Electricity Saving Tips For Homes And Offices

Pumping systems without overhead tanks can significantly increase electricity bills of a group housing society

By on April 22, 2016

A few months back we got a call from the management committee of a luxury residential complex in Mumbai to help them on their very high electricity bills. Surprisingly their common electricity bills were so high that their monthly maintenance bills were as high as what a family would pay as rent in any other society in the city. On a walk through audit we found that although the lighting used in the complex was most efficient, what was causing high electricity bills was the hydro-pneumatic pumping system that was installed in the building. It is a system without an overhead tank, and the reason given to the society for not having an overhead tank was that the building lies in an earthquake prone zone. The intent of this article is to explain the differences between hydro pneumatic and a regular gravity based pumping system and also to alert the buyers of a new flat to check the same to prevent high electricity bills.

What is a Hydro Pneumatic or pressure booster pumping system?

A hydro-pneumatic pumping system has a ground level storage tank instead of an overhead storage tank. Pressure sensors are installed at various parts of the plumbing in a building that make sure that there is a constant pressure of water everywhere. Whenever a sensor senses that the pressure is low, the pump close to the ground level storage tank starts and pushes the water up to the level where it is required. It maintains the same pressure everywhere.

What is traditional gravity based storage system?

Traditionally most high-rise buildings have a water storage tank at the top. Pumps installed at the bottom of the building push the water to the overhead tank. The pumps are run for a few hours a day to ensure that the water is adequate in the overhead tank. If right size pump is used for a given load the pumps can run close to the best efficiency point during the time of operation. The distribution of water from the overhead tank to the houses happens though gravity (or the weight of water) and there is no electricity required for the same.

Challenges with a Hydro-Pneumatic pumping system

At a high level a hydro pneumatic system looks neat and sophisticated but the problem is with the efficiency of the system. In the building we evaluated, every time anyone opened a tap for water or used water in the bathroom, the pumps got switched on. We observed that it started and stopped almost every 2 seconds. Any pump takes higher current to start up (6 to 7 times more than stable operation) and since the pumps were starting very frequently, the electricity consumption was very high. Extra energy is also required to achieve constant pressure across the building. (source: energy manager training)

The other drawback of such a system is that it will not work in places where there are frequent power cuts. Although there are pros and cons of both the systems as listed on this link: wiki answers, from an energy efficiency perspective, a hydro pneumatic system is just too expensive to operate. The owners of the flats in the building we visited do not have any other option now but to operate it as it is. But had they known about it earlier, they would have probably made a different decision.

Source of Information

http://wiki.answers.com/Q/Difference_between_Hydropneumatic_and_Gravity_system_of_water_supply

http://www.energymanagertraining.com/Journal/24092005/Domesticpumpingandplumbing.pdf

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  • Venkita Giri

    If the hydro pneumatic system works properly, the pumps will not start and stop often. In this particular system, the pressure tank could be the culprit. The pressure tank has a bladder inside which is pressurised with air and the pressure inside depends on the head of water required. This must be fairly large depending on the water consumption. Typically for a home, the volume required is about 20 litres. If the bladder is punctured or if the air pressure is too low, the pumps will start and stop frequently. If the system is maintained properly, this is an ideal system for high rise buildings. I have installed one for my single storied house and it is working wonderfully well.

  • Ashok

    hello sir,

    I would like to get more information on this. Take an apartment with 100 units in it as an example, with around 15 hp hydro pneumatic pumps with VFD. Then what will be the power consumption?? It wont be running at its max capacity/15 hp whole day.. plz reply

    • https://www.bijlibachao.com Abhishek Jain

      Difficult to comment. Firstly you have a VFD machine which should not have efficiency losses as what a non VFD machine would have if it runs at lower load and for a lesser period. A lot will depend on it’s efficiency levels are the load at which it is running. Also estimating load is extremely difficult. So I would say that it has to be measured by using an energy meter. I cannot give you a number just by doing some calculations.

  • Saurabh Chhonker

    Dear Sir,

    My household electricity bill is coming quiet high even in winter season, so this led me to find its root cause and particularly in my case it is the water pump.
    reading your blog i have installed super fan fans , led lights,refrigerator and AC also.But i could not find a suitable pump from your blog.I live on first floor and
    have an overhead tank of 750 ltr. Since the motor has to draw water from the municipal pipeline which has 4 mtr horizontal distance and then 3 mtr vertical for first floor,also 3 mtr overhead water tank. so please suggest me an efficient water pump for my household use.

    • https://www.bijlibachao.com Abhishek Jain

      Hi Saurabh,

      What you need for your house is a tullu pump (small pump). Typically efficiency is not such a big factor for such a small sized pump. You can go for any good brand just for the sake of reliability.

  • Ajay Sharma

    Since this is an apartment/hotel then they should have installed solarpower cells at rooftop and run pumps from that power bank in day time. This could save a lot of electricity. Is it possible? Now govt. is giving more stress on solar power than before for govt organization building utilities.

    • https://www.bijlibachao.com Abhishek Jain

      Hello Mr Sharma,

      A grid connected solar rooftop would be really good for a commercial setup. It would have roughly 5 years of payback (depending on your city and tariff). If you are in Mumbai then it may have faster payback as the tariff in Mumbai is super high. But in general it should be about 5 years payback for commercial setups.

  • antonio bungcag

    sir, I am a teacher and the school where i teaches doesn’t have water. i want to draw water from a shallow well or a deep well and store the water in a an overhead tank. what do i need ? what shall i do? My students are finding a hard a difficult time fetching water from a distant river. pls. help me.

    • https://www.bijlibachao.com Abhishek Jain

      Hi Antonio,

      You should consult a pumping engineer in your area who can help you setup a pump to do the job. It should be a straight forward job for such a person.

  • Shubham Agarwal

    My industry power bill is very high, I want to reduce it. The power factor is 0.99. But still the units being consumed are very high according to the load.

    • Bijli Bachao Team

      Hello Mr Agarwal,

      If the power factor is good, then the only thing that you can do is look at all the machines & appliances that are there in your factory. They need to be efficient. Other things that you can do is: At many places the tariff is lower at night (for commercial connections), so you may want to shift use of some machines at night (if possible). You may hire services of a good energy auditor and s/he can help you find possible solutions.

  • Rajesh tandukar

    Dear sir, it will be of great help if you will tell me how to supply water in the house, kitchen bathroom etc. constantly as neccessary, without installing overhead water tank . There must be some way. Please respond . If this system works then I could do some marketing also . Thank you.

    • Bijli Bachao Team

      Hello Mr Tandukar,

      You will need a pump and pressure sensors that will check the pressure of water and push it through pump when pressure goes down. Local storage would be required and the sensor will sense pressure in that, but it will not be as huge as overhead tank. But it is highly energy inefficient way of managing water.

    • rajesh tandukar

      Dear sir thanks for your response. As you have mentioned, Iwould like to know if this method will work up to supplying the water to the height of 40feet or how much less. I could build a storage tank on the ground floor capacity up to thousands of liter. Any suggestions…

    • Bijli Bachao Team

      Hello Mr tandukar,

      You will need a small tank at 40 feet. It can be a 6 lts tank as well. But something to check pressure and start the pump to push water as soon as the pressure in the small tank on top goes down.

    • rajesh tandukar

      I am not able to understand your idea…..please be more clear to the vision……

    • Bijli Bachao Team

      There are 4 things required if you cannot build a big overhead tank: 1) Smallest possible overhead tank that can store some water 2) A sensor in the small overhead tank that measures the pressure of the water in the overhead tank 3) A big tank at the bottom of the building that stores the water and 4) A pump that can push water from the bottom tank to the overhead tank whenever the sensor (mentioned in 2) senses low pressure in the overhead tank.

      What this does is that whenever you use water for some work, the pressure in the small overhead tank will decrease. The pressure sensor in the overhead tank will send a signal to the pump at the bottom to start pushing some water in the overhead tank. The pump will start and push the water that is collected in the tank at the bottom to the overhead tank and will refill it.

      The result would be: as soon as someone uses a flush tank in the house, the pressure in overhead tank will drop and the pump at the bottom will start and refill the overhead tank with water. This way you may not have to build a big overhead tank.

  • Dr. nishanth

    Sir I am facing a problem with this wate pressure pump. Everytime there is a power cut there is absolutely no pressure in all the taps and showers. is there a solution to this problem. ? the tank Is at a higher area and somehow gravity does not seem to help . Is it the fault of the pump? Any help would be most appreciated

    • Bijli Bachao Team

      Hello Dr. Nishanth,

      You may try using inverter battery backup for the same.

    • Dr.nishanth

      Thanks for the reply. But is there a way of increasing pressure without use of an inverter.

    • Bijli Bachao Team

      Hello Dr Nishanth,

      Ideally gravity should be able to help you but if that is not helping then you need electricity to power it up. Cannot think of anything else that can help.

  • Chinmay Harkare

    Dear Sir, I am an MTech (Electrical) student and I may be wrong, but wouldn’t a VFD provide tremendous savings in a scenario like this? Firstly it’s a pump load which in itself is great for energy reduction by VFDs and secondly, it’s also a variable flow application right from a single tap being open to peak load condition. Please reply…

    • Abhishek Jain

      Hi Chinmay,

      A VFD will save in most situations, so it will save in this situation as well. So your understanding is right, a VFD pump will save in this situation. In fact a VFD pump will save even in a situation where there is a overhead tank.

  • Prajuwal

    Dear sir,
    We are going to live in 12 storey building.Around 48 flats of 2 Bhk ( Approx.670 sq.ft.)
    We dont have overheard tanks.
    We are planning for hydro- pneumatic system for our building.

    Request you to share your views as per below mentionedabout points.
    1. We have to pump the water 24*7. In this regards, How efficient the pneumatic system for the building.
    2. What type pump ( salient features) we should incorporate in the building.
    3. What is approx cost of the pumps.
    4. What are merits and demerits of hydro pneumatic system for the building.
    5. Please share data sheet of hydro pneumatic system for the high rise buildings.

    Regards,
    Prajuwal

    • Abhishek Jain

      Hi Prajuwal,

      We do not have much data around hydropneumatic systems but we did observe one such system during one of our audits and the results are mentioned in the writeup above. This kind of system is not very energy efficient as the pumps keep switching on and off all the time and the pumps are never able to achieve their optimum efficiency levels. For the building we measured (a 15 storied building with 3 flat on each floor), the common electricity bill was about 3 lakhs a month with 2 lakh coming from pumps only.

  • brsinha

    hi,, can you share name of the society where it happened? when did this happen? has there been any developments in this area to reduce electricity bill? can you share the details if you have any. Thanks a lot in advance.

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