Upgrading mains supply - will it make any difference?

[lazlo]

Hi All,

I'm looking into ways of increasing the supply flow rate, so that my shower doesn't reduce to a trickle when other outlets are used at the same time.

The mains supply is in 15mm (what I can see of it anyway). My question is - will getting the provider to upgrade this to a bigger pipe actually make any difference, given that the pipework downstream of the stopcock is 15mm too? It seems to me that it wouldn't help, but I don't know enough about how these things work to decide.

It's a combi boiler system (Alpha Flowsmart).

The other solutions I've seen are a water accumulator or breaker tank + pump, though I'd prefer to save the space if possible.

Many thanks in advance and apologies if this has been asked before.

 

[Riley]

A combi boiler can only produce xx litres of hot water per minute. If you open another outlet then this will split the supply between the two. An increased mains may improve it slightly but if the combi is already working to full potential then it can do no better. Whoever installed the boiler should've checked water pressure and flow. If you want to use two outlets at the same time then you might be better off looking at an unvented cylinder. In the first instance though get a plumber out to test the flow and pressure so you know where you are to start with

 

[lazlo]

Thanks for your reply.

The combi is not working to full potential, that's the issue. It's supposedly able to deliver 18l/minute of hot water.

Whereas the total mains flow rate is only 12l/minute (measured by myself with a bucket and stopwatch). Pressure is 2.0 bar.

And shower slows even if a cold tap is opened.

 

[Plumbstar Tom]

i agree with the above, combis are great if its explained what their limitations are

you could look at a decent electric shower, flow rates from the bigger ones are pretty good but need 10mm cabling

 

[Riley]

How old is the boiler?
How did you measure the pressure?
Did you measure static and dynamic pressure?

 

[lazlo]

The boiler is 4 years old (I tried to post a link to the brochure / specs for it, but I'm not allowed).

I only measured static pressure, with a gauge like this:


thanks!

 

[Stanios]

12l/m is just wrong regardless of what your boiler is doing. You want at least 20l/m and upsizing your main is the best way to do that. Try independent companies rather than your water company (much cheaper)

 

[plumben]

The boiler is 4 years old (I tried to post a link to the brochure / specs for it, but I'm not allowed).

I only measured static pressure, with a gauge like this:
View attachment 23119

thanks!

Re attach that gauge to the mains, record the static pressure then open up one outlet record the pressure then open another outlet so theres two open and record the pressure

 

[Riley]

12l/m is just wrong regardless of what your boiler is doing. You want at least 20l/m and upsizing your main is the best way to do that. Try independent companies rather than your water company (much cheaper)

I may be wrong so apologies but isn't 12 lpm the minimum your supplier is obliged to provide? That's why these mains booster pumps cannot boost to more than 12l???? Might be worth speaking to your supplier about what to expect in your area

 

[lazlo]

Ok, I just measured it again.

The static was 2.2 bar, and it didn't really drop much at all with the outlets open: 2.1 bar at 12l/m.

thanks!

 

[Riley]

I'd still speak with your supplier and see what they say. They can guide you as to wether a mains upgrade will help

 

[lazlo]

Thanks Riley, will do.

 

[Stanios]

I may be wrong so apologies but isn't 12 lpm the minimum your supplier is obliged to provide? That's why these mains booster pumps cannot boost to more than 12l???? Might be worth speaking to your supplier about what to expect in your area

Not sure if theres a minimum they are obliged to supply but 12l/m is what water regs allow you to pump from mains so pump manufacturers have to comply with that.

Also worth checking if pressure/flow fluctuates during peak and offpeak this would suggest your whole area has bad mains

 

[Riley]

Only say that as we don't know your specific circumstances. You could be rural for example and the mains supply to you is just generally poor

 

[Riley]

Not sure if theres a minimum they are obliged to supply but 12l/m is what water regs allow you to pump from mains so pump manufacturers have to comply with that.

Also worth checking if pressure/flow fluctuates during peak and offpeak this would suggest your whole area has bad mains

Good shout on various times

 

[lazlo]

I'm pretty much the exact opposite of rural! London N1.

I've also read that if it's under 12 l/m they're obliged to do something about it as you mention, but it does meet that minimum here, just.

 

[goz666]

12 L/min to the boundary they are obliged to provide. If it drops at the outlet it's not their problem.