How & why to choose & install a water pressure booster pump: this article describes the use of water pressure boosting systems that add a pump and pressure tank to improve water pressure and flow, including improving water pressure & flow on the upper floors of tall buildings.
We explain what a booster pump system is, what components are needed to improve building water pressure, and how to decide if a booster pump or pump and pressure tank set-up is the right repair for bad water pressure in your building. In FAQs & Q&As at the end of this article we discuss adding booster pumps & tanks in series.
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Effect of building height on water pressure: The Home Reference Book points out that Gravity is another source of pres- sure loss. Energy is required to push the water uphill. For every one foot we push water up, we lose 0.434 psi. Another way of saying this is that it takes one psi to move water up 2.31 feet.
A plumbing system will typically lose eight psi of water pressure in a two-story house, getting the water from the basement up to the second floor bathroom. With no water flowing, the static pressure at the street main may be 60 psi, but the static pressure at the second floor basin might be 51 psi. Houses that are above the street or have third story plumbing fixtures, have a pressure disadvantage.
Other Explanations of Poor Water Pressure where a Booster Pump & Pressure Tank May be Helpful
Homes on gravity water systems such as we describe in the San Miguel de Allende case usually install a rooftop water tank or cistern to which water is replenished periodically. The rooftop water cistern provides water to the local building whenever it is needed.
But some homes in such a community may because of their location or construction or because they have no high spot to place their water tank, have only very low water pressure.
Our sketch, courtesy of Carson Dunlop and edited by the author shows a simple one line jet-pump and pressure tank connected to the incoming water line in a building. Our photo at page top shows a typical water pressure booster pump and tank system for sale at Don Pedro's Ferreteria in San Miguel de Allende.
The incoming community water supply line which normally is fed through a pressure regulator and into building supply piping is first connected to a water pump, usually a 1-line jet pump. The pressure regulator control is not shown in this sketch.
The water pump is in turn connected to a pressure tank, possibly a large one to give a good high pressure water supply to the building.
As water is drawn into the home (someone turns on a faucet) the pressure tank feeds pump-boosted water pressure to the building, and as water pressure drops in the water tank, the jet pump draws more water from the community supply line, boosting its pressure into the pressure tank.
Typically the booster pump pressure control switch will be set to operate in the 30-50 psi range, providing good water pressure to the building.
In a private well water supply system this pump and tank combination may be connected directly to the well, that is, the incoming water line shown in the left of the sketch is connected to a foot valve immersed in the water well. at WATER PUMP, ONE LINE JET we discuss one-line jet pumps in more detail. at WATER PUMP CONTROLS & SWITCHES we discuss the pump pressure control switch and how it can be adjusted to provide higher water pressure.
The reason that a typical residential property needs just a one-line jet pump to provide its water pressure boost is that there is already water arriving at the building under some pressure - the pump does not have to combine lift of the water from deep in the ground to high in the building.
Our photo of a pressure booster pump and tank system at left (and at page top) shows that stainless steel parts were used to enclose the pump parts: this system is designed for outdoor use in a non-freezing climate. You can see the pressure gauge and the gray box housing the pump pressure control switches above the stainless-steel covered pump assembly itself.
Some water pressure booster applications may require a more powerful pump than the type we discuss here, particularly if the anticipated water flow or usage rate in the building is high.
Carson Dunlop's chart at left explains that in an individual plumbing system (that is, changing nothing but water flow rate), the water pressure observed at a fixture (and in the piping) will drop off significantly as the water flow rate increases.
This chart explains why the water pressure in your shower may fall off substantially during your bathing if someone else in the building flushes a toilet or turns on the dishwasher.
The chart also demonstrates that using larger diameter piping for the water supply in a building can significantly reduce the pressure drop when multiple fixtures are running at the same time.
When incoming water pressure at a building is low, a water pressure "booster pump" may be installed on upper building floors or on a building roof to provide improved water pressure for the occupants of upper building floors.
If the incoming water pressure is from a municipal system and the building is just two or three floors high, the booster pump might be on ground level, as we described at the start of this article.
But if the incoming water pressure at a building is being provided by a well pump and water pressure tank system, and if the building is taller than three floors, the existing well pump may not be capable of delivering adequate water pressure nor adequate water floor to occupants of a fourth or higher floor.
Installing a Booster Pump for Water Pressure on the Fourth Floor of a Residential Building
Beginning on the 4th floor of such a building, install an additional pressure tank next to the second pump.
The ground floor pump will send water into the incoming pipe connection of your 4th floor pump itself.
We are assuming that your 4th floor pump will be a 1-line jet pump - that is, a single pipe connects to the pump inlet port and a single pipe connects from the pump outlet to the inlet connection of a pressure tank.
Fourth floor cold water piping should be fed by the outlet connection on the pressure tank. WATER PUMP, ONE LINE JET shows what a common 1-line jet pump looks like, and WATER PUMP, ONE LINE JET OPERATION explains how one line jet pumps work.
In our one line jet pump photo (left) the black plastic pipe coming up from lower left is attached to the pump's inlet port where an internal check valve prevents water from siphoning back out of the pump and tank into the well when the pump shuts down.
At the top right of this pump you can just make out the water connection leaving the pump where it heads up into a copper pipe.
The 4th floor pump will turn on when the pressure switch connected to its 4th floor pressure tank senses pressure dropping below the cut-in point, and it will cut "off" when the 4th floor pump has boosted pressure in your 4th floor tank up to the cutout pressure.
We expect that given that the 4th floor pump will have always at least some incoming water pressure, though low, it should be able to add additional lift t boost the 4th floor pressure as you want.
The "lift" capacity of a water pump that is a one-line jet pump is a little under 10 meters - but that's without any incoming pressure to the pump from the one located on the 1st floor.
Thanks to Ahmed Hamza for discussing this topic.
Continue reading at MUNICIPAL WATER PRESSURE IMPROVEMENTS
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Frequently Asked Questions (FAQs)
Question: to get more water pressure on higher building floors do we add a second pump or a higher-level water storage tank?
(Aug 23, 2011) Anonymous said:
I have a building that has 23 usgm requirement with 4 floors. WE installed a booster pump that supplies 28 usgpm @ 50 psi. The 3rd and 4th floor is only getting 30 psi and is not adequate to flush the toilets w/ electronic flush vales, Should I add a 2nd pump inline to boost the pressure or add a storage tank on the 4th floor and gravity feed the floors?
Anon, your question worries me that we're missing something. It's normal that if you start with 50 psi at a ground level that four floors up the pressure will be down around 30.
Question: can I run a pressure booster pump without a pressure tank?
(Oct 13, 2011) tan said:
what if i want to eliminate the pressure tank due to space requirements, what system can replace it?
Tan if there is no pressure tank at all on the system you risk short cycling and burning up your pump or pump switch as well as unsatisfactory water flow. You might, however, install a smaller tank in the same space, or you may be able to simply move the tank to elsewhere on the plumbing supply piping system. As long as the tank is located on the incoming cold supply line ahead of other plumbing components (like water heaters) you can move it elsewhere. It will mean running longer wires. You won't be installing the tank as recommended, however, if it is remote from the pressure sensing switch. Keep them together.
An exception we see is for irrigation systems whose pump and piping are designed to run continuously during the time that the irrigation or watering system is on. Some of those installations don't use a pressure tank; when the system is on the pump runs continuously.
Question: how much can a pressure booster pump increase city water pressure?
(Dec 5, 2011) Anonymous said:
Anon, if a water pressure pump is only capable of pumping to 45 psi (which sounds very odd) that means that it can not increase pressure above that amount. If the incoming water pressure is at 40 psi your pump will boost pressure to 45 psi.
In general, booster pumps use a combination of a pump, pump pressure control, and pressure tank to increase municipal water pressure by pumping pressure into the tank to a higher level than that supplied by the municipality. Typically those systems operate at on-off pressures of 20/40 or 30/50 psi, though higher pressures, up to a safe limit of about 70 psi, can be obtained from some equipment.
Where does the booster pump go?
(May 14, 2012) BRYLLE said:
(Mar 18, 2012) Ed Brown said:
our water supply comes frome a well,and this well provides water to 4 other homes also
Brylle, the booster pump is usually piped so that its output feeds both the pressure tank and the building water supply piping. You can see these connections at the typical tank tee fitting; that allows the pump to simultaneously re-pressurize the tank and deliver water to the building.
Ed: yes you can install a pressure booster pump for just your home; the pump and pressure tank are installed in your home, typically close to the point at which your community water supply enters your home. Don't forget to include a check valve on the street side of the new equipment - preventing a back-flow of water from your home into the community system should the community system pressure happen to fail.
Question: where does the check valve go in a pressure boosting system?
(Feb 1, 2014) heather hardiman said:
Heather, without details of your plumbing system I'm reluctant to risk safety or function by guessing about check valve location. You may need help from a plumber or your building department - they should be glad you asked, regardless of gender. Generally municipal water supply systems require a check valve to prevent possible back-flow from the building water piping into the municipal supply system - a SNAFU that can occur if the municipal system loses pressure. So that check valve would be installed on the street side of the booster pump.
Question: how will increasing water pipe size improve the delivery of water to our water storage tank?
(Feb 5, 2013) Said said:
Said, larger diameter water piping in general improves the flow rate of water through a building - which occupants perceive as "water pressure" improvement. But for the case you describe, increasing the pipe size for water pipes feeding your water storage tank at a building where water from the municipal source is provided only during part of each day, you would principally see that your water tank may fill a bit faster - since you are reducing the restriction between the street hook-up and the tank.
Question: what is the typical cost of a water pressure booster pump and tank system?
(June 21, 2012) Bob said:
What is the cost of an average system?
Bob, other than tripping over marketing hype or a bait-and-switch contractor there are good reasons why people are nervous about quoting a price for installing anything at a site they've never seen. I've seen a 5-minute job to replace a water heater tank pressure relief valve turn into an all-day very costly repair that made me wish we'd just bid on replacing the whole darn unit.
Question: what causes wildly-fluctuating pressure gauge readings on a booster pump system?
2/15/2014 John Tomko said:
My pressure gauge on my booster pump fluctuates wildly during pumping. I have a separate pressure gauge on my bladder tank and it operates smoothly through its range from 40 psi to 60 psi. Once the cutoff pressure at the bladder tanks is reached (60 psi) the booster pump stops running and my pressure gauge at the booster pump drops to zero. I have check valves at both the inlet and outlet of the booster pump. Check valves and pressure gauges are all new. My question is why is the booster pumps pressure gauge fluctuating wildly during pumping, and shouldn't it read around 60 psi after shutdown with the two check valves in place? Pressure gauge at booster pump is inline at an outlet tee from the pump.
John, depending on the quality and mounting location of the water pressure gauge, and further affected by the properties of the booster pump and controls in use, the indicator needle on a water pressure gauge can indeed vibrate and fluctuate like crazy while the pump is running.
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