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low water pressure

low water pressure

low water pressure

(OP)
I have 3 floor building. There is not enough water pressure in taps and bath rooms. the existing 2 set booster pump is GRUNDFOS CR 20-02. Water flow is 92 gallon and 72ft head. the system vet old, I wand upgrade the system with higher capacity. I got proposal with LOWARA pump, with same flow rate and 144 feet head. MODEL SV-22 04. What you think, does it work and solve the problem? Pipe size 2inch ppr.

thanks
moideen

RE: low water pressure

What pressure is available now at your high point, was there sufficient pressure when firstly installed and run - have you checked the discharge pressure at the pump?
In theory the Lowara should do the job and give higher flow and pressure from the system.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

RE: low water pressure

(OP)
Discharge side 2.5 bar. My question is if increase only the pump head with same previous flow rate, does it increase the pressure?

RE: low water pressure

The Grundfos pump should have come close to satisfying your requirements for pressure on the 3rd floor.

You should check the pressure coming into the building, the pressure on the discharge of the pump, and the pressure on the 3rd floor prior to purchasing a new pump.

Yes, it should provide the same flow at a higher pressure.

RE: low water pressure

Is this new (Never Ever Worked) or a few years old?

RE: low water pressure

Is your problem pressure or flow?

If no other outlets are open, do you have enough pressure and flow at the taps on the top floor?

If yes, then I suspect you have too much flow going on normally and you need to add flow capacity as well as pressure.

Maybe your pump is old and not able to supply all the outlets?

Mind you what I assume is 92 US gallons per minute is 350 litres per minute. This seems quite a lot, but how many flats / units etc does it feed?

You need to work out what your demand is before you decide on the size of a new pump.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: low water pressure

72 feet head is barely adequate for static conditions and with any sort of demand and headloss will have barely any pressure at the third floor. the new pump should provide adequate pressure. without knowing the demand, impossible to tell if it provides adequate flow rate. you would need to have a fixture count for the building.

RE: low water pressure

(OP)
LittleInch: problem is pressure. If suppose close the all tap, it do not build up the pressure on discharge side gauge. . I don’t know the history of the system. I planned to upgrade the system instead of repairing. If the repairing not success, I will lose its repairing cost. The existing pump head is 72 and flow rate 92 us gallon. I got a proposal from contractor for new system. They have increased the head (144 ft) only but the flow rate is same (92). My idea is to increase the flow along with head. if suppose there over flow can be controlled and avoid the risk.

RE: low water pressure

(OP)
cvg: i want to know more about 'fixture count'.can you expalin

RE: low water pressure

What is the inlet pressure to the pump, has this pressure changed since the initial installation?

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

RE: low water pressure

Just be careful not to overdo it. If the existing pumps are worn out, performance will be lower than it was originally. So if you "double" the original new pump specs, you might get "triple" what you are experiencing now. I'm being deliberately vague, just trying to illustrate the general idea that what you have down probably does not represent the full original pump performance.

RE: low water pressure

(OP)
THANKS TO ALL YOUR RESPONSES, I WILL RECHECK THE SYSTEM AS YOU ADVISED

RE: low water pressure

(OP)
CVG: is the fixture value is in gpm or ltr?

RE: low water pressure

That is not correct. Use the method posted on 20 Jan 16.

RE: low water pressure

(OP)
OK, this is lengthy document ced engineering, if you have particular paper please upload here, or i will check and extract it.

RE: low water pressure

look at table 2

RE: low water pressure

It takes more than just a few lines on here to explain how to design such a system. Suggest you take the time to review the concepts in the paper.

RE: low water pressure

from the few details I have seen your system is under-designed on all counts. according to the fixture count, your proposed flow rate is way too low. The pipe size is too small for the recommended peak flow. your proposed pump flow rate is too low and TDH is marginal or inadequate assuming your small pipes. assuming that your existing pump runs off the end of the curve most of the time, I am surprised you can get any flow at all up to the third floor. I would think your proposed new pump will not solve the problem

RE: low water pressure

(OP)
please find the calculated value attached,162 gpm required.there is already two set pump,it can be divide in to 82 gpm each with new system. but the pipe size is 2" discharge, then 7.8f/s velocity and 11.7 ft head loss/100ft. please check the values are correct.i forget to say some stories about the building.the new hoter group take the building for ther staff accommodation. i dont have have any previous condition about the building. the new group increased the water demand by fixing additional sinks...etc.the fixture details are prepared by counting manually.

RE: low water pressure

Your work effort looks much better.

The pipe velocity is normally designed to maintain a velocity of 6 ft head loss/ 100 ft to minimize piping noise.

Note that the spreadsheet values are conservative, and the water use will never exceed those values in the spreadsheet. I see that you are in the Middle East. There is more water usage here in the States than the rest of the world and the spreadsheet reflects it.

The drawing is hard to read, it would be easier if you printed it in gray scale.

RE: low water pressure

QUESTION. Do you have good flow and pressure on the ground floor without the pump on. Provide us with an idea of that first. See you. Pumpingtips

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