How Does a Booster Pump Work on a Water Heater?

Steve Donaldson Master HVAC technician
Steve Donaldson
Master HVAC technician at Quality Comfort Home Services

I am Steve Donaldson, a Master HVAC technician with a rich background in addressing heating issues, especially when it comes to various types of water heaters. Leveraging my extensive expertise, I offer insights and advice to help individuals maintain a warm and secure home environment. Reach out to me at for valuable tips from a seasoned professional in the industry.

Steve Donaldson Master HVAC technician
Steve Donaldson
Master HVAC technician at Quality Comfort Home Services

I am Steve Donaldson, a Master HVAC technician with a rich background in addressing heating issues, especially when it comes to various types of water heaters. Leveraging my extensive expertise, I offer insights and advice to help individuals maintain a warm and secure home environment. Reach out to me at for valuable tips from a seasoned professional in the industry.

As a Master HVAC technician with many years of experience addressing heating issues, especially with various types of water heaters, I am often asked how booster pumps work with water heaters. In this comprehensive guide, I will explain everything you need to know about booster pump quiet, pumps and water heaters.

5 Key Takeaways on Booster Pumps and Water Heaters
  1. A booster pump is not typically used directly on a water heater. It is used to increase water pressure and flow rate in the plumbing system.
  2. A tank booster mixes cold water with hot water from the heater so less hot water needs to be drawn. This improves efficiency.
  3. Booster pumps use a motor-driven impeller to propel water from inlet to outlet. Different types of impellers are used.
  4. Key factors when selecting a booster pump are flow rate, pressure increase needed, type of facility, and noise level.
  5. Properly sized booster pumps can improve pressure and flow on upper floors, supply commercial buildings, conserve water, and support systems like reverse osmosis.

How Booster Pumps Work

A booster pump is a device used to increase the water pressure and flow rate in a building's plumbing system. The booster pump works by takes in water through an inlet valve on the suction side, then pushes it out an outlet valve on the discharge side at a higher pressure.

Booster pumps contain an impeller – a rotating component that accelerates the water using centrifugal force. The faster the impeller spins, the higher the water pressure becomes. The impeller is driven by a motor that powers its rotation.

As the water enters, the impeller spins rapidly, sucking in the water and propelling it outward powerfully from the tips of the impeller blades. This creates a high-velocity stream of pressurized water ready for use.

Common Types of Booster Pumps

water pressure booster

There are two main types of booster pumps:

  • Centrifugal pumps: These use a spinning impeller, typically with curved vanes, to accelerate water outward from the center using centrifugal force.
  • Positive displacement pumps: These use two oscillating or rotating plates to repeatedly compress an elastomeric diaphragm or set of cups to positively displace the water.

Centrifugal pumps are perhaps the most common, using a rapidly rotating impeller with blades to propel water powerfully from the tips. They are relatively affordable and provide a smooth output.

Positive displacement pumps utilize check valves and an elastomeric diaphragm instead of an impeller. As the diaphragm flexes back and forth, it draws water in and presses it out under force. These pumps provide very consistent flow regardless of pressure but tend to be more expensive.

How Booster Pumps Differ

Booster pumps can differ in the specific way they operate:

  • Single stage versus multistage: Single-stage pumps use one impeller, while multistage use two or more impellers in series to generate higher pressures.
  • Materials: Impellers and housings made from stainless steel, bronze or plastic differ in longevity and price.
  • Motor horsepower: More horsepower supports higher flow rates and pressures. Motors can be single-speed or variable-speed.
  • Impeller designs: Impellers have different vane shapes, sizes and angles that impact pumping performance.
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Proper pump selection depends on the required flow rate and pressure increase. Consulting manufacturer pump curves is recommended to match a pump to your facility's needs.

Key Specs to Consider When Selecting a Booster Pump

Choosing the right booster pump involves considering key factors:

Flow rate: The flow capacity needed in gallons per minute based on peak demand. Flow rate must be high enough for all fixtures.

Pressure increase: The amount of additional pressure needed – typical increases are 30-50 psi. Depends on incoming water pressure and the pressure desired by existing water heater.

Type of facility: Booster pumps for single-family homes differ from those for large commercial facilities.

Noise level: Quieter operation may be preferred for home or business use. Noise data should be provided.

Consulting booster pump sizing charts is recommended to pick optimal flow rate and head pressure ratings home booster pump. Oversizing the pump wastes energy, while undersizing won't fully meet water demands.

Uses and Applications of Booster Pumps

There are several typical uses and applications for booster pumps:

  • Increase water pressure to upper floors of multi-story residential buildings.
  • Provide adequate flow and pressure to commercial facilities like hotels, office buildings, schools, etc.
  • Boost pressure from private well systems.
  • Increase flow rate from city water supply lines with low pressure.
  • Conserve water by allowing the use of low-flow fixtures.
  • Support reverse osmosis drinking water systems.
  • Maintain steady pressure with varying demand in larger facilities with fluctuating flows.

For these applications, booster pumps are situated after the main water supply line to provide an extra boost. They take in lower-pressure water and output higher-pressure water for use in the building.

Booster Pumps vs. Tank Boosters for Water Heaters

Now that we've covered water booster pumps before, how do they actually relate to water heaters?

A standard booster pump is not used directly on a water heater. Rather how does booster pump work on a water heater, it pressurizes the general water supply to fixtures throughout a building.

Tank boosters, on the other hand, are devices specifically designed to work with a water heater to improve its efficiency.

A tank water heater booster that blends incoming cold water with the hot water from the water heater using thermostatic valves. This allows the tank to output higher-temperature water, which is then mixed to the desired temperature.

Benefits of tank boosters:

  • Hot water tank stores water at a higher temperature
  • Less hot water needs to be drawn for use
  • More efficient heating and energy savings
  • Faster hot water delivery

So in summary, booster pumps are for increasing water pressure and flow to the plumbing system, while tank boosters improve hot water delivery and efficiency specifically for water heaters. The two serve different roles.

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Installing and Maintaining Booster Pumps

Proper installation and maintenance are key to ensure booster pumps operate as intended. Here are best practices:


  • Install on main water supply line near water heater to boost entire plumbing system
  • Position horizontally to prevent pump cavitation from inlet starving
  • Use rigid piping with supports near inlet/outlet to reduce strain
  • Install shutoff valves before and after pump for isolation during service
  • Use flexible connectors to reduce vibration transmission
  • Verify line power matches the electrical requirements of pump motor


  • Periodically check for leaks and unusual noise/vibration
  • Confirm inlet screen is clean of debris to prevent clogging
  • Test outlet pressure and flow rate against the pump curve
  • Check amp draw on electric motor doesn't exceed the nameplate rating
  • Drain and flush the pump annually to prevent mineral deposits

This helps maximize performance and longevity of the pump. Always consult manufacturer guidelines as well during installation and maintenance.

Typical Booster Pump Issues and Solutions

Even properly installed booster pumps can develop issues over time that degrade performance. Here are some typical problems and solutions:

ProblemPossible CausesSolutions
Reduced water pressure and flow rateClogged impeller, worn impeller vanesDisassemble pump, clean out impeller, replace if excessively worn
Pump overheatingLow water flow, defective motor bearingsEnsure no blockage in water lines, test/replace bearings
Noisy operation, vibrationCavitation from low inlet pressure, misalignmentVerify adequate inlet water pressure, realign pump/piping
Insufficient pressure increaseImpeller sized wrong, motor speed issueVerify impeller size for flow rate needed, test motor and replace if necessary
Pump cycling frequentlyPressure switch malfunctionTest pressure switch and replace as needed
Pump leaking waterWorn pump sealIdentify leak location, disassemble and replace pump seal

Diagnosing the specific fault allows proper repairs to be made. Major parts like impellers, seals and motors can be serviced if needed.

Selecting a Booster Pump for Your Application

When selecting a booster pump, the key considerations are:

Type of facility – Residential home, apartment, commercial building, industrial plant etc. Larger facilities need bigger pumps.

Water pressure requirement – How much the low water pressure boost is needed? 30 psi? 50 psi? Determine the incoming and needed outgoing pressures.

Flow rate capacity – Calculate total fixture flow rates to size the pump properly. Account for peak simultaneous demand.

Single or single-stage booster pumps multi-stage – Single-stage pumps provide up to 50 psi boost, while multistage can achieve over 100 psi for tall buildings.

Horsepower rating – Horsepower must be high enough for the pressures and flow rates needed.

Impeller type – Centrifugal or positive displacement impeller designs based on performance needs.

Water type – Booster pumps for well water differ from those handling city water.

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Selecting the right pump with help from a knowledgeable supplier will ensure your pressure and flow needs are met!

Frequently Asked Questions

Below are answers to some common questions about booster pumps and water heaters:

How much pressure can a booster pump provide?

A typical residential booster pump provides between 30-50 psi of additional pressure. Large commercial and industrial pumps can generate up to 100+ psi. Pressure capabilities depend on horsepower, motor speed, and impeller design.

Where should a booster pump be located in a plumbing system?

The optimal location is on the main cold water supply line entering a building, near the water heater. This pressurizes the entire plumbing water heating system downstream.

What causes a booster pump to cycle on and off frequently?

Frequent cycling is often due to a faulty pressure switch or bladder inside the storage tank. The pressure settings may need adjustment or the components replaced.

Does a hot water booster pump provide hot water as well as cold?

Booster pumps pressurize only the cold water supply entering a building. They do not directly pump or heat hot water from a water heater.

How can I quiet a noisy booster pump?

Check for pump cavitation or any pump vibration from improper mounting. Maintaining rubber cushions between the pump and pipe connections can help reduce noise. You may need a quieter model pump.

Can I install a booster pump myself?

It is best to have a plumbing professional or pump technician install a booster pump. They have the knowledge to properly size, locate, mount, pipe and wire the booster pump selection, for optimal performance and safety.


Boosting inadequate household water pressure is a common need, especially in multi-story homes. The right water booster pump or system delivers stronger pressure and ample flow rate for all your water needs.

Centrifugal and positive displacement pumps use impellers and oscillating diaphragms to increase pressure from the main supply line. Consider factors like flow rate, pressure rise, and noise when selecting a pump.

Proper sizing, installation and maintenance keeps water pressure booster pumps performing their essential role – providing reliable water pressure throughout your building. If you have any other questions, don't hesitate to contact me!

Steve Donaldson Master HVAC technician
Steve DonaldsonMaster HVAC technician at Quality Comfort Home Services

I am Steve Donaldson, a Master HVAC technician with a rich background in addressing heating issues, especially when it comes to various types of water heaters. Leveraging my extensive expertise, I offer insights and advice to help individuals maintain a warm and secure home environment. Reach out to me at for valuable tips from a seasoned professional in the industry.

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