critical cactusMoonshan Hot Water Circulator Pump is our pick for the Best Hydronic Heating Boiler component because its 304 stainless steel construction provides superior corrosion resistance compared to standard cast iron alternatives.
Selecting the right components for a hydronic system requires balancing flow capacity with the specific pressure requirements of your home's loop. Whether you are upgrading a circulation pump or replacing a pressure regulator, the primary goal is ensuring consistent heat distribution while minimizing the risk of leaks or air pockets that can degrade performance over time.
Experienced installers prioritize parts that simplify maintenance, such as cartridge-style pumps or valves with easy-service access. By focusing on durable materials and compatible hardware, you can extend the service life of your boiler setup and maintain steady, quiet operation throughout the heating season.
When planning a full system overhaul, it is helpful to review the Best Hot Water Heating Systems for Homes to understand how these individual components integrate into a complete setup.
10 Best Hydronic Heating Boiler in 2026 Reviews
Quick Comparison
| Product | Best For | Key Strength | Score |
|---|---|---|---|
| Moonshan Hot Water Circulator Pump | Best Overall | Premium 304 stainless steel construction resists corrosion and rust. | 4.9 |
| Sezhylauo Hot Water Circulation Pump | High-Head Performance for Closed Loops | 3-speed adjustable motor for optimized flow and energy efficiency. | 4.9 |
| Zezhimi Boiler Feed Pressure Regulator | Maintains Precise System Pressure | Adjustable pressure settings for precise system customization. | 4.6 |
| AB Plate Heat Exchanger | Efficient Thermal Transfer Solution | High thermal efficiency provided by 30 brazed 316L stainless steel plates. | 4.6 |
| GuardFlow Zone Valve Power Head | Silent Control for Multi-Zone Systems | Silent, vibration-free operation via a heat-responsive wax element. | 4.5 |
| ISHARINGAUTOPARTS Magnetic Boiler Filter | Captures Sludge and Debris | Dual isolation valves allow for maintenance without full system shutdown. | 4.8 |
| Midline Valve Boiler Air Scoop | Continuously Purges Trapped Air | Continuous air separation reduces the need for manual venting. | 4.6 |
| Star Brite Boiler System Antifreeze | Prevents Freezing in Hydronic Lines | Provides burst protection down to -100°F for extreme climate reliability. | 4.4 |
| Truma Alde Glycol Transfer Fluid | Protects Aluminum Heating Components | Corrosion inhibitor package specifically formulated for aluminum heat exchangers. | 4.8 |
| LawnKissL Hydronic Expansion Tank | Manages Thermal Pressure Fluctuations | Pre-charged to 12 PSI for immediate installation readiness. | 4.4 |
How We Chose
Evaluating components for a hydronic heating boiler involves analyzing build quality, material longevity, and system integration. We focus on how specific parts like circulators, valves, and filters impact the overall efficiency and reliability of a closed-loop system, prioritizing hardware that offers straightforward installation and long-term protection against common issues like sludge buildup and pressure fluctuations.
- Material durability and corrosion resistance
- Compatibility with standard boiler and piping configurations
- Ease of maintenance and component replacement
- Operational noise levels and energy efficiency
- Precision of pressure regulation and flow control
1 Moonshan Hot Water Circulator Pump — Boosts Flow in Hydronic Loops
Maintaining consistent water circulation is essential for the efficiency of any residential heating system, and the Moonshan 110V Hot Water Recirculating Pump is engineered to address this need directly. Constructed with a premium 304 stainless steel pump head, this unit offers superior resistance to rust and corrosion compared to standard cast iron alternatives, making it a robust choice for long-term integration into hydronic loops.
This circulator pump features 3-speed adjustment settings (46W, 85W, and 100W), allowing users to tailor the power output to the specific demands of their boiler or radiant heating setup. With a maximum flow capacity of 13 GPM and a 26-foot head, it provides the necessary pressure to ensure hot water reaches faucets quickly, effectively reducing water waste and wait times.
Designed for versatility, the system is compatible with a wide range of setups, including standard water heaters, solar systems, and hydronic radiant heating. The maintenance-free construction eliminates the need for seal replacements, while the included all-in-one installation kit—featuring 1" FNPT flanges, gaskets, nuts, and bolts—streamlines the setup process by providing all necessary hardware in a single package.
The pump is built to operate under demanding conditions, with the ability to withstand temperatures up to 230°F and pressures reaching 1.0 MPA. Its quiet operation and compact dimensions make it a practical addition to residential plumbing configurations where space and noise control are priorities.
Best for: Homeowners looking for a durable, stainless steel circulator pump to improve flow and reduce wait times in hydronic heating or domestic hot water systems.
Skip if: Users requiring a high-capacity industrial pump for large-scale commercial applications or those needing a pump with specialized smart-home connectivity features.
- Premium 304 stainless steel construction resists corrosion and rust.
- 3-speed power adjustment allows for flexible system matching.
- Complete installation kit included with all necessary hardware.
- Maintenance-free design requires no seal replacements.
- Manual speed adjustment requires physical access to the unit.
2 Sezhylauo Hot Water Circulation Pump — High-Head Performance for Closed Loops
Maintaining consistent flow in a hydronic heating system requires a reliable circulator, and the Sezhylauo Hot Water Circulation Pump is engineered to handle high-head, medium-flow demands. This unit is designed as a direct replacement for Bell & Gossett NRF-36 pumps, providing a straightforward solution for residential heating and hot water recirculation loops.
The pump features a 3-speed motor that allows for adjustable performance based on system requirements. At its highest setting, it consumes 270W and 2.3A, while the lower settings offer reduced power consumption of 180W/1.6A and 130W/1.2A. This flexibility helps balance energy efficiency with the specific pressure needs of your piping layout.
Constructed with a heavy-duty cast iron housing, the pump is built for continuous operation in closed-loop systems. It supports a maximum pressure of 150 PSI and a maximum head of 34 feet, making it suitable for demanding hydronic applications. The flanged connection design accommodates multiple pipe sizes, including 3/4", 1", 1-1/4", and 1-1/2", providing versatility during installation.
Maintenance is simplified through the cartridge-style assembly, which houses all moving parts. This design allows for quick replacement of internal components without the need to remove the entire pump housing from the plumbing, minimizing system downtime. The unit is engineered for low-noise operation, ensuring it functions discreetly within a home environment.
Best for: Homeowners or technicians seeking a direct, high-head replacement pump for existing Bell & Gossett NRF-36 hydronic heating systems.
Skip if: Users requiring a stainless steel housing for open-loop potable water systems, as this model is constructed from cast iron.
- 3-speed adjustable motor for optimized flow and energy efficiency.
- Cartridge-style design allows for easy internal component replacement.
- High-head performance capable of handling 34 ft of lift.
- Broad compatibility with standard flanged pipe sizes from 3/4" to 1-1/2".
- Cast iron construction is not suitable for open-loop potable water systems.
- Manual speed adjustment requires physical access to the pump settings.
3 Zezhimi Boiler Feed Pressure Regulator — Maintains Precise System Pressure
Maintaining consistent pressure within a hydronic heating system is essential for efficient operation, and the Zezhimi Boiler Feed Pressure Regulator provides a reliable solution for this task. Designed as a direct replacement for the S1156F, this component ensures your boiler remains properly filled and pressurized, even when minor system leaks occur.
The unit features an adjustable pressure setting, allowing you to calibrate the valve to meet the specific requirements of your heating system. This precision helps maintain optimal performance across various residential and commercial setups. The inclusion of a fast fill lever simplifies the process of purging air from the system, significantly reducing the time and effort required for routine maintenance.
Built for longevity, the regulator utilizes a robust brass and bronze body that resists the wear associated with demanding environments. An integrated stainless steel strainer further protects internal mechanisms from debris, ensuring consistent water flow. The design also incorporates a tight-seating check valve to prevent backflow and leaks, enhancing the overall safety and reliability of your hydronic infrastructure.
While this regulator is engineered for durability and ease of use, it is specifically designed for systems utilizing a 1/2-inch connection. Its compact dimensions make it suitable for tight installations, though users should confirm their existing piping size before integration to ensure a proper fit.
Best for: Homeowners and technicians needing a high-capacity, adjustable replacement valve for 1/2-inch hydronic boiler feed lines.
Skip if: Users with systems requiring non-standard pipe diameters or those seeking a non-adjustable, factory-preset regulator.
- Adjustable pressure settings for precise system customization.
- Fast fill lever for simplified maintenance and air purging.
- Durable brass and bronze construction with stainless steel strainer.
- Tight-seating check valve prevents backflow and leaks.
- Fixed 1/2-inch size limits compatibility with larger or smaller piping systems.
4 AB Plate Heat Exchanger — Efficient Thermal Transfer Solution
Efficient thermal management is essential for maintaining consistent temperatures in hydronic systems, and the AB Plate Heat Exchanger provides a robust solution for these demanding applications. By utilizing 316L stainless steel plates brazed with 99.9% copper, this unit is engineered to withstand high pressure and temperature environments while ensuring reliable heat transfer.
The AB Plate Heat Exchanger features a compact, lightweight design that simplifies installation in tight spaces, such as mechanical rooms or near wood boilers. With a capacity ranging from 250,000 to 330,000 BTU per hour, it is capable of handling significant thermal loads across various setups, including floor heating, snow melting, and domestic water heating systems.
Designed for versatility, the unit includes smooth threads for flexible, quick hookups, allowing for integration into existing hydronic or solar heating loops. Because it operates without electricity or oxygen consumption, it serves as an energy-efficient component for zone heating and radiator systems, providing a durable, integral piece that resists leakage.
This heat exchanger is UL certified, reflecting a focus on manufacturing quality. Whether utilized for hydraulic oil cooling or as part of a district heating system, the AB Plate Heat Exchanger offers high thermal efficiency in a small footprint, backed by technical support for installation guidance.
Best for: This heat exchanger is best for residential or light commercial hydronic heating, snow melting, and wood boiler systems requiring efficient, compact thermal transfer.
Skip if: Skip this model if your application requires a larger capacity than 330,000 BTU or if you need a non-brazed, cleanable plate design for high-fouling fluids.
- High thermal efficiency provided by 30 brazed 316L stainless steel plates.
- Compact and lightweight design allows for flexible installation in tight spaces.
- Durable construction capable of withstanding high pressure and temperature.
- Energy-efficient operation as it requires no electricity to facilitate heat transfer.
- Brazed design cannot be disassembled for manual cleaning of the internal plates.
- Fixed capacity range may be insufficient for very large-scale industrial heating requirements.
5 GuardFlow Zone Valve Power Head — Silent Control for Multi-Zone Systems
Maintaining consistent temperatures across a multi-zone hydronic system often hinges on the reliability of the valve actuators. The GuardFlow Zone Valve Power Head utilizes a heat-responsive wax element rather than a traditional motor, providing a silent, vibration-free method for opening and closing valves within your heating circuit.
This replacement unit is engineered specifically for compatibility with Taco 556 and 570 series zone valves, allowing for a targeted repair rather than a full system overhaul. The thermal-actuated design drives an internal piston to manage flow, which helps minimize mechanical wear and contributes to long-term operational stability. It is constructed with an aluminum alloy housing for corrosion resistance and is rated for performance in temperatures ranging from 40°F to 240°F.
Installation is designed to be straightforward for those familiar with basic boiler controls. The process involves a standard three-wire connection and operates on 24 VAC, making it a practical choice for restoring zone control. Because it is a direct replacement for existing Taco sweat valve assemblies—ranging from 1/2" to 1-1/4"—it avoids the labor-intensive requirements of plumbing modifications.
By focusing on a heat-responsive wax element instead of motor-driven gears, this power head provides a reliable alternative for balancing hydronic zones. It has been tested through more than 50,000 heating cycles to ensure consistent performance, offering a cost-effective way to maintain precise control over your home or commercial heating environment.
Best for: Homeowners and technicians needing a direct, silent replacement for faulty Taco 556 or 570 series zone valve actuators.
Skip if: Users requiring a motor-driven actuator or those with valve systems outside of the specified Taco 556 and 570 series compatibility range.
- Silent, vibration-free operation via a heat-responsive wax element.
- Direct compatibility with Taco 556 and 570 series zone valves.
- Corrosion-resistant aluminum alloy housing construction.
- DIY-friendly installation requiring no specialized plumbing tools.
- Limited compatibility restricted specifically to Taco 556 and 570 series valve bodies.
- Thermal-actuated design may have different response times compared to traditional motor-driven actuators.
6 ISHARINGAUTOPARTS Magnetic Boiler Filter — Captures Sludge and Debris
Maintaining the longevity of a hydronic heating system often hinges on preventing the accumulation of magnetite and rust within the loop. The ISHARINGAUTOPARTS Magnetic Boiler Filter addresses this by utilizing a high-strength magnetic core to capture ferrous particles and sludge before they can damage sensitive components like pumps, valves, and radiators.
Designed for seamless integration, this filter features a professional-grade DN20 3/4-inch threaded connection. Its construction utilizes industrial-grade, heat-resistant materials to ensure reliability under the continuous demands of a closed-loop heating environment. The unit is engineered to support system efficiency by reducing the risk of clogs that typically lead to costly maintenance.
Usability is a primary focus, highlighted by a design that allows for quick and easy maintenance. The inclusion of dual isolation valves enables users to service the unit without shutting down the entire heating system or removing the filter from the pipeline. Contaminants can be discharged through the bottom drain valve, while the magnetic core is easily removed from the top for inspection and cleaning.
For optimal performance, the unit requires correct orientation during installation, guided by flow direction arrows on the housing. While it provides a robust solution for magnetic particle separation, users should ensure their system plumbing is compatible with the 3/4-inch connection size to avoid the need for additional adapters.
Best for: Homeowners and HVAC technicians seeking to protect hydronic heating components from sludge and magnetite buildup.
Skip if: Users with piping systems that do not utilize a 3/4-inch (DN20) connection size or those requiring a non-magnetic filtration solution.
- Dual isolation valves allow for maintenance without full system shutdown.
- Magnetic core effectively captures ferrous debris and magnetite.
- Industrial-grade, heat-resistant construction ensures long-term durability.
- Easy-access design simplifies the removal of captured contaminants.
- Requires specific 3/4-inch plumbing for direct installation.
- Manual cleaning of the magnetic core is necessary for ongoing performance.
7 Midline Valve Boiler Air Scoop — Continuously Purges Trapped Air
Maintaining a consistent, air-free environment is essential for the efficiency of any hydronic heating system, and the Midline Valve S1556 Boiler Air Scoop is designed to address this by continuously separating and purging trapped air. By automating the removal of air bubbles that can impede circulation, this component helps ensure that your boiler operates without the frequent need for manual venting.
Constructed from heavy-duty, one-piece cast iron, this air scoop is built for durability and resistance to both rust and corrosion. Its lead-free composition makes it a suitable choice for various residential heating setups, providing a robust solution for those looking to upgrade or replace an existing air separator.
The unit features standard 3/4 in. FIP connections, which are engineered to provide a secure, leak-free fit. This universal design allows it to integrate seamlessly with most major boiler brands and standard piping, vents, or expansion tanks, simplifying the installation process for those performing routine system maintenance.
While this valve is a straightforward solution for air management, it is important to verify your system's pipe diameter and connection type before installation. Because it is a specialized component for hydronic loops, it is best suited for users who have confirmed their system requires a 3/4-inch FIP interface for air separation.
Best for: Homeowners and technicians looking for a durable, cast-iron solution to continuously purge air from a hydronic heating system with 3/4-inch piping.
Skip if: You require a different connection size, such as 1-inch or 1/2-inch, or if your specific boiler system design necessitates a different type of air management device.
- Continuous air separation reduces the need for manual venting.
- Heavy-duty cast iron construction ensures long-term durability.
- Universal compatibility with most major boiler brands.
- Secure, leak-free 3/4-inch FIP connections.
- Fixed connection size limits use to 3/4-inch piping systems.
- Cast iron weight may require additional support during installation compared to lighter materials.
8 Star Brite Boiler System Antifreeze — Prevents Freezing in Hydronic Lines
Maintaining the integrity of hydronic heating systems requires specialized fluids designed to withstand extreme temperature fluctuations. The STAR BRITE Premium -100° Boiler System Antifreeze is engineered to provide robust burst protection down to -100°F (-73°C), ensuring that critical lines remain operational even in severe cold environments.
This propylene glycol-based fluid is specifically formulated for superior heat transfer, making it a reliable choice for complex hydronic setups such as Aqua-Hot and Hydro-Hot systems. By utilizing an ethanol-free composition, the formula supports the long-term efficiency of internal components, preventing the degradation often associated with harsher chemical alternatives.
Beyond its primary function as a thermal transfer medium, the antifreeze includes premium corrosion inhibitors. These additives are essential for protecting the internal surfaces of traditional boilers, closed-loop systems, and solar thermal arrays from oxidation and scale buildup, which can otherwise impede system performance over time.
As an environmentally better solution, this product offers a more conscious option for maintenance professionals and homeowners alike. The STAR BRITE Premium -100° Boiler System Antifreeze is manufactured in the United States, providing a consistent, quality-assured fluid for those seeking to maintain their heating and cooling infrastructure with professional-grade materials.
Best for: Owners of hydronic heating systems like Aqua-Hot or Hydro-Hot who require high-performance, corrosion-inhibiting antifreeze for extreme cold climate protection.
Skip if: Users seeking a non-glycol based solution or those with systems specifically requiring a different chemical composition as dictated by the manufacturer's manual.
- Provides burst protection down to -100°F for extreme climate reliability.
- Contains premium corrosion inhibitors to extend the lifespan of internal system components.
- Ethanol-free formula ensures high efficiency and system longevity.
- Optimized for superior heat transfer in specialized hydronic systems.
- Requires proper dilution or full-strength application based on specific system requirements.
- Heavier 9.5-pound weight per gallon may require careful handling during system filling.
9 Truma Alde Glycol Transfer Fluid — Protects Aluminum Heating Components
Maintaining the integrity of an aluminum hydronic heating system requires specialized chemistry, and the Truma Alde Glycol Heat Transfer Fluid is engineered specifically for this purpose. Unlike generic automotive coolants, this ethylene glycol-based formula contains a dedicated corrosion inhibitor package designed to prevent the pitting and scale buildup that can compromise aluminum heat exchangers over time.
This ready-to-use 1 gallon fill eliminates the need for manual dilution, allowing for a straightforward top-off or a complete system flush. The fluid is easily identified by its signature blue-green color, which serves as a visual confirmation that the correct, manufacturer-approved chemistry is being introduced into the boiler loop.
Beyond its primary role in corrosion prevention, the fluid provides reliable all-weather heat transfer performance. It remains effective across a broad temperature range, ensuring the system is protected against freeze damage during cold-weather travel or extended periods of off-season storage.
For owners performing their own maintenance, using this genuine fluid is essential for keeping the heating system's warranty intact. Because it is formulated for compatibility with Airstream, T@B, and other campers utilizing Alde boilers, it avoids the risks associated with mixing incompatible inhibitor packages found in standard antifreeze.
Best for: Owners of campers with Alde aluminum hydronic heating systems who need to perform routine fluid maintenance or top-offs with manufacturer-approved chemistry.
Skip if: You are looking for a universal automotive coolant, as this product is specifically formulated for the unique metallurgy of Alde aluminum heating systems.
- Corrosion inhibitor package specifically formulated for aluminum heat exchangers.
- Ready-to-use formula requires no premixing or dilution.
- Protects against freeze damage during storage and cold-weather use.
- Maintains system warranty compliance by using genuine OEM fluid.
- Not compatible with non-Alde or non-aluminum heating systems.
- Requires periodic replacement every two years to maintain inhibitor effectiveness.
10 LawnKissL Hydronic Expansion Tank — Manages Thermal Pressure Fluctuations
Maintaining consistent pressure within a home heating system is essential for longevity and efficiency. The LawnKissL Hydronic Expansion Tank is a specialized component designed to manage the pressure fluctuations that occur naturally during thermal expansion in residential boilers and hydronic loops.
This compact 2-gallon expansion tank serves as a critical buffer, preventing excessive pressure buildup that can stress system components. It arrives pre-charged to 12 PSI, allowing for straightforward integration into existing setups. The unit features a durable steel shell paired with a resilient butyl diaphragm, materials chosen to withstand the rigors of continuous heating cycles.
Installation is facilitated by a standard ½" NPT inlet/outlet, ensuring compatibility with a wide range of residential plumbing configurations. With a maximum working pressure of 100 PSI, this tank is engineered to handle the operational demands of standard home boilers and solar heating systems. Its design specifically supports Amtrol Extrol residential boilers, making it a direct-fit solution for those maintenance tasks.
Choosing the right expansion tank requires verifying your system's specific pressure requirements and space constraints. While this model offers robust construction and reliable pressure management, users should ensure their current system architecture aligns with the 2-gallon capacity and NPT connection type before installation.
Best for: Homeowners and technicians needing a reliable, compact replacement expansion tank for residential hydronic heating or solar systems.
Skip if: Systems requiring a larger capacity tank or those utilizing different connection sizes or non-standard pressure requirements.
- Pre-charged to 12 PSI for immediate installation readiness.
- Durable steel shell and butyl diaphragm construction.
- Compact 2-gallon size fits easily into residential utility spaces.
- Standard ½" NPT inlet/outlet for broad compatibility.
- Fixed 2-gallon capacity may be insufficient for larger hydronic systems.
Best Hydronic Heating Boiler Buying Guide
Material Selection for Longevity
The materials used in your boiler components directly impact their lifespan. Stainless steel is often preferred for pump heads and internal components because it resists the rust and corrosion that can occur in water-based heating systems over years of continuous operation.
Conversely, cast iron remains a standard for heavy-duty applications where structural rigidity is paramount. When choosing between these, consider the water chemistry of your system and whether you are using additives that might react with specific metals over time.
Understanding Flow and Head Pressure
A circulator pump must be matched to the specific head pressure and flow requirements of your piping layout. If a pump is undersized, the furthest radiators or zones may not receive adequate heat, while an oversized pump can lead to excessive noise and energy waste.
Always check the GPM (gallons per minute) and maximum head specifications against your system's design. Adjusting the speed settings on a multi-speed pump allows for fine-tuning performance to match the actual resistance of your heating loops.
Pressure Management and Safety
Maintaining correct system pressure is essential for boiler safety and efficiency. A high-quality pressure regulator ensures that the system stays within its operating range, automatically filling the loop as needed while preventing backflow.
Expansion tanks work in tandem with these regulators to absorb the volume changes that occur as water heats and cools. Without a properly sized expansion tank, pressure spikes can trigger relief valves, leading to water loss and potential system damage.
Maintaining System Cleanliness
Sludge and magnetite buildup are common enemies of hydronic systems, often causing blockages in valves and reducing heat transfer efficiency. Installing a magnetic filter can capture these ferrous particles before they reach sensitive components like pumps and heat exchangers.
Routine maintenance, such as cleaning the magnetic core or purging air from the system, is significantly easier when you have accessible isolation valves. Using an air scoop or separator further ensures that trapped air does not cause noise or circulation issues.
Compatibility and Replacement Strategy
When replacing parts, verify that the new component is compatible with your existing boiler model and piping size. Many modern replacements are designed to fit standard flange configurations, which simplifies the installation process and reduces the need for custom plumbing.
Consider the long-term availability of replacement parts for your specific boiler brand. Choosing modular components, such as zone valve power heads that can be replaced without removing the entire valve body, saves significant time and labor during future repairs.
Frequently Asked Questions
How often should I check my boiler's pressure regulator?
It is advisable to inspect your pressure regulator annually, typically before the start of the heating season, to ensure it maintains the correct pressure and shows no signs of leaking.
Can I mix different types of glycol in my boiler system?
No, you should never mix different types or brands of glycol. Different formulations have specific corrosion inhibitors that may react negatively when combined, potentially damaging your boiler's heat exchanger.
Why is my hydronic system making a gurgling noise?
Gurgling noises usually indicate trapped air in the lines. An air scoop or manual vent should be used to purge the system, ensuring water flows freely without air pockets.
What is the benefit of a magnetic boiler filter?
A magnetic filter captures rust particles and sludge circulating in the water, preventing these contaminants from clogging valves, damaging pump impellers, and reducing the efficiency of your radiators.
Do I need to replace the entire zone valve if the head fails?
Not necessarily. Many modern zone valves feature replaceable power heads, allowing you to swap out the actuator without draining the system or removing the valve body from the pipes.
Conclusion: Our Top Pick
Our top pick is Moonshan Hot Water Circulator Pump. Selecting the right components for your hydronic heating system is a matter of matching technical specifications to your home's specific layout. By prioritizing durable materials like stainless steel and ensuring that pumps and regulators are correctly sized, you can maintain a reliable and efficient heating environment for years to come.
Regular maintenance remains the most effective way to protect your investment. Whether you are installing a magnetic filter to prevent sludge or replacing a worn valve head, focusing on compatible, high-quality parts will minimize downtime and keep your system operating at its peak performance level.