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R

rallen

Hello, our water pressure is quite low here and the water board have not really done anything about it in 10+ years now. To make matters worse I have a water softener which is not very large and it is causing a pressure drop on an already low pressure system. I was thinking of installing a water pump to help with the pressure. I have been to places in Europe where tall buildings or houses on a hill use their own water pumps to help carry the water to the top floors, so that is where I got the idea from.

I know however that here in the UK there are, or must be, regulations regarding fouling the water supply with dirty water and although I do not think a water pump in my house would foul the water supply, it may "suck" dirty water from neighbours's hopuses if the mains pressure is very low, or if there is a supply interruption somewhere. Just thinking aloud here, what are your opinions?

Thanks
 
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Yes. A 60m mains in 15mm copper or old lead will drop a LOT of pressure when you open just one tap.

Pressure loss is proportional to the distance the fluid/gas has to run and also inversely proportional to the diameter of the pipe. The 60m mains is your problem here. Upgrade it to 25mm mdpe or even 32mm mdpe (the price difference will be quite small) and you will see a large jump in the output of your taps etc. As you do renovations over time you can re-plumb the internal pipework to take even more advantage of it should you wish.

This is the reason why most unvented cylinder manufacturers state that the incoming cold supply has to be in 22mm pipework so that the flow rate with multiple outlets opened is sustained.

I would guess that your bathroom taps are high pressure taps so the flow rate through them at 1 bar (probably less by the time the water reaches them) is going to be fairly low. as 1 bar is usually the minimum recommended pressure for high pressure taps.

If your existing mains is lead the water company may well do a free lead mains replacement program, some of them do.

Have a look at the pipe entering the stopcock. If it's 15mm copper on a 60m mains run then that is your problem.
 
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Just done the calculations for you and here are the results based on the following water velocities through the mains. I've assumed you have a 20mm MDPE pipe (internal diameter approximately 16mm).

Your flow rate at the kitchen tap (presumed) is around 15 litres per minute. That's a flow velocity of 1.24m/s. That equates to a pressure drop of 1.63 bars at that flow rate, not far off what you are getting. That flow rate is for new pipe and assumes no fittings/restrictions which will of course drop the pressure further.

In the same example, upgrading to 25mm MDPE pipe (bore of 20mm roughly) will drop the flow velocity to 0.8m/s. The pressure drop is now 0.54 bars at the same flow rate. 32mm MDPE pipe (which I recommend you fit due to your water mains length) will drop the flow velocity to 0.47m/s and the pressure drop to a tiny 0.15 bars.

Answer - fit 32mm MDPE pipe and that should sort out the pressure drop, at least in to your house.

The poor flow rates at the bathroom tap are (I would guess) down to them being high pressure taps? I would be surprised if you even get 1 bar of dynamic pressure at the furthest outlets in your house so high pressure taps will be too restrictive at the moment.
 
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But he will still need to pay for the up-graded connection to the water undertakers main between the road main & their boundary stop valve, won't they ? How much are they charging for this nowadays ? (use to be the same cost for 20,25 & 32mm with Thames)
 
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The 15lt/min was measured at an outside tap, at very low level, and very close to the mains. The kitchen tap is a more modern and more restrictive than the simple outside tap.

The mains in is 20mm plastic with 16mm internal. All bathroom taps are european so I suspect yes they are made for mains pressures, not water storage tanks.

I am now considering the "mole" system that someone else mentioned to run thicker water pipes from the water meter to my house, but there is the old pipes and telephone and electricity buried there somewhere and I am afraid in case we severe any of these. Has anyone here got experience with this kind of work?
 
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chris watkins said:
But he will still need to pay for the up-graded connection to the water undertakers main between the road main & their boundary stop valve, won't they ? How much are they charging for this nowadays ? (use to be the same cost for 20,25 & 32mm with Thames)
Click to expand...

Depends on the water company. Anglian water where we live are doing them for free for my customers.
 
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rallen said:
The 15lt/min was measured at an outside tap, at very low level, and very close to the mains. The kitchen tap is a more modern and more restrictive than the simple outside tap.

The mains in is 20mm plastic with 16mm internal. All bathroom taps are european so I suspect yes they are made for mains pressures, not water storage tanks.

I am now considering the "mole" system that someone else mentioned to run thicker water pipes from the water meter to my house, but there is the old pipes and telephone and electricity buried there somewhere and I am afraid in case we severe any of these. Has anyone here got experience with this kind of work?
Click to expand...

My guess was spot on then when I assumed 20mm MDPE. The calculations are pretty accurate then.

I've no experience of moling companies myself. I normally just hire a digger for the time I need it and do it that way tbh. Probably a 2 day job with a digger if there is nothing in the way but earth to move.
 
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Yes your calcs make sense - I have 3 bar which drops significantly as I open the taps. With 1 tap open near the mains, the pressure then drops to 1bar which is too low at the other end of the house for the bathrooms.

I do not fancy digging up my drive to pass new pipe because it sounds like a lot of work and great expense. Plus there is water supply in the detached garage - there must be a split somewhere under ground just to complicate things.

How does the Stuart Turner pump work? How does it implement this limit of 12lt/min ? Does that mean that if I have say 15 lt/min on my outside tap and then install the Stuart Turner , I will see the 15 lt/min to drop to 12 lt/min ???
 
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rallen said:
How does the Stuart Turner pump work? How does it implement this limit of 12lt/min ? Does that mean that if I have say 15 lt/min on my outside tap and then install the Stuart Turner , I will see the 15 lt/min to drop to 12 lt/min ???
Click to expand...

They detect the through flowrate. If it is above 12 litres per minute they simply don't activate. If less than 12, they will cut in with a variable speed pump until 12 litres is reached.
 
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rallen said:
Yes your calcs make sense - I have 3 bar which drops significantly as I open the taps. With 1 tap open near the mains, the pressure then drops to 1bar which is too low at the other end of the house for the bathrooms.

I do not fancy digging up my drive to pass new pipe because it sounds like a lot of work and great expense. Plus there is water supply in the detached garage - there must be a split somewhere under ground just to complicate things.

How does the Stuart Turner pump work? How does it implement this limit of 12lt/min ? Does that mean that if I have say 15 lt/min on my outside tap and then install the Stuart Turner , I will see the 15 lt/min to drop to 12 lt/min ???
Click to expand...


Have a read of this: Are you feeling the pressure? - Modern Building Services
Haven't used an accumulator on any jobs but the principle is good (depending on how much water you're using obviously!). If you're finding fittings closer to the mains connection are robbing flow from more distant taps you could consider fitting flow restrictors to the closer ones, but as people have said the water board only promise minimal flow/pressure and if you want more you'd have to look at a break tank and pump.
 
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A simple break tank and pump we fitted about 5 years ago - no comebacks

home booster2 6 years ago.jpgHome booster 6 years ago.jpg
 
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I understand the concept and I would have this placed anywhere. However I am not so keen on the idea of water storage tanks for contamination issues. Maybe a sealed tank that contains just steel and air, no other materials ? (not like the ridiculous megaflo which has something like a polyurethane baffle which gets covered in mold and dirt and is impossible to clean).
 
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rallen said:
I understand the concept and I would have this placed anywhere. However I am not so keen on the idea of water storage tanks for contamination issues. Maybe a sealed tank that contains just steel and air, no other materials ? (not like the ridiculous megaflo which has something like a polyurethane baffle which gets covered in mold and dirt and is impossible to clean).
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You have been given all three options generally available for your problem (replacement, accumulator & break tank/booster pump) The direct pumping is NOT an option as it is limited to 12L/M by Law [Water Supply (fittings) Regulations 1999] without notification to your Water Undertaker (as it happens even drawing more than 12L/M indirectly by pump is suppose notified)
There is No magic answer.
Your issues with storage / boosting are unfounded, just think about any high rise building the main water pressure will not reach up passed the first ten floors so all are boosted.
The break tank will need to be fit for drinking water i.e. WRAC approved, it will need a class AB air gap, sealed lid with filtered overflows & vent etc.
It would not be made of steel in a domestic application due to ongoing maintenance issues with steel, water & air causing rust.
Lastly your problem with Megaflo's does not apply, firstly because it is a hot water cylinder & so contains water which is classed as category 2 (not wholesome / drinking water) one which has been impaired by a change in it's temperature or taste & secondly if you have mold on the inside of your Megaflo you really do need to turn the thermostat up a bit higher !!!
 
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Ray Stafford said:
Not if they were in parallel?

You can absolutely forget the warranty though.

And it's a bit like asking if you can bypass your meter. Yes you can, its just that it is illegal.
Click to expand...

with his issue what would happen he wouldn't be able to pull more than 12l from the mains, both pumps will kick in a try to pull from each other.

result would be a very ruined pump and one with a huge amount of wear on it very quickly !!!
 
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chris watkins said:
You have been given all three options generally available for your problem (replacement, accumulator & break tank/booster pump) The direct pumping is NOT an option as it is limited to 12L/M by Law [Water Supply (fittings) Regulations 1999] without notification to your Water Undertaker (as it happens even drawing more than 12L/M indirectly by pump is suppose notified)
There is No magic answer.
Your issues with storage / boosting are unfounded, just think about any high rise building the main water pressure will not reach up passed the first ten floors so all are boosted.
The break tank will need to be fit for drinking water i.e. WRAC approved, it will need a class AB air gap, sealed lid with filtered overflows & vent etc.
It would not be made of steel in a domestic application due to ongoing maintenance issues with steel, water & air causing rust.
Lastly your problem with Megaflo's does not apply, firstly because it is a hot water cylinder & so contains water which is classed as category 2 (not wholesome / drinking water) one which has been impaired by a change in it's temperature or taste & secondly if you have mold on the inside of your Megaflo you really do need to turn the thermostat up a bit higher !!!
Click to expand...

I think that is a (UK only?) design choice.
 
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Is it a design decision based on law, UK only or based on EU directives ? That is what I meant when I asked is it UK only. Because things in EU are very different so I am wondering if it is law, tradition, UK only, imported from EU and so on.
 
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its a law based on design. as said pulling more than 12 ltrs is likely to have an adverse effect on your neighbouring property's.

you wouldn't be very happy if when you opened a tap and the water got pulled away while a neighbour was running a shower.....
 
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Ah misunderstanding, I was not talking about the 12lt/min. I was talking about vented/unvented hot water cylinders. In EU countries hot water from the tap is drinkable, cookable etc
 
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