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Thread: Stronger Pump for Higher Pressure

  1. #16
    Sprinkler Guy Wet_Boots's Avatar
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    If you want to solve your dilemma, then learn what the insides of a jet pump look like, then compare to diagrams of the pumps you can get. No question that Jet pumps can be had in the UK, if you look at the Grundfos pages.

    A jet pump takes the basic single-stage centrifugal pump a step further, by sending some of the output water back to the input side, using a nozzle and a venturi. The result is higher output pressure, at the cost of some of the maximum flow (which you weren't going to use anyway) - the right combo of pump and ejector (nozzle + venturi) assembly gets you up to 80 psi output pressure.

  2. #17
    DIY Senior Member Bob1000's Avatar
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    Default Multistage / Jet pumps

    Quote Originally Posted by Wet_Boots View Post
    If you want to solve your dilemma, then learn what the insides of a jet pump look like, then compare to diagrams of the pumps you can get. No question that Jet pumps can be had in the UK, if you look at the Grundfos pages.

    A jet pump takes the basic single-stage centrifugal pump a step further, by sending some of the output water back to the input side, using a nozzle and a venturi. The result is higher output pressure, at the cost of some of the maximum flow (which you weren't going to use anyway) - the right combo of pump and ejector (nozzle + venturi) assembly gets you up to 80 psi output pressure.
    That is what I exactly did and I found that the only available good quality pump here which can do up to 6 bar ( 87 PSI) is that twin impeller Ebara 2HP one
    However , as Valveman discovered , Ebara have now a new product called Matrix pump which is a Multi-stage Horizontal pump( 8-9 impellers) that can do 10 bar ( 145PSI) with very small power 0.45 KW as I can see from the pump curve on website , I contacted the Ebara company for more technical details because it is marked NEW at their web site

  3. #18
    Sprinkler Guy Wet_Boots's Avatar
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    Try "nozzle" and/or "venturi" as search terms for the kind of pump you could use. No question that boosting more than 85 psi puts you in need of a multistage pump. 145 psi? Pop!! goes your plumbing.

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    DIY Senior Member Bob1000's Avatar
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    Quote Originally Posted by Wet_Boots View Post
    Try "nozzle" and/or "venturi" as search terms for the kind of pump you could use. No question that boosting more than 85 psi puts you in need of a multistage pump. 145 psi? Pop!! goes your plumbing.
    will do....... , but of course I would never use any working pressure settings more than 85 PSI but it is always good to have a bigger capacity pump that can boost that much without struggling or needing any city pressure
    My idea as I said before is to set the pressure switch to say 60/80 then either use a PRV on the downstream set to 60 psi or use a CSV set at 85psi

  5. #20
    Sprinkler Guy Wet_Boots's Avatar
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    It would be nice if the pump itself was not capable of doing damage. That's the advantage of using a jet pump for pressure boosting. I would still not abandon the idea of finding a suitable jet pump, since you'd only need half a horsepower, versus the 2 HP you're talking about. But if you can only use products by Ebara, you take what they got.

    (pokes around the Ebara website, while muttering curses about tech sites using frames)

    Try these for size ~ if that link works, you are looking at their 'self-priming' pumps, and some of them are jet pumps They even say so

    There is a 'hidden' danger to using booster pumps, which happens if the pump is too strong in comparison to the water supply. The pump will create 'negative pressure' in the supply lines upstream of it, and an underground leak in said lines becomes a source of contamination, and a danger to health. This 'negative pressure' problem is averted by selecting a pump that is incapable of moving more water than the supply line can deliver. And that's where a fractional-horsepower jet pump comes in. Even if you tried a multistage pump, you can find a fractional-horsepower model that has a limited flow capacity. Limited pump flow equals pressure-boosting safety.

  6. #21
    DIY Senior Member Bob1000's Avatar
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    Default I got a new self priming !

    Quote Originally Posted by Wet_Boots View Post
    It would be nice if the pump itself was not capable of doing damage. That's the advantage of using a jet pump for pressure boosting. I would still not abandon the idea of finding a suitable jet pump, since you'd only need half a horsepower, versus the 2 HP you're talking about. But if you can only use products by Ebara, you take what they got.

    (pokes around the Ebara website, while muttering curses about tech sites using frames)

    Try these for size ~ if that link works, you are looking at their 'self-priming' pumps, and some of them are jet pumps They even say so

    There is a 'hidden' danger to using booster pumps, which happens if the pump is too strong in comparison to the water supply. The pump will create 'negative pressure' in the supply lines upstream of it, and an underground leak in said lines becomes a source of contamination, and a danger to health. This 'negative pressure' problem is averted by selecting a pump that is incapable of moving more water than the supply line can deliver. And that's where a fractional-horsepower jet pump comes in. Even if you tried a multistage pump, you can find a fractional-horsepower model that has a limited flow capacity. Limited pump flow equals pressure-boosting safety.

    As you recommended , I got a 1HP self priming ( that have some jet effect i think) that can give 4 bar ( 58 PSI) without depending on city pressure

    I connected it in the traditional way to the pressure tank and the pressure switch and works fine because the city pressure today is 30PSI so the pressure switch setting of 50/75 is working fine

    The problem now is the pressure fluctuation during the shower as I said before ....

    And because the CSV is not available in my country ....

    One day , I have got an idea from this wonderful forum about a fitting that can be fixed at the downstream that can do almost the same effect of a CSV, a check valve with a 5mm diam hole drilled in its diaphram and to be fixed just before the pressure tank and pressure switch groupe , that is supposed to DELAY the time that the pressure tank would take to fill and reach the cut out pressure and supposed to keep the pump running continuosly when there is a big faucet fully open ( like the shower for example)

    I did this job today but it did not work , the pump can still fill the tank and reach the cut out pressure WHILE THE SHOWER TAP IS FULLY OPEN

    What I am thinking to do next is , to replace this ( modified check valve ) by (a pressure bypass valve- with adjustable pressure setting - and a proper check valve assembly) for the water going in and coming out from the pressure tank )

    Does that make any sense ? If not , then how I can make the pump run continous during the showr ?

  7. #22
    Sprinkler Guy Wet_Boots's Avatar
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    Only 58 psi for 1 HP of jet pump? Man, that's weak. http://www.goulds.com/pdf/BJS+.pdf (note the inside diagram on page 3, to see how a jet pump works)
    Now I know you said you can't get a Goulds pump, but the flow and pressure numbers can be referred to as 'performance targets' in shopping for a similar pump.

    For many domestic water supplies, fed by a 3/4-inch supply line, my own recommendation for a booster (to supply lawn sprinklers, mostly) would be a 1/3 HP jet pump, which will almost certainly be unable to create negative pressures in the supply line. But for people wanting very high shower pressure, that won't be enough pump.

    But when one reads all the posts in the various threads you have on your home plumbing situation, one could point at one specific problem that needs solved, that of having sufficient flow through the shower head to ensure that the instant heater stays on. This is not a problem you solve with pump selection. You solve it with shower valve/head selection. Find out the performance numbers for heater, and for the shower head and/or valve. If you are truly dealing with limited choices of equipment, one could picture a 'brute-force' fix of adding a second shower head, just to insure a minimum flow requirement is met. We have mentioned shower valves that automatically mix in cold water to reduce the shower temperature. Outside of that, there exist 'tempering valves' that do this in a plumbing line, and separate from any fixture. Something like a tempering valve might be of use to you, if it saves you from ripping out shower plumbing.

    Extreme pressure boosts aren't the solution you want. Constant pressure isn't really needed, either.
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  8. #23
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    I do not see how a mixing valve can help if when the pressure is low, there is not enough flow through the shower head to keep the burner running. You would still need to open up or drill out the shower head, to allow enough flow through to keep the burner light, even when the system is at low pressure, just before the pump starts. Then you would still have more flow through the shower head when at high pressure, before the pump shuts off, and you would have to readjust the temperature setting.

    With a standard shower head you would get about 2 GPM flow when the pressure is at 50, and you would get about 3.5 GPM when the pressure is at 75. This makes keeping the temperature steady impossible. You can also see the pressure fluctuate from 50 to 75 while you are in the shower. Keeping a constant pressure on the shower head, means the flow will be constant and the temperature will not change. I have used a lot of Cycle Stop Valves to solve this problem for other people in the past. I know it works.

    Try your pressure reducing valve to hold a more constant pressure on the shower head. Your pump will still be cycling on and off which isn't good but, the pressure and therefore the flow from the shower head will be constant. Then you won't see the pressure or temperature fluctuate.

  9. #24
    Sprinkler Guy Wet_Boots's Avatar
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    Half a world away, we can't see the complete picture, but people can take temperature-stable showers, even with varying pressures and instant water heaters. You just need some sort of thermostatic valve in the pathway to the shower head. I'm just thinking that there are more solutions than trying for a high constant supply pressure.

    Hard to believe a good pro couldn't have solved this in a day or two.

  10. #25
    DIY Senior Member Bob1000's Avatar
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    Default Congratulations ..it worked !

    Quote Originally Posted by valveman View Post
    I do not see how a mixing valve can help if when the pressure is low, there is not enough flow through the shower head to keep the burner running. You would still need to open up or drill out the shower head, to allow enough flow through to keep the burner light, even when the system is at low pressure, just before the pump starts. Then you would still have more flow through the shower head when at high pressure, before the pump shuts off, and you would have to readjust the temperature setting.

    With a standard shower head you would get about 2 GPM flow when the pressure is at 50, and you would get about 3.5 GPM when the pressure is at 75. This makes keeping the temperature steady impossible. You can also see the pressure fluctuate from 50 to 75 while you are in the shower. Keeping a constant pressure on the shower head, means the flow will be constant and the temperature will not change. I have used a lot of Cycle Stop Valves to solve this problem for other people in the past. I know it works.

    Try your pressure reducing valve to hold a more constant pressure on the shower head. Your pump will still be cycling on and off which isn't good but, the pressure and therefore the flow from the shower head will be constant. Then you won't see the pressure or temperature fluctuate.

    I have fixed the PRV this afternoon just beside the main stop valve of the house , factory set to 50 psi ( I left it as it is) and the pump pressure switch setting is 50/75 psi , I have just finished my shower few minutes ago and it worked very nice !
    I have adjusted the hand mixer only ONE time in the beginning of the shower and that was it ..it lasted in its position all the shower duration while in the past I had to readjust it every time the pump starts

    I have noticed all the time that when I can keep the pump running continuously during the shower there is NO problem at all with instant heater nor temperature adjusting nor any other problem , simply because it gives steady pressure when it is running continuously
    So the problem was caused ONLY by pressure fluctuations nothing else

    so when the PRV kept the pressure almost constant during the pump cycling the problem is solved

    The only disadvantage in that solution is the pump cycling because I got a pilot lamp in the bathroom which goes on when the pump is running and off when the pump stops and I have noticed that it cycles a lot , but I am afraid that this is the only way to solve my problem as long as CSV is not available in my country

    once again , thanks for you all

  11. #26
    DIY Senior Member Bob1000's Avatar
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    Quote Originally Posted by Wet_Boots View Post
    Half a world away, we can't see the complete picture, but people can take temperature-stable showers, even with varying pressures and instant water heaters. You just need some sort of thermostatic valve in the pathway to the shower head. I'm just thinking that there are more solutions than trying for a high constant supply pressure.

    Hard to believe a good pro couldn't have solved this in a day or two.

    As I said before , my problem is a pressure problem nothing else , when I could obtain a constant pressure I could adjust the other aspects to suit this pressure i.e the tap opening of the hot and the cold mixture

    The instant heater has also a burner control knob so if the minimum flow hat keeps it running is producing very hot water you can just reduce the gas as much as you like to compromise between the flow and the temperature . and that setting is not required to be done often but just changing from winer time to summer time etc

    But all that have never worked untill the pressure is constant

    The only negative point of the present case is the pump cycling and the difficulity to keep the cut out pressure 75 PSI when the city pressure is very low in the peak time of summer because as I said before the pump can give only 56PSI .... same old story .... I can NOT find any jet pumps that can give 75 PSI on its own

    The only pump that I found that can give 6 bar or 87 PSI is that Ebara 2HP twin impillers that I still keep and I think I have to fix it in summer if I failed to find a small jet pump similar to the Goulds that is not available here.

    Anyway , one cant take every thing lolll thank you very much for all your help.

  12. #27
    Sprinkler Guy Wet_Boots's Avatar
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    Quote Originally Posted by Bob1000 View Post
    As I said before , my problem is a pressure problem nothing else , when I could obtain a constant pressure I could adjust the other aspects to suit this pressure i.e the tap opening of the hot and the cold mixture

    The instant heater has also a burner control knob so if the minimum flow hat keeps it running is producing very hot water you can just reduce the gas as much as you like to compromise between the flow and the temperature . and that setting is not required to be done often but just changing from winer time to summer time etc

    But all that have never worked untill the pressure is constant

    The only negative point of the present case is the pump cycling and the difficulity to keep the cut out pressure 75 PSI when the city pressure is very low in the peak time of summer because as I said before the pump can give only 56PSI .... same old story .... I can NOT find any jet pumps that can give 75 PSI on its own

    The only pump that I found that can give 6 bar or 87 PSI is that Ebara 2HP twin impillers that I still keep and I think I have to fix it in summer if I failed to find a small jet pump similar to the Goulds that is not available here.

    Anyway , one cant take every thing lolll thank you very much for all your help.
    Boy, what a drama. Always one more previously-unmentioned detail. This time, it's a control setting for the water heater. In the US, old-fashioned shower valves are outmoded, and not to code. At a minimum, a pressure balanced valve is required, and users of those don't get nailed with a blast of heat when a toilet gets flushed. The thermostatic shower valves are a step beyond the pressure-balanced ones.

    Glad you got a result you can live with. I still repeat my assertion that a good pro could have nailed this problem in hours. They know when to shift their focus from a small detail to a wider picture.

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