Low pressure in Kitchen Hot Water Tap; Solution=Shower pump?

[Steady]

I see you correctly identified the true reason why the flow from the hot tap in the kitchen was so poor- i.e. small bore flexi hose supplying it .And conversely why the bath hot tap was okay (full bore pipe) .

Yet despite this you go to the expense and trouble of fitting a booster pump to the kitchen tap when all it needed was full bore pipework supplying it. All you have done is increase the pressure at the tap. This is not the same as flow rate which is what the problem was all about in the first place. The flow rate i.e. litres per minute will be virtually the same as before. I think you have confused the two issues and wasted a fair amount of money in the process.

 

[sunama]

I see you correctly identified the true reason why the flow from the hot tap in the kitchen was so poor- i.e. small bore flexi hose supplying it .And conversely why the bath hot tap was okay (full bore pipe) .

Yet despite this you go to the expense and trouble of fitting a booster pump to the kitchen tap when all it needed was full bore pipework supplying it. All you have done is increase the pressure at the tap. This is not the same as flow rate which is what the problem was all about in the first place. The flow rate i.e. litres per minute will be virtually the same as before. I think you have confused the two issues and wasted a fair amount of money in the process.

Here are the facts:
Flow rate without pump: 1.5litres/minute
Flow rate with pump : 8 litres/minute.

With regards to pressure: now that the pump has been fitted, the pressure through the tap is immense, such that when the spray function is on, at full throttle water sprays all over the kitchen. Before the fitting of the pump, the spray was very weak.

Adding the pump was a 100% success as it solved the problem.

Replacing the hoses with a larger bore variety was not an option as they would simply not fit through the monobloc of the tap fitting. This is why the manufacturer chose to use narrow hoses, in the first place.

The only other way around this would have been to buy a different tap, similar design, but with wider flexi hoses (ie. low pressure design). In general, I found these low pressure taps to be very expensive and the range limited. By using the pump, I am able to select and use virtually any tap that I choose to, as I have the high pressure available to me, should I need it.

 

[Steady]

Ok.It seems more logical now but it is nonetheless very unusual to see booster pumps fitted to domestic hot water supplies unless it's for showering. Most consumers would normally look at the tap as the area for improvement but I guess you had your reasons for not changing it. Hope the pump idea proves reliable for you in the long term.

 

[ChrisR]

If you put the pump at the cylinder end without a "flange" of some sort it would probably suck air down the vent.
You could put your pump back on ebay and get what I'm surprised nobody recommended in the first place, a 1.5bar version!

 

[sunama]

If you put the pump at the cylinder end without a "flange" of some sort it would probably suck air down the vent.
You could put your pump back on ebay and get what I'm surprised nobody recommended in the first place, a 1.5bar version!

Im surprised people are still making recommendations given that I have succeeded in solving the original problem. But this is good as it will allow someone else having a similar problem as me to use this thread as a reference.

First off, the Stuart Turner 2.3 Bar Monsoon Extra Negative pump that I am using has solved the problem 100%. I am a perfectionist, hence, I dont want anyone to take that statement lightly. I bought this pump for £126 inc del. The cheapest online price was £308 inc del. The cheaper Stuart Turner negative pump wouldve still have cost more than the £126 that I paid. Even the (lower quality) Salamander pump wouldve cost more than what I paid. Buying a lesser pump wouldve given me less flow and pressure.

The installation of a 1.5Bar pump, installed directly at the cylinder would have required more extensive work (for which a plumber wouldve been required) and would have given me less pressure than I am currently getting through the tap with the existing pump. Moreover, by buying a 2.3Bar pump, I have future proofed my kitchen hot water tap. In the future I intend to buy one of those swanky, looped, 40cm-high spray taps that are usually found in commercial kitchens. These taps generally require as high a pressure as possible. 1.5Bar would be the minimum. Some even specify a minimum of 3.0Bar! Given this, if I were to replace the existing pump, I would do so, with an even more powerful pump.

In summary, my current solution has allowed me to:
- get a powerful pump which is adequate for the purpose I require it for;
- install the pump without interfering with the plumbing of the pipework of the rest of the house;
- install the pump simply, without having to pay a plumber to install the pump near the cylinder, thus saving money; and
- future proof the kitchen hot water supply to allow me to use taps that require high water pressure;

The one (minor) negative point about the pump is that it is a lot larger than I wouldve liked. But as the pump is hidden away under the sink, its not too much of a problem. Anyone buying this pump should consider the size (and the noise).

 

[sunama]

Most consumers would normally look at the tap as the area for improvement but I guess you had your reasons for not changing it. Hope the pump idea proves reliable for you in the long term.

I totally agree with this. However, the main reason for the abolve solution would be cost - its far cheaper to buy a low pressure tap than a big powerful pump, just to deal with a single tap. However, my solution was a guarenteed method of solving the problem. Buying a low pressure tap would not have had guarenteed results - I wouldve had better flow, but not the super high pressure and flow, that I have now.

 

[IKM]

I read this thread recently (Dec 2011) when researching solutions to low hot water pressure in the kitchen. I have now fitted a Grundfos UPA15-90 Water Pressure Home Booster Pump in the hot pipe under the kitchen sink. This has increased the hot water flow from the monobloc mixer tap from 4.4 litres per minute to 7.2 litres per minute. The increase in flow is not dramatic but it is now enough and this pump has the advantage of being compact, easy to fit, quick to turn on and virtually silent in operation. Cost was total £135.54 including shipping from Discounted Heating Ltd.

The cold water is fed from the mains at about 6-7 bar pressure. Using the service valve in the cold pipe I have reduced to flow to match the hot flow. Any increase above about 8 litres per minute results in unacceptable splashing in the sink.

For reference the hot water in my house is a conventional vented system with the cold storage tank in the loft, the hot storage cylinder on the first floor and the kitchen on the ground floor. There is about 5.5 metres head between the surface of the water in the cold storage tank and the outlet of the kitchen tap. Piping is 22mm copper as far as the bath on the first floor then 15mm to the kitchen.

I hope this helps someone in the future.

 

[Bazilbrush]

This has been a helpful set of comments to read, but I have a slightly different problem.
We are off grid for water and collect ALL ours from rain. This is pumped from an underground tank to a tank in the loft via a UV filter. The tank feeds the house via three 28mm pipes: one to hot tank, one to cold ground floor and the third to upstairs cold feed. We drop down to the relevant pipe sizes when we come to the bathrooms, kitchen etc.

Here is my problem. Rain water is slightly acidic Ph of 6.4 in our case. This is great for bathing/showering clothes washing etc as it is naturally antibacterial but very bad for drinking. The body needs to be alkaline and so we have to raise the Ph level at the kitchen sink for drinking.

The pressure we have available is 0.5bar Re-mineralising filter has a 6mm bore pipe. The drinking water trickles (0.3ltr per min) I want to increase this to 1.5ltr per min (can't go much faster than that or the re-mineralising effect will be reduced). I am looking for a gentle pump to put just on the water inlet to the filter, one that won't pop the John Guest joints off, not be noisy or too expensive. Can anyone suggest a solution?