"I would estimate over the length of this project, I have spent 50% less time designing than I would on our previous software.

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CASE STUDIES Award-Winning Heating Design "Using h2x was pivotal, allowing for precise heat loss calculations, pipe sizing and flow rates for each room. This level of detail ensured that the heating load accurately matched each space's requirements, minimising energy waste and maximising comfort. The strategic placement of heat pumps and careful sizing of pipework were crucial in maintaining minimal pressure drops over an 18-metre distance." Read the full case study

The maximum allowable pressure is the peak pressure that a system can safely tolerate without causing damage to its components or risking a system failure.

Remember, this is just a rule of thumb. In addition to water heater volume, an engineer will consider other factors when sizing and selecting a thermal expansion tank, such as entering and leaving water temperatures and minimum and maximum pressures. The expansion volume may then be calculated and a tank selected based on acceptance volume and overall volume. In most cases, the engineered expansion tank size will be smaller than the 10% of the water heater volume, but, for budgeting/planning purposes, this estimate will get you in the right ballpark.

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The strategic placement of heat pumps and careful sizing of pipework were crucial in maintaining minimal pressure drops over an 18-metre distance."

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CASE STUDIES Greengate, UK "I would estimate over the length of this project, I have spent 50% less time designing than I would on our previous software. The ability to output the design straight into Revit assisted clash detection and coordination." Read the full case study

If you have questions about equipment size, water heaters or expansion tanks, you should talk to your manufacturing representative to ensure that you’re selecting the best equipment sized correctly for your application.

CASE STUDIES Salon Republic, USA "The quality of the designs saw significant improvement with the adoption of h2x." "The software offers precision through detailed result outputs and advanced options for efficient pipe sizing, allowing heating engineers to optimise based on parameters like maximum velocity and pressure drop." Read the full case study

Gain a comprehensive understanding of expansion vessels inside this informative blog. Includes a calculation example for practical insights.

– Incorrect positioning: this can disrupt the vessel’s primary function of accommodating fluid volume changes, potentially leading to dangerous pressure build-ups or operational inefficiencies.

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To protect the water heater, pipes, and other system components from excessive pressure when heating water, an expansion tank is added. A simple device, it is nothing more than a tank with a bladder (thick balloon) inside. The space between the bladder and the inner wall of the tank is pre-charged with air to closely match the neutral pressure of the system BEFORE the water is heated. Then, when heat is applied and the pressure goes up, the expanded water volume flows inside the bladder. The air outside the bladder compresses against the tank walls, providing the cushion needed to protect the rest of the system.

As a rule of thumb, a thermal expansion tank should be about 10% of the total water heater volume. Let’s take some examples:

The expansion vessel provides the necessary ‘give’ in the system to handle this extra volume, preventing potential over-pressurisation damage.

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Consider a system with a water volume of 500L, an initial temperature (T_initial) of 10°C, and a maximum operating temperature (T_max) of 80°C.

The critical process of accurately calculating and correctly positioning an expansion vessel is crucial in designing and operating heating and cooling systems.

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With the right software, like h2x Engineering’s Heating Design Software, you can drive efficiency and accuracy in your heating system projects.

"The software offers precision through detailed result outputs and advanced options for efficient pipe sizing, allowing heating engineers to optimise based on parameters like maximum velocity and pressure drop."

Embracing the digital revolution in the form of heating design software, like that offered by h2x Engineering, is crucial for professionals who wish to stay competitive in the industry.

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3 bar (300 kPa / 43.5 psi) is commonly used for this (recommended by CIBSE) but the manufacturer’s documentation is typically the best source for this information.

Having understood the crucial parameters, we now venture into the specifics of calculating the size of an expansion vessel.

Expansion vessels are required in systems where a closed circuit is subjected to a fluctuation in temperature e.g. heating and cooling systems.

An expansion vessel, or expansion tank, is a device in a heating or cooling system that accommodates the extra volume of water produced when the system water is heated or cooled.

This data can usually be found within the system’s design specifications. In cases where it’s not readily available, a pressure gauge might be needed to measure this pressure.

These vital components, also known as expansion tanks, are pivotal in maintaining system safety and operational efficiency.

As the water heats up, it expands, and without a place to go, this increase in volume can cause a dramatic rise in pressure.

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Wattspotable Water Expansion tank

David Swinson has worked for Heat Transfer Sales for over 35 years. His knowledge of HVAC and plumbing equipment is vast.

This number will vary based on your geographical location and the associated climate but will likely be around 5°C (41°F) in the winter months.

The transformation of industries by the digital revolution is a story told many times over, and heating system design is no exception.

Moreover, to avoid the issue of pump cavitation, installing the vessel on the suction side of the recirculation pump is recommended.

We are proponents of sustainable and efficient hydronic heating and cooling building solutions, which are at the heart of commercial green building.

This level of detail ensured that the heating load accurately matched each space's requirements, minimising energy waste and maximising comfort.

Ideally, they should be placed in a cooler section of the system, for instance, the return pipe close to the boiler or chiller.

They counterbalance changes in fluid volume, and consequently pressure fluctuations, which occur due to variations in temperature.

When you look a water heater in a large building or even a home, you may notice a much smaller tank close by. That small tank is a thermal expansion tank. An expansion tank in this application is a vessel design to accept additional system volume resulting from heating water. Water is incompressible and, when it is heated, it expands. If this happens in a system with a fixed volume of pipes and equipment, you will quickly discover the weakest point in the system as water begins to spray through it. (Hopefully, it is the pressure relief valve releasing water!)