Water Pressure

[Danger Phoenix]

We have recently had a house done up and moved in, but we have found that the water pressure it pretty low. We have twin boilers and a 300l Megaflo system but the pressure is not adequate for 1 shower let alone 4.

We have had Thames Water come out but they claim it is the piping in the house and refuse to replace anything before the water meter as that would cost them quite a bit.

A few friends have recommended getting a mains cold water pump to go where the pipe comes up into the house, but ones with tanks look pretty expensive. Plus I am worried that these would be quite noisy.

Thoughts?

 

[Danger Phoenix]

It's illegal to pump mains cold water. Ask Thames water for their pressure reading to the property (although they will only give it to you at the pavement / street stop valve and not your main stop valve in the property). Assuming this is in excess of 3bar, you then need to check the pressure at your indoor stop valve. If theres a difference here, then the issue is in the pipework under the house / driveway / etc, which falls under your ownership. If this is old lead pipework, it might be worth the upgrade to 25/28mm pipe, but to dig up that pipework and replace won't be cheap.

Twin boilers means little here. What is the actual pressure you are receiving and what flow are you getting (measure downstairs and upstairs as both will have different readings).

Ahh, didn't realise they were illegal... had seen some boosters available online and assumed it was alright. Surely, the ones with a tank are alright?

All the pipework from the water meter outside to everything inside the house is new. I believe the builder used 22mm piping inside (where ever he could) and from the outside we have a blue plastic tube.

Thames Water have measured the water at the meter (25l/min), at the back garden (18l/min), and in the first floor bathroom (15l/m). I think they said the pressure from the mains was 2 bars.

 

[Danger Phoenix]

The person installing the megaflo for you should have checked the dynamic pressure and flow was adequate before they did so.

Django's right that you can't pump mains water directly, but you can get something like a grundfoss booster set, which is a large tank that fills up with cold water, then pumps this at 3.5 bar to the whole house. Expensive and potentially noisy, depending on installation site.

An accumulator might help, but they maintain flow when multiple outlets are running rather than increase it for any given outlet at once.

What flow rate in l/m are you getting at your outside / garden tap?

See above for flow rates

 

[Danger Phoenix]

I kind of gave up on this before but have come back to it now. The flow and pressure at the mains is 20l/min and 2 bar. Back garden it is 18l/min and 2 bar. Kitchen tap and downstairs shower output about 5l/min, and this drops to 4l/min in the first floor bathrooms and 3l/min in the loft bathroom.

If one person is showering and a tap is turned on elsewhere then the water flow and pressure drops drastically, which doesn't seem right if we are getting 20l/min coming into the house.

Getting one of those devices that pump mains water up to 12l/min isn't going to help because we already get more than that. I was looking at this, but I think that it going to actually limit the flow into the house:
http://www.stuart-turner.co.uk/products/flomate/mains-boost-extra-80/

Other options are:
http://www.anglianpumping.com/products/aps-house-booster-1000---mq
http://uk.grundfos.com/products/find-product/home-booster.html

 

[Danger Phoenix]

How do I go about figuring out what the issue is?

 

[Danger Phoenix]

If it helps, I think this is what we have (very high level):

 

[Danger Phoenix]

The water company checked the flow and pressure and said everything was good on that front. I have already tried the softener bypass and that hasn't helped. I worked out that I need a flow of 50l/min to provide water to more than one outlet at a time. I'm looking into underground water tanks (2000l) which I can pump from into the existing system.

Anyone know any decent plumbers in the Uxbridge area because our builder (who recommended what we have and installed it) has no idea why it's so rubbish.

 

[Danger Phoenix]

What type of pipe have you got coming from the street to the stopcock in the house.

A 28mm blue plastic one.

 

[Danger Phoenix]

I thought it was 28mm... most of the copper pipes are that size. Let me double check and get back to you.

 

[Danger Phoenix]

If its illegal to pump mains water how do they get away with selling these that supposedly conform to water regs?

http://www.screwfix.com/p/salamande...arch-_-SearchRec-_-Area1&_requestid=23692#_=p

You are allowed to pump up to 12l/m which is what the HomeBoost does

 

[Danger Phoenix]

Its not illegal to pump mains water totally that advice is pure rubbish, only above the 12l.

Back to basics, are you sure your stopcock is working correctly? Is it fully open? Has the builder added a secondary stop ****? Are there 15mm iso valves on the mains inline flow?

Stopcock is fully open, and there are no 15mm iso valves on the mains... as far as I can tell anyway. I will post up pictures on Wednesday (not at the property until then).

You must have a restriction in your internal pipe work going by your diagram, you are going to need to find this first before considering adding a pumped tank as you could end up with the same problem.

What showers do you have ? If they are non waterfall showers they will only need around 1bar and 10-12l/min to run well so I doubt you will need 50l/min + to run four. I can run three simultaneously with just over 30l/min and 4 bar from the mains (cylinder with pressure reducing valve to 3 bar).

A megaflow cylinder will have a pressure reducing valve on it so you are unlikely to get the pressure required to run four showers simultaneously even if you manage to increase your waterflow

All 4 showers are waterfall ones with handheld attachments. On average we may have two people showering at the same time whilst someone has a tap on somewhere... at the moment we can only have one outlet open.

 

[Danger Phoenix]

G3 certified plumber came by yesterday and he couldn't find anything wrong. 18l/min @ 2 bar coming through just past the stop ****, water softener and up to the taps.

Each tap is letting put 8l/min which is about normal. However as soon as you turn a second tap on, it drops to 4l/min out of each tap.

The plumber and other guys are discussing the issue here:
Plumbers Forum - Low Flow/Pressure Thread

 

[Danger Phoenix]

Just wondering whether you ever resolved the above problem as we seem to be having exactly the same issue now....

Unfortunately not. We've had numerous plumbers check it out and they couldn't work out what was wrong. The next step would require opening up walls and floors to look at the piping, which we never bothered to get done.

Has yours been fine previously?