Can you identify my mains water pipe

[nishnish]

Hi,
A black plastic water pipe about 20-21mm OD supplies my house.
Is that alkathene?
Here's the stop top which joins it to 15mm copper:

Untitled

• nishnish
• 28 Dec 2010
• 1

Untitled

• nishnish
• 28 Dec 2010
• 1

Untitled

• nishnish
• 28 Dec 2010
• 1

You can see one side of the stop tap has a British kite mark and with "31" written above it. On the other side has "1/2" meaning half inch of some description?
Does that mean 1/2" ID pipe? I can't see any other way 20-21mm OD can correlate with a half inch.
Any help would be appreciated.

This then goes down to 15mm copper which supplies the entire house.
Hot water from the boiler dies away when any cold tap is turned on. I'd like to hopefully improve that.
I want to replace the other side with something else; 25mm MDPE?
What adapter or stop tap would I need to get to connect this black pipe to 25mm MDPE?
Thanks.

 

[Bahco]

If your boiler is a combi, upgrading your supply wont help the hot water flow!

Leave alone.

 

[nishnish]

If your boiler is a combi, upgrading your supply wont help the hot water flow!

Leave alone.

Yeah it's a combo.
I realise that my WB 240 RSF restricts DHW flow to 8L/min.
DHW flow is fine normally, except when a cold tap is turned on. Then I think the combo is being starved of flow, due to:

1. The whole system being supplied by a single 15mm.

2. The Combi being the very last device on the cold pipe.

As you saying that addressing this will not improve matters?

 

[nishnish]

Any ideas what the incoming pipe is?

 

[seco services]

would say alkathene.
1/2" ID is inside diameter.

 

[nishnish]

would say alkathene.
1/2" ID is inside diameter.

Thank you.
I may at some point replace the incoming pipe with 25 or 32mm MDPE.
Until that time, I do want all of the flow coming into the house to be available, rather than hitting a single 15mm.
The total pipework from there is a 10m horizontal run of 15mm, thru the cellar, then at the end it splits into various small runs:

1. 2m to gnd flr washing machine.
2. 4m to gnd flr kitchen sink. After 2m this splits off to gnd flr combi, which is a further 4m away.
3. 3m to 1st flr bathroom with toilet, sink & simple shower mixer bath tap.

At some point I would like a bathroom on the top floor (2nd).
I'm concerned with:

1. Keeping the flow to the combi up to it's 8L/min flow limiter. It can't manage this currently, when any other cold water device is used.

2. When the 2nd bathroom comes online I'd expect further flow issues which I'd like to get sorted now, as I'm addressing the DHW issue.

Any recommendations on what pipe I should use for the 10m run?
I was thinking 25mm MDPE for that, a tee off 6m along of 22mm hep2o up to 2nd floor (6m vertically about 12m in total) then taking all remaining tees, to the above devices, individually, off the MDPE.
How's that sound?
22mm hep2o and fittings are considerably cheaper than 25mm MDPE, but should I stick with MDPE for flow, or is it just overkill?
Currently pressure is 3.5bar.
Thanks for any advice.

 

[hi1]

Has the flow from this boiler ever been acceptable? I'm thinking there may be a flow restrictor/regulator fitted in the domestic hot water side as there is on my wb 24i. This can wear out and mess up the flow rate. Alternatively wb seem fond of putting gauze filters in the water inlet, this may also be blocked or restricted.

 

[doitall]

1/2" ALKATHENE.

On the pipe will be blue writing (Class C) or green writing (Class D) it's important you get the insert to match.