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Increasing water pressure options

Discussion in 'Plumbing and Central Heating' started by Josh1987, 16 Apr 2020.

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  1. Josh1987

    Josh1987

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    Hi all,

    First time poster here looking for advice as to how we can increase the water pressure in our home, or at least in some parts of it.

    The water pressure in our area is very low, although meets relevant requirements, so we end up with issues if someone runs a sink downstairs and someone is in the shower...etc. In the near future we are looking to install an en suite upstairs and have the bathroom re-done, but naturally do not want all that spend without resolving this in some way.

    The house set up is currently 1 bathroom with an electric shower, sink and toliet. The proposed works would increase this to then include an ensuite with a shower, sink and toliet too.

    The showers would either be electric or mixers (both would be the same), although I suspect the electric shower approach will be easier to manage as have seen various examples where rather than the cold water pipe directly going into the shower, it feeds a small water tank in the roof initially which provides a "buffer" against a drop in pressure around the rest of the house if someone runs a tap elsewhere.

    Does anyone have any advice or solutions - or can point me in the direction to get some sensible advice.

    I should say the house is serviced by a combi boiler which we won't be changing

    Thanks
     
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  3. motorbiking

    motorbiking

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    Is your hot water mains pressure or is there a hot water cylinder? Have you measured the flow of the cold water? home many l/pm?

    you could install a pump but it depends on other factors.
     
  4. muggles

    muggles

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    Is it the pressure or the flow rate that is low? Have you had any tests done to replenish what your static pressure and maximum flow rate are? If not, that would be a good place to start
     
  5. oldbutnotdead

    oldbutnotdead

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    Have you had your supply tested at the point where it enters your house? When was the place built- any lead pipe, shared supplies, that sort of nonsense?

    If you're on a combi then you're a bit limited on increasing the hot water flow rate (unless it is a monster heat exchanger in the thing).

    Have you got room anywhere for a hot water cylinder and header tank? Megaflo (mains pressure hot water) isn't going to work if your mains pressure/flow is poor, you can heat a hot water cylinder via the heating side of your combi (need to install a couple of 2 port valves and an extra controller for controllability).

    2 electric showers would be a very bad idea- using them simultaneously would pull a lot of current. Electric showers are fairly pitiful anyway & best avoided except for emergencies
     
  6. Urban Plumbers

    Urban Plumbers

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    If you are using electric showers then you will always have very poor flow from those due to their nature. (They restrict flow as you can only get so much flow from 7-9kW showers)

    If you want any real advice then you need to supply more information:
    - current water flow per minute in litres (kitchen tap cold usually best for this)
    - current combi size? Kw?
    - standing and dynamic pressure of supply as mentioned
    - Incoming main to the property - what size is it? You may be able to upragde that. (Requires you to dig to the boundary and lay new pipe)

    If you flow drops below 12l / minute you can use relatively inexpensive booster pumps such as salamander iboost or similar form grundfos.
     
  7. flameport

    flameport

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    Unlikely your electricity supply is adequate for 2 electric showers.
     
  8. oldbuffer

    oldbuffer

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    1. As others have suggested, it's unlikely you could run two electric showers. Most homes have electricity board fuses of 100 or 80 amps. A 10kW shower uses roughly 40 amps, so two of those and you are very close to the limit. Boil a kettle and you could be over the limit of an incoming 80 amps. Also, electric showers are generally low flow.
    2. If you are keeping your combi boiler then the maximum flow of hot water you can get from this is likely be between 12 and 15 litres / minute, less if your incoming flow is less. Unlikely to run two decent showers simultaneously, and one or both will go cold if another outlet is opened.
    3. The best approach is to increase the mains pressure and flow. However, from what you say of the area, increasing the pressure won't be possible. A larger pipe between water meter / main and your property might help, but you'd need to in the diameter of at least some of the internal pipework to get the benefit.
    4. There are ways of improving pressure, such as break tanks and pumps, and / or the use of an accumulator. Fairly expensive, and for a tank and pump, makes you dependent on electricity supply for decent flow.
    5. If you have the space, you could consider fitting a cold water storage cistern (CWSC, in loft) and a hot water cylinder (HWC, 1st floor). The HWC could be heated from the combi, perhaps with an electric immersion heater as a standby in case of boiler problems. Cold water to showers could come from the CWSC. You'd need a shower pump to provide pressure to hot and cold to both showers. Hot to other outlets could come from combi, and cold from existing mains connections.
     
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  9. Gasplumber

    Gasplumber

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    Sounds like you mainly need more flow.
    Get your water tested by supplier and see what’s available then get someone in to give you an idea.
    Probably need a new main and new pipes running around the house
     
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  11. Madrab

    Madrab

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    If you can come back to us with flow and pressure figures - specifically dynamic flow and pressure readings.

    If it's that bad you may be able to get away with a mains boost pump but we need the figures first.
     
  12. Josh1987

    Josh1987

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    Hi all

    Thank you for the responses - as suspected a bit of a minefield. To give context on the house;

    - 1970's with it's own feed (i pressume) from the street - every house has its own stop cock out on the pavement. I know one poster suggested digging up the drains and increasing the size of pipe etc, but for obvious reasons I am not keen to do that!

    - Current flow rate I have calculated as 8.8litres per minute - rather crudely taken how long it takes to fill up a 600ml jug (the biggest I have!) and taken the average of 5 attempts. According to the UU website they provide a min pressure of 7m per static head which they equate to being able to fill up 4.5 litres every 30secs which would suggest a 9litre per min flow rate - my crude calcs aren't for off this but certainly lower end of the spectrum.

    On the flow rate point is there a reason why my outside tap and hose can be almost like a rocket v the taps inside - do outdoor taps have a link directly to the mains aswell - we also have a stop cock in the kitchen aswell as the pavement so just wondering if there is some pipework issue the house instead

    - Currently combi boiler max flow is 15.9litres per minute - based on the above then the general water pressure currently seems to be the limiting issue as opposed to the boiler. If this boiler is being maxed out would it be sufficient to feed 2 showers at once? We have a Valliant Eco Tec Plus 838 which looks fairly powerfull from reading around online. @oldbuffer I have space in the loft for your final option can you tell me more/link me in to some solutions. I presume I would need some calcs for a tank in the roof in terms of weight distribution etc

    Once again thanks for the responses
     
  13. oldbutnotdead

    oldbutnotdead

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    Aah. The outside tap is often the first after the indoor stop tap and thus has minimal flow restrictions. Do your volume test on that one & see what you get (your method is sound, you'll get more accurate figures with a bigger bucket).
    Your indoor taps may have internal flow restrictors, standard isolation valves also have a restriction as do flexible tap tails. Add that to a normal number of bends & the supply head can quickly be absorbed
     
  14. oldbuffer

    oldbuffer

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    1. If you have got good pressure and flow from the outside tap, then you may have the option of an unvented hot water cylinder. This would provide mains pressure (almost) hot and cold to all outlets. You would need at least 1.5 bar dynamic pressure (pressure with another outlet open) and a flow of around 20 lpm. Installation is not DIY but must be done by a G3 registered engineer, who should do the necessary notifications to building control. The cylinder could be sited anywhere suited to the provision of the equivalent of an overflow.
    2. If you went for CWSC in loft you would have to pick a spot capable of supporting around 1/4 tonne of water and tank. The tank should be on a platform with weight evenly distributed over as many joists as possible, and an absolute minimum of 3. The platform must be of substantial wooden construction ( 2 x 4s), cross braced, with a flat top of something like 18 mm marine ply. No chipboard under any circumstances. The platform should be wider than the base of the cistern by a few inches in all directions. There are advantages to installing the tank as high as possible, but there must be 450 mm of free space above the tank to allow access to the float valve. The tank must have a proper lid and fittings. You would need to run an overflow pipe to outside, usually under the eaves. The cistern should be insulated to the sides and top, but any insulation underneath it should be removed to reduce the risk of freezing in winter.
    3. The HWC is best sited on the first floor, normally in an airing cupboard.
    4. The primary coil withing the HWC is heated off the central heating side of the combi. You would need a 3 way (or better 2 x 2 way) motorised valves, a programmer and a cylinder thermostat.
     
  15. Josh1987

    Josh1987

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    @oldbuffer thank you for the futher response. I will try the outside tap tomorrow to see if the flow rate outside is much higher.

    In your opinion which solution works best - from reading around it I am leaning towards the CWSC in the loft (we have a large loft and high pitch so shouldn't have any issues with size/enough joists for it to go across...etc) and then associated cyclinder somewhere upstairs. Only because I as I understand it you are removing the relationship with the mains pressure for as long as there is sufficient water in both tanks
     
  16. Madrab

    Madrab

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    I'm sorry but if you have a problem with water pressure and flow just now, moving to gravity hot and cold water will not improve the situation without pumping both hot and cold supplies, unless you can lift the cold water storage cistern to at least 15m above the highest outlet that will be supplied by it.

    Nor will you be able to run the combi from it.
     
  17. Josh1987

    Josh1987

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    Thanks Madrab sorry in my head the potential solution was;

    - Cold water in attic
    - Hot water in a space upstairs
    - Both then pump into the upstairs bathrooms (i guess ideally they would only feed the showers and bath but pressume this isn't possible)

    I guess the risk with this approach is that if both tanks aren't suitably sized, then the respective tanks could empty (as your mains into the combi and cold water would be at a lower rate than out to the showers), if say 2 people were showering and someone was running a bath at the same time (not sure why we would run a bath and shower at the same time?!?!)

    Apologises if I am sounding hard work - it is all new to me, in a house we have only recently bought so very much finding things out as I go and appreciate everyones comments
     
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