How do I enhance my mains pressure?

[camngnp223]

Hi everyone!

I have a question that I'm sure can easily be answered by many of you. Here's the necessary background:

We have recently fitted a new kitchen, including a new kitchen tap/mixer (which has fairly narrow feed tails). The pressure in the property was not good (because of a very low header tank), so a shower pump was fitted. Because of the pump, the flow of hot water out of the kitchen tap/mixer is just fine. However, the cold flow (which is sourced directly from the mains) is very poor.

Now the question:
How can I improve the pressure/flow from the cold mains?

These are solutions I'd like to avoid:
(1) Replacing the existing 15mm feeds with 22mm pipes.
(2) Replacing the tap/mixer with another with wider feed tails.

This is a potential solution I'd love to have some advice on:
(1) Installing a accumulation/expansion/pressure tank directly beneath the kitchen sink. Could this work to increase pressure at all?

Anyway, I'd be very grateful for any thoughts you might have.

Huge thanks,

Cam

 

[AlanE]

And the actual mains pressure is? measured at say your mains fed outside tap.

 

[camngnp223]

And the actual mains pressure is? measured at say your mains fed outside tap.

The mains pressure is 1.1 bar. Thanks!

 

[giblets]

Is that the working or standing pressure?

Also when you open the cold tap on the sink does the flow rate gradually taper off?

 

[camngnp223]

Is that the working or standing pressure?

That's static pressure. Thanks!

 

[Agile]

This is a potential solution I'd love to have some advice on:
(1) Installing a accumulation/expansion/pressure tank directly beneath the kitchen sink. Could this work to increase pressure at all?

Anyway, I'd be very grateful for any thoughts you might have.

Huge thanks,

Cam

Accumulator, cue Simond !

For an accumulator to have much output it needs to be quite large.

You only get a fraction of the total volume as useful enhanced flow. So a 200 litre accumulator might give 60-100 litres of improved flow. It would not fit under a sink though.

Next problem, I think that most accumulators are designed for bathroom water rather that potable water to feed a mains tap. Simmond can advise on that too. I expect there are stainless steel accumulators designed for potable water but I have never seen large ones.

There is a large Grunfoss unit which stores potable water and pumps it at pressure to the house. They are very good but cost about £1000 and take up about the space of an extra tall washing machine.

Tony

 

[muggles]

It might be possible to get a pump fitted to your incoming mains, but you'll need permission from the water authority to do this.

 

[Agile]

Cam,

the flow limitation is usually the size and material of the supply pipe from the street.

The correct engineering solution is to overcome the problem by replacing the incoming pipe in blue poly.

Usually costs about £600-£1200. Outside property has to be done by water supplier contractor. Has to be buried 750 mm + down in the garden.

Tony

 

[camngnp223]

Cam,

The correct engineering solution is to overcome the problem by replacing the incoming pipe in blue poly.

Tony

I would like to avoid having to replace the incoming feeds (especially from the street mains).

Could someone advise on the possible benefits of an accumulation/expansion/pressure vessel (with an associated pressure charging pump, if necessary)?

Again, huge thanks,

Cam

 

[Agile]

All of those have a limited amount of additional flow.

A new supply has 24/7 increased flow rate.

Wheres Simond?

Tony

 

[simond]

Here I am, on my horse (beat you to it, ChrisR). Well, a tractor actually....

With 1.1bar static pressure an accumulator on its own is not going to do as much as one would like, and will not match the force of the pumped system you have on the hot side.

That is the first problem, the second is that there will not be sufficient space under a sink to site an accumulator larger than about 120 litres (60 litres usable).

3rd problem is that accumulators are expensive (if you buy the ones covered under the UK patent)

On a plus point, the accumulator can carry potable water and is approved.

If you really wanted this sorted you could fit a pumped accumulator, these can be connected to the mains. This is a better solution than a Grundfos homebooster but slightly more expensive.

But I have to say, whilst it makes sense spending well over a grand for unvented systems and large combis, I can't really see the cost justification for a kitchen sink tap.

 

[Mike2007]

A new MDPE supply is the only answer I would think. The overnight change to your outlets would more amazing than you think?
I did one for a customer and had to a fit PRV because there was then too much pressure!

 

[simond]

Not sure what you mean, Mike2007.

Replacement of the main for an MDPE one will not increase static pressure at all, it may increase flow rate. But because the static pressure is low it suggests that the local water network is not well specced and the chances of a significant improvement in water flow are reduced.

If you mean that you fitted an accumulator and the raised overnight pressure allowed a sensible 'peak' water charge, then I understand. But before recommending this, one would have to ascertain whether the static incoming water pressure did rise off peak in the OP's situation.

Finally, were this the case, the accumulator would not work very well during daytime mode because the set air pressure would be too high for a useful amount of water to be stored at the lower mains pressure.

 

[Agile]

Like so many of these postings, there is insufficient information on which to make any meaningful recommendation.

What would be needed is a static and a dynamic water supply pressure, details of the supply pipe ( material, length and routing ).

What is certain is that the OPs expectation of a cheap solution which would fit under the sink in not a posibility.

Tony

 

[ChrisR]

A cheap solution may be perfectly possible.
You might just have some dirt in your tap.
You might find isolation valve(s) partly closed.
You might have an inappropriate tap.

What's the flow, at the kitchen cold tap, all other outlets off, in litres per minute?
Now open the garden tap fully as well, tell us what both flows are.
Standard domestic bucket is usually 9 litres, if that helps.

For a kitchen tap you probably want flow, rather than pressure, as a priority. For a garden hose though you need both.

If you do consider an accumulator, don't take any notice of patents. There's no paternt stopping you putting an ordinary accumulator on the mains. Cowboys get patents on really obscure applications, then cowboy salesmen who ought to stick to playng with tractors like to get you worried so they can flog you something expensive.