Momentary additional pressure required

Discussion in 'Pumps and Tanks Well Forum & Blog' started by Bob1000, Dec 28, 2008.

  1. Bob1000

    Bob1000 New Member

    Messages:
    114
    Location:
    Egypt
    I have a booster pump connected to the city line to boost the pressure and I am very happy with the system in 95% of the time but I got a small problem at very few occasions when the city pressure is very very low ...
    My present pump set up is as follows :-
    1)1 HP self priming pump which can produce 60psi from a bucket of water ( zero city pressure)
    2)Pressure switch setting 60/80 psi ( that setting is a must because I have a house of 3 flats on top of each other and the pump is in the garden so i cant reduce it also I can not reduce the differential either because this is the way the Square D pressure switch works )
    3)Pressure tank (6 Gallon)
    4)pressure regulator fixed at the flat entrance and set at 55psi to assure steady constant pressure during the shower
    ALSO I NEED THAT 55PSI PRESSURE AT THE FLAT ENTRANCE BECAUSE I HAVE LOT OF PRESSURE LOSSES DUE TO NARROW PIPING
    5)OFF Delay ON delay timer switches off the pump after 5 minutes of continous running if it did not switch off by the pressure switch , then switchs it on again after 10 minutes and repeat the cycle untill city pressure comes back
    From my practical use of the system I found out that during my water usage and comsumption in 95% of the time the pump would not run more than 3 minutes at a time before the pressure switch switchs it off .

    But lately the very low city pressure periods started to happen more often so what I am suggesting to do is TO FIX ANOTHER SMALL PUMP IN SERIES WITH THE ORIGINAL PUMP TO GIVE MOMENTARY ADDITIONAL PRESSURE TO MAKE THE PRESSURE SWITCH SWITCH OFF THE PUMP , BUT LET IT ONLY RUN IF THE ORIGINAL PUMP FAILED TO SWITCH OFF BY THE PRESSURE SWITCH AFTER 5 MINUTES , AND THAT OF COURSE WILL BE BY FIXING A DELAY TIMER TO THE SMALL PUMP .

    NB
    This type of self priming pump is the only 2 phase max pressure pump I can obtain in my area so again I would not be able to obtain a shallow well pump as has been previously suggested here

    I APPRECIATE VERY MUCH ANY SUGGESTIONS , THANKS A LOT TO EVERY BODY IN ADVANCE AND HAPPY NEW YEAR TO ALL OF YOU .
  2. Gary Slusser

    Gary Slusser That's all folks!

    It sounds as if you aren't getting enough water from the city supply; 0 psi says no water. If so then you can't boost 0 until there is water for the booster pump to pump. IOWs, suck on straw in an empty milkshake container and get very little to nothing and then add more straws thinking that would help...

    The only way to fix that is a storage tank the city system fills and then you suck/pump out of it.
  3. Bob1000

    Bob1000 New Member

    Messages:
    114
    Location:
    Egypt
    0 psi is a very seldom condition

    In the event of 0psi , I have fixed a dry running protection which would shut off the whole pump system but that happens very seldom
    I dont like to have a storage tank because of the high possibility of contamination plus the city line has water in 99% of the time and water is usually available in a reasonalbe pressure which makes my pump build pressure enough to shut off the pressure switch withe the 60/80 psi setting .
    My question is what I can do in the rare times when the pump cant switch off at that setting ?
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,689
    Location:
    Cave Creek, Arizona
    pump

    I really do not understand how you intend the second pump to operate, but in most cases it would not be necessary, and would be counterproductive if it were installed. And where do you stop? If this doesn't do what you wish it to, do you put a third pump in series with the other two?
  5. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    I agree with Gary and HJ. Your going about this all wrong all because you bought the wrong kind of pump in the first place. Self priming pumps are for irrigation not pressure boosting.

    Where are you located that you can't find the right pump. There is the internet if nothing else.

    bob...
  6. Bob1000

    Bob1000 New Member

    Messages:
    114
    Location:
    Egypt
    The second pump would stop when the pressure build up reaches 80psi .

    What I plan is that when the city pressure is too low to allow the main pump to build up 80psi for the pressure switch to shut off , usually the pressure manometer reads 70 to 75 psi so the second pump would kick in after 5 minutes of the main pump struggling but failed to shut itself off ( I can make that timer setting any other value say 3 min) , and that is to boost that pressure and make it reach the cut out value of 80psi , so the second pump would boost by only 10 psi max which is very easy for any 1/2 hp pump or even less to do it .
    I am sure it would work because it would be like a 2 stage pump but the advantage is that you would use one stage of it in 95% of the time and you would need the second stage to kick in only in few times .

    The appliation is located in Egypt and the shallow well pump is not used nor available here simply because there are no wells feeding houses here .
  7. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    I would let you build me a timing device that could be used for many applications, because it sounds like you know what your doing in that department. The pump installation and regulation engineering on the other hand may need just a bit of improvement.

    bob...
  8. Bob1000

    Bob1000 New Member

    Messages:
    114
    Location:
    Egypt
    Please suggest/ comment

    Hi Speedbump
    Yes I am a civil engineer but I like the Automatic Control bit and like to use it wherever it may help in the unusual cases and it would be a pleasure to help you in that regard if you want.

    What is the bit of improvement you would suggest about the pump installation / regulation?
  9. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    The simple tried and true way.

    A self primer moves a lot of water but typically makes less than 50 psi. A two stage centrifugal will make in the range of 60 -65 psi. The impellers are smaller in diameter, but due to the charachteristics that you would understand better than me, neither work well with a pressure switch. Unlike the jet pump which works great with a pressure switch. The jet pump comes with a pressure switch because it typically does not pump a large amount of water compared to the centrifugal but is able to make the 60 plus pressure with ease and compliments a switch in that way.

    Since your water supply is so varied from almost decent to non existant, no number of pumps will make it better than one properly applied pump. Using timers and things not normally used with these pumps is asking for a disaster. Melt down's motor problems and constant fiddling with adjustments.

    Remember, if the water stops flowing, there is nothing for these pumps to get. This is where a temperature sensor would be very handy to protect the pump and fittings.

    The cistern is the best answer to your problem from all you have said. Disinfecting it is not a major deal and would be far easier than trying to get three pumps to work in unison. And you would be far less likely to run out of water when the pipe goes dry.

    bob...
  10. valveman

    valveman Moderator Staff Member

    Messages:
    4,473
    Location:
    Lubbock, Texas
    Anytime you complicate a water system, you make it less dependable. I can't see where your timer would know that the pump is struggling to reach cut-off pressure. Then even if it only delays a minute or two, you may overheat the pump during this time.

    If sometimes you need both pumps to build to shut-off pressure, then I would run both pumps as if they were one. As you said it is like having a two stage pump. Just turn them both on and off with the same pressure switch. You may not need both pumps all the time but, it won't cost much more on the electric bill, and both pumps will already be on when you do need them.
  11. Bob1000

    Bob1000 New Member

    Messages:
    114
    Location:
    Egypt
    OK , Thanks to all of you , am convinced now and I will go for a cistern and also will make the 2 pumps run together just to be able to reach 80psi from the very low head of the cistern .
    I am worried about disinfecting this tank and keeping it clean , any new ideas in the market in that regard?
  12. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    Do you really need 80 psi? With the cistern, you can place it wherever you want it. As long as the city pressure is good enough at times to keep it full.

    bob...
  13. Bob1000

    Bob1000 New Member

    Messages:
    114
    Location:
    Egypt
    I want to avoid pressure fluctuation

    The reason I need 80psi at the pump level is that my pressure switch has a differential of 20psi so it turns pump on at 60 and off at 80 and I fixed a pressure regulator at the flat entrance set at 50psi , the system works very well with constant pressure during the shower no matter the pump is off or on so I am very happy with that setting after so many trials and cold and hot shocks during the shower due to pump start and stop .
    Again , regarding the cistern , I can only put it above ground in the garden , is there a system for keeping it clean and disinfected?
    Last edited by a moderator: Feb 2, 2011
  14. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    With the cistern there will be no differences in in coming pressure like the city water, so one pump with a pressure switch should work fine.

    As for disinfecting, I recommend a Feed Pump. They squirt little dabs of chlorine into the cistern as the pump runs. Or you can do it manually every so often.

    bob...
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