Poor shower - unvented, mains pressure, sealed system

[DJBray]

Hi

A few years ago when we had central heating installed, we had excellent mains water pressure. So we had a mains pressure system installed.

However our water pressure is very unreliable (at the end of the main), and these days at best our water pressure isn't good enough to give a decent shower in one bathroom, let alone in two.

So how do we fix this? A good solution at a reasonable cost is needed.

Can we convert our existing system into an unvented system without having to replace our overspecified boiler? And is that the best solution anyway?

Can we change our system to an unvented solution and add a pump? Would that work anyway?

We're in the wilds of Cambridgeshire.

Boiler is: Thermecon system boiler 100/150 120000BTU
Hot water cylinder is: Titan unvented flowmaster

Thank you for your help!

DJ

 

[advancemaintenance1]

do you know if your water main comes in in lead? sometimes the pipe gets damaged and restricts the flow.
+you could get it replaced in alcathene from the main to the stopcock reasonably cheap ( just something to consider )

 

[gas4you]

Are you saying your cold mains pressure is awful, or just the hot water pressure?

If the latter then check the in line filter on the cylinder.

If it is your mains then I would investigate having an accumalator fitted.

I don't know much technically about these, but Simond on here has fitted loads and knows them inside out

 

[advancedplumber]

sometimes water pressure isn't always to blame and more to do with flow rates. this will have a lot to do with the size of the pipework installed. in a standard house the local water board will hook you up to a 15mm water supply, be it an old lead pipe, mdpe or copper, they are pretty much the same internal; diametre. with an unvented system it is recommened that you have a bigger incoming water main, ie. 22mm. the connection on the cylinder will be 22mm aswell and be supplied with a 22mm pressure reducing valve. i installed an unvented cylinder on time that the dwelling had 6 bar water mains pressure but after opening two outlets, the preesure fell. it had an old lead mains with a 15mm (approx) internal diamtre. i people where ment to have the lead pipe replaced but then due to money shortages in the building project they never done it.

 

[DJBray]

Hi, thanks for your comments.

We are right at the end of the mains. Its 1 inch plastic pipe for about 200 meters/yards as it comes to our house. Before that its old & fragile 4"? asbestos.

As I learn more I think the issue is both flow and pressure coming from the mains.

Inside the house we have 22mm pipework going into and out of the hot water tank stepping down to 15mm for the last couple of metres in the bathroom. The cold is also 22mm until it T's off to go into the hot tank and then its 15mm the last couple of metres.

We have one short length of pipe (1 inch long) as the 1 inch plastic mains comes into the house where it goes to 15mm copper before stepping up to 22mm. Could this be having an impact on the flow even for such a short length? We are planning to have this restriction removed anyway!

The mains pressure itself is very variable, depending on whether the asbestos pipe is leaking badly or just with small leaks. (Depending on when the tractors go over the pipe as often as not.)

Anglia water this week offered to replace the asbestos pipe by inserting narrower 30mm plastic pipe inside the old asbestos pipe. We expressed concern that this would reduce the flow further even though it would fix the variable pressure problems. Anglia water very kindly said next time the pipe breaks they could put the smaller pipe overground so we could assess the impact before they took any further action.

Its a bit of a continual nightmare.

Thanks for your advice.

DJ