony

 

[ree]

Run new supply in 25mm MDPE from the external stop-tap to the internal stop-tap. You run in 25mm all the single length way. Locate the internal stop-tap wherever its accessible and convenient for you.

Or, are you saying that there is no external stop-tap after the water meter in the pavement/street?

What does "rest means digging up the kitchen" mean?

Look at "Similar Topics" at the bottom of this page.

 

[darranh]

Sorry, I mean the kitchen with the new boiler has just been refitted. The stop tap is under the newly fitted kitchen sink.

The engineer mentioned instead fitting to kitchen which would mean digging up kitchen floor, running from external stop tap 7m to back of garage with 25mm MDPE fitting internal stop tap there and then plumbing in from that point, going up and over kitchen ceiling by accessing under floorboards upstairs then back down far wall where boiler is.

My concern is that creates even more length of pipe rather than less, and so not improve the problem.

 

[simond]

Static pressure would the same if you put a 100mm water pipe in.

So United Utilities werent being very helpful.

They should provide you with an estimate of flow rate or use one of their adaptors on the water meter that allows them to measure flow rate at that point. When you know what is available in litres/min in the street, you will get a similar performance indoors with a wider bore new pipe.