Head scratching moment.

[Starky]

Hi all,

On my current job (plumbing ,CH/HW) for a loft conversion on a first floor maisonette. I was planning on adding a water accumalator to improve pressure and flow rate. which is looking like a no go due to cost.

I think the route we are going to take is to increase the water main size from the external stopcock. We currently dont know what the size of the water main is. The main comes into the property at the Bottom of the stairs by the front door in 15mm copper then goes around the flat in 15mm.

What I'm struggling to work out is how to calculate what improvement we can add to the flow rate. I appreciate we need to establish the incoming main size which we will be doing. Currently there is 2.4 bar static pressure 0.8 dynamic pressure and 12lm flow rate at the kitchen sink.

There is approximately 5m from the external stopcock to the internal stopcock, it then rises into the loft approximately 5m again, then across 7m to drop down into the kitchen.

I would appreciate any help on calculating what difference would be made by increasing the water main size and changing the internal 15mm to 22mm.

But what I'm really after is a table or book so I can also work it out for my self in the future. I've spent countless hours online trying to find a idiots guide for the calculation/table but have had no luck.

Thanks.

 

[Dilalio]

Have you asked the provider to measure what they are supplying to the main stopcock? That would be a starting point.

 

[ShaunCorbs]

I would phone the water board up and see what your getting in the road

 

[Starky]

Hi Dilalio,

A little about my self, just so I don't seem like a complete wally. I trained as a plumber but quickly moved on to gas. For the past 10 years I've been solely working for a company, working on social housing. My main work is boiler break downs. But I'm in the process of going self employed. Hence the plumbing questions as I'm having to get back into it.

No I haven't yet. I will get on to that. Would you know where I can find the formula so once I do have the incoming pressure at the main stopcock/ flow rate I can then do the required calculation.

Thanks.

 

[steadyon]

Have a look at http://yorkshirecopper.com/wp-content/uploads/Technical-Guide-full-issue-02_14_Really2.pdf particularly section 4.2 which has the Nomograms for cold and hot water pipe sizing.

 

[Starky]

Steadyon,

Thank you I'll have a peak at it once I've finished the install I'm on. Much appreciated.

 

[Dilalio]

There are also apps you can get - I have them and they're useful now and again.

The street dynamic and pressure is your first point of call though, as I said.

Also, don't forget to take the periods of high demand into consideration before you go quoting figures to the homeowner

 

[Starky]

Steadyon I've looked at the nonograms and it's starting to make sense ( add up total meterage of pipe add fittings then follow the graph to calculate losses... I hope lol.) thank you for the link.

Dilalio, I'm going to get in touch with the water board and then make my calculations. Could you let me know what apps you use please?

As you say I need to take into account periods of high demand, for example In the morning there will be more demand on the main as people get ready for work? And how do I add this to my calculation?

 

[Starky]

Right I've had the water board out who have tested the main in the street. There is 50l/m flow rate and static pressure of 2.3 bar. This was at 12 o'clock so not peak demand.

I've had a look at the nomograms in the link above, I would like to give the customer a idea of what will be coming out the taps
But can't get my head around how much flow rate and pressure I'll lose.

From experience I would run 25mm MDPE up to the property (6m) then run the main in 22mm upto the loft (5m) then run across (7m) then branch of in 15mm to the taps and boiler. I would hope this would be enough to provide me with about 17 to 18l/m flow rate. But I want to see it on paper and be able to calculate it for my self in the future. Can any one help.

 

[Dilalio]

This is good info but will likely give you some more head scratching

Domestic water-supply - example

 

[Starky]

Thanks.

I've already read that one and although very good, there has been a lot more head scratching.

 

[Dilalio]

The key is to start with the flow required at each outlet and work backwards from there to establish flow rates viable with the supplied head.

 

[Starky]

Thanks mate, I think I need to sit down with someone and go through it.

 

[Dilalio]

Here's a good resource...

The 2 PDFs about installation tips (pipe sizing) are quite well written (about half way down the list)

Installation Tips | Initiative copper

 

[Dilalio]

These ones...

http://copperplumbing.org.uk/sites/...ttachments/pipe-sizing-basic-principles_1.pdf

http://copperplumbing.org.uk/sites/...tachments/pipe-sizing-tabulation-method_1.pdf

 

[Starky]

Thank you very much pal. I'll take a peak once I've put the nippers to bed.