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  1.  
    So using my hugely limited knowledge, it seems to me that I can take a standardish house with stdish water supply and a gas boiler and cut any cold pipe anywhere in the house and insert a large 1000/1500 ltr tank and then fit a whole house rated potable water pump.....then, so long as I have an NRV around about the incoming cold water main everything will work just fine. Love to see a "Yes" answer or even a "Yes but...." would do.......Ta
    • CommentAuthorbarney
    • CommentTimeJun 15th 2017
     
    Yes but...........

    Distribution pipework tends to get smaller as you move away from the source of supply - if you plug the source of supply (ie the tank) into the little pipes, the little pipes can't supply enough water back to the bigger pipes

    On a house, if all you have is the equivalent of a 15mm CWS supply doing everything, then yes - pick a suitable point and put the "T" in - you may need to ramp up the booster pump pressure to suit

    And do check local rules regarding connecting stored supplies to systems - in many cases you will not be allowed to rely on a standard NRV - you would need a specific RPZ valve coupled with an approved double check valve

    If you have a tank supply with a booster, it's more normal to direct the mains water feed to that and then boost the water to where you want it within the house - the tank and booster then providing a bloody big air gap between your stored water and the suppliers main (or branch)

    Basically it's to avoid you pumping manky water from your tank back into the suppliers nice clean potable main and then that being sent to other consumers making you the index case for some horrible water borne infection that kills thousands

    Regards

    Barney
    • CommentAuthorGotanewlife
    • CommentTimeJun 15th 2017 edited
     
    Thanks Barny, naturally this being Italy I won't check the regs or speak to anyone else about the work, but I will ensure the NRV is 'good', I might even look up what on earth a RPZ thing is! Has to go in a downstairs, but actually underground storage room - no chance of getting the supply there.

    One concern though, as I started to think about this (it's for a client who has high water pressure and no flow - think 6 year old boy having a widdle) and the summers only just started!!! So:

    With a full tank, tap opens, pressure drops, pump starts, tap is closeds but ballcock on tank now open, so pressure low still, pump carries on pumping, in effect circulating the water - how does it 'know' the difference between its own ballcock being open and a tap?

    I must be missing something silly I guess:shamed:
    • CommentAuthorgyrogear
    • CommentTimeJun 15th 2017 edited
     
    G@NL, I think you are describing hysteresis...

    I suspect there needs to be a "buffer" volume in the tank, whereby when tap opened, the tank level drops but the pump does not come on straight away; rather it comes on when a "lower limit" level is reached, and continues running until the upper level is reached, at which point the pump is turned off. During the meantime the tap has done its thing, but the tap function is now divorced from the pump function.

    Or Something Like That...

    Requires tank level sensor units.
    http://www.vp-scientific.com/liquid_level_sensor.htm

    gg
  2.  
    Thanks gg but No that isn't what this set up is about., This set up provides pressurised water to the whole house, ie it has to come on the instant a tap is opened, if not no water will flow out of the tap! It is usually installed in the way Barney describes, and indeed I have fitted in my house, where the mains water is isolated from the house and the tank and pump are the only thing to provide water, and usually in a basement rather than any sort of gravity flow. Hopefully I have missed something.
  3.  
    It sounds like what you will need (if I am understanding the problem correctly) is a holding tank that is filled from the (v. slow) mains then a pump to distribute at reasonable speed and pressure. If this is correct then I would suggest an open tank filled from the mains controlled by a ball valve and then a pump takes water from this tank to a pressure vessel which supplies the taps. the pump is controlled by a pressure switch on the pressure vessel. Open a tap, the pressure drops and the pump starts. Close the tap and the pump runs until the pressure switch turns off the pump. Much the same as a well except the source is the mains fed unpressurised holding tank.
    • CommentAuthorgyrogear
    • CommentTimeJun 16th 2017
     
    Posted By: GotanewlifeThis set up provides pressurised water to the whole house, ie it has to come on the instant a tap is opened, if not no water will flow out of the tap!


    OK, apologies for not reading straight, I think I get it - it is like these (very...) French pressurized WC flush mechanisms one encountered years ago, in closets "à la persian version", - generally in bars etc. -- I have been desperately searching my memory for the name that was always stamped on them...

    Does this help any...
    https://www.thespruce.com/pressure-assisted-toilet-works-1824909

    A pressure-assisted toilet works by compressing air in the storage tank as pressurized water from your home plumbing system fills the storage tank. Then, once the storage tank is charged, the compressed air blows the water out under pressure when you depress the flush lever—the action is like blowing water from a straw.

    This creates a strong flow of water that cleans the bowl better, removes waste better, and flushes further than a gravity-fed system. In fact, pressure-assisted toilets can flush 50% further than gravity toilets, resulting in cleaner waste pipes and less chance of clogs down the road.

    HEALTH WARNING :
    do not read the above text while drinking your morning tea...

    :devil:

    gg
  4.  
    gg - I think you are confusing things on this thread thanks all the same but I need to focus it on the info I need.

    P-in-H Everything you say is correct, I designed and installed my own similar system in my own house you may recall -vented tank (actually no need for a pressure vessel with modern inverter powered pump) BUT BUT BUT, the issue I have is that usually this tank is fed by the mains feed into the house (or from a well), then the tank/pump feeds the rest of the house - easy - as in the pump feeds the house, it doesn't also feed the tank ONLY the mains water pipe feeds the tank!

    But the whole point of this thread is that I understand how all that works but can it be made to work when you CANNOT put the tank between the mains feed and the house, ie can I insert randomly somewhere in the houses cold water pipes a tank, with a ballcock, followed by a pump which senses a pressure drop? Barney says yes but I wondered how the pressure switching works afterwards, perhaps by screwing down input into the ballcock the pressure drop from the ballcock being open can be small enough not to trigger the pump to come on, for example?.
    •  
      CommentAuthordjh
    • CommentTimeJun 16th 2017
     
    I know nothing about the subject but the only way I can think of to make it work is to have a solenoid valve plumbed in series with the ballcock valve. When the pump runs, the solenoid valve closes and stops the tank refilling. When the pump stops, the solenoid valve opens again and the tank refills.
    • CommentAuthorBeau
    • CommentTimeJun 16th 2017
     
    Not sure I fully understand but our spring supply is slow low presure so we have a large storage tank combined with a presure set to provide pressurised water throughout the house. The presure set is a pump combined with and expansion vessel.
  5.  
    gotanewlife - if the pump providing the extra pressure is anywhere other than at the beginning then you will pressurise everything before and after (the pump) which will stop the mains flow due to its higher pressure, assuming you have a NRV at the beginning, otherwise you will pump everything back down the mains. I don't see how you can use one pipe to supply the tank with mains at low pressure and at the same time use that pipe to supply taps at high pressure/flow.
    BUT
    Having read djh suggestion - that would work because you are isolating the tank/ball valve from the system when a tap is opened. With this a pressure vessel can not be used, you would need a shower booster pump and to juggle with the pressure settings to get acceptable working. And you will need a NRV at the entry point and a tank big enough to supply any foreseeable one time usage of water plus a bit.
    • CommentAuthorGotanewlife
    • CommentTimeJun 16th 2017 edited
     
    Posted By: Peter_in_Hungarywhich will stop the mains flow due to its higher pressure,
    Yes for sure, I knew that but not at all a problem.
    Posted By: djhWhen the pump stops, the solenoid valve opens again and the tank refills
    Yes but why would the pump stop, OK someone has turned off a tap but the 'tap' in the tank (the ballcock) is open.
    Posted By: Peter_in_Hungarya tank big enough to supply any foreseeable one time usage of water plus a bit
    The tank has to be big enough to cope with at least a full days loss of water. I will be insisting on 1000ltr and suggesting 1500 (due to entrance door widths will be made up of 500 litre tubes). This particular house is a holiday home that is let out during the summer when the owners aren't there for big bucks.

    Waiting for Barney to show up......
    •  
      CommentAuthordjh
    • CommentTimeJun 16th 2017
     
    Posted By: Gotanewlife
    Posted By: djhWhen the pump stops, the solenoid valve opens again and the tank refills
    Yes but why would the pump stop, OK someone has turned off a tap but the 'tap' in the tank (the ballcock) is open.

    Well, the pump will stop because somebody turns off the tap. I assume such booster pumps are pressure controlled? Or maybe flowrate?

    The question is why, having stopped, the pump doesn't restart because the ballcock is now drawing water. The answer, I suppose is some sort of interlock based on flow through the ballcock valve, but maybe there's a better plumbing solution since that would prevent somebody else drawing any good flow of water until the tank had refilled.

    The tank has to be big enough to cope with at least a full days loss of water.

    It's not clear to me why that is necessary, unless there are other requirements.
  6.  
    If its going to be a rented to tourists property then any solution has to be 1. fool proof, 2. tamper proof and 3. fail safe. Solenoids and interlock contacts will go wrong, usually at 17:30 on Saturday evening when everyone wants a shower!
    Would it be possible to site the tank where convenient and run a new mains feed to the tank?
    • CommentAuthorGotanewlife
    • CommentTimeJun 16th 2017 edited
     
    Posted By: djhIt's not clear to me why that is necessary, unless there are other requirements
    I didn't explain because it is not central to the question. This is semi-rural Italy, where this house is is at the end of a long and very leaky supply line, despite bans on everything but washing and drinking, there is an acute water shortage and a heat wave. Pretty soon they'll start turning off the water serially across areas...probably. These houses need enough water to get them through not less than one full day when occupied by tourists.

    The fool proof and tamper proof I can do, the fail safe is rather more difficult.

    I am visiting tomorrow to see if there is anyway to get the main supply to the room in question, which probably means drilling diagonally down through re-inforced concrete containing who knows what, or perhaps just beam and block with screed, still containing who knows what. As you say the only other logical solution is to site the tank outside, insulate the tank, and above ground pipes, protect from sun, protect pump from external weather, make it look pretty, lay in a mains feed (unless there is room inside for pump where existing mains enters house which I very much doubt), dig up the garden, paths and beds, get the water supply company out or drill holes in walls and take the post meter water there and back.

    If there is a way to have the pressure drop into the tank low enough when filling to not trigger the pump then that would work it seems to me. Tricky to decide it can be done at the outset......
    •  
      CommentAuthordjh
    • CommentTimeJun 16th 2017
     
    You only have to take the mains water feed to the tank, you don't need to take the tank outlet back to the same place; it can be teed in anywhere convenient bearing flowrates in mind.

    Posted By: GotanewlifeIf there is a way to have the pressure drop into the tank low enough when filling to not trigger the pump then that would work it seems to me.


    I don't know about slowing the rate into the tank to reduce the pressure drop; that would make it take longer to fill up again. Perhaps there's a way to do it by measuring the flow rate into the tank and that being supplied by the mains and looking for a difference?

    As regards reliability and failsafe, the question is what's the alternative? Nice showers most of the time is a lot better than cr*p showers all the time!
    • CommentAuthorcjard
    • CommentTime7 days ago
     
    I understand the mental problem you're having with the puzzle, as in your mind you're trying to find an alternative install than the two standard ways this might be done depending on whether the tank is pressurised or not

    You seem to be trying to find a way to pump the mains and have a tank that is part of the whole house plumbing and can withstand the pressure but is sometimes pressurised and sometimes not

    I can only imagine the only way that would work would be to pressurise the tank using air at times when demand exists and depressurising it so the mains can refill it when there is no demand.. and it wouldn't really meet your criteria for operation. Why is the standard non pressurised tank/cistern approach no good?
    • CommentAuthorGotanewlife
    • CommentTime7 days ago edited
     
    Posted By: cjardtank that is part of the whole house plumbing and can withstand the pressure but is sometimes pressured and sometimes not
    No, the tank would not be pressurized at all, ever. The way this works is that there is a ballcock for the feed into the tank and the pump after the tank 'sucks', hence the tank is unpressurised and 'open' to atmosphere otherwise the pump would quickly create a vacuum!!!
    Posted By: djhdon't know about slowing the rate into the tank to reduce the pressure drop; that would make it take longer to fill up again.

    but that is already the case! The maximum water supplied with the mains wide open in 24 hours is barely be more than they need in a day.
  7.  
    Posted By: djhPerhaps there's a way to do it by measuring the flow rate into the tank and that being supplied by the mains and looking for a difference?
    Ahhhh, now that's a good idea 2 flow meters and a tiny bit of electronics to compare - working a bit like an RCD!
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