Cold Water Accumulator or upgrade water supply

[MD10]

Bit of a back story; I am planning an extension to my property and adding in a couple of showers. Currently have a combi boiler; and the usual story of not being able to open a tap while someone is in the shower due to pressure. I want to be able to run 2 showers at the same time without losing pressure.

I have had a couple of plumbers out to quote for an unvented tank and new boiler however they have both mentioned my mains pressure is not that great. (from what the plumber said it is a "3/4" black pipe in to the ho)

Plumber number 1: suggested to upgrade the mains supply to the house to a 25mm and he will upgrade the 15mm pipe to my currently boiler to a 22mm pipe. Boilber will stay in the same location

Plumber number 2: Unvented system with boiler and cold water accumulator tank (Pressurised). His opinion is that if we upgrade the mains to the house the pressure isnt going to increase that much. Boiler and 2 tanks to be moved to the garage.

I really do not want to put a noisy pump in; so these are my 2 options. Does anyone have any opinions on this? what might be the better option(likely to work best)? Is it worth me digging my half my drive to run a new 25mm pipe?

Side note: I have 2 feeds coming into the house (1 to the downstairs cloak room and the other in the kitchen which supplies the rest of the house). The only thing I dont know if these are split along the pipe (T'd off) or 2 separate pipes have been run from the main road.

Pressure on the outside tap was about 2.2 bar and inside tap was about 16 litres per minute

Sorry for the long essay. Just a bit confused as I know nothing about plumbing.

 

[muggles]

Was the 2.2 bar measured with a tap turned on, or is that static head (no taps on)? What's the pressure with the kitchen tap running at 16l/min?

You don't necessarily need a new boiler... your existing one may well be fine, and you can just add a cylinder to the system

 

[MD10]

Was the 2.2 bar measured with a tap turned on, or is that static head (no taps on)? What's the pressure with the kitchen tap running at 16l/min?

You don't necessarily need a new boiler... your existing one may well be fine, and you can just add a cylinder to the system

Outside tap was measure with both kitchen tap on and off. Both gave a similar reading around 2.2 bar.

I currently have a combi boiler, both plumbers I spoke to said they wouldnt recommend keeping the combi with unvented system.

 

[TicTac]

As long as the combi has enough spare capacity to supply the unvented cylinder, then you just need to add a circuit and a valve to it. The hot water side of the combi can continue to feed the kitchen, and the showers will get plumbed in from the cylinder. Sounds as though you need a more experienced installer.

You can mole the drive so that nothings dug up, and maybe go for a 32mm pipe rather than 25 though, then you can decide if the pressures sufficient for a cylinder rather than a pumped system. Keep an eye out for one of the Clancy Docwra vans, and have a quiet chat with them.

 

[muggles]

As above, no reason to change the combi unless it's getting old and unreliable.

If you have 2.2 static and little change at 16l/min, I'd suggest your existing mains supply is fine. Would be good to know what flow rate you get with 1.5 bar remaining (IE turn more taps on until the pressure drops to 1.5, measure and add up the flow rates from each tap)

 

[MD10]

@TicTac I just reached out to a couple of companies to get a trenchless install. So lets see what price they come in at. I am in the east midlands, I dont think i have ever seen a Clancy Docwra van before.

@muggles, it was the plumber that did all the testing. I dont have the tool to test the pressure. What are you looking for in the flowrate at 1.5 bar, so if i get a chance for someone to test it for me i know?

The boiler is pushing on 12-14 years old but its not giving too many issues.

Thanks both for your comments. Maybe i'll reach out to a third plumber.