Self acting HIUs with integral bypass control

Danfoss’s self acting IHPT controller technology is at the heart of FlatStation DHW generation.

The IHPT is a self acting pressure and temperature controller with integral bypass control.

This design approach to HIU controls ensures optimum reaction times, long operating life and no requirement for electrical power supply.


Jan Hansen“Good hydronic control is the cornerstone of lean heat networks!”

Jan Hansen



issue45-image-3Danfoss IHPT bypass control

The HIU bypass fulfills an important role in heat networks.

Instantaneous DHW comfort

The IHPT manages the bypass to ensure that DHW generation is instantaneous on demand, for optimum comfort and minimum water wastage.

Primed 8ºC temperature set-back

When demand ceases, to minimise HIU / pipe distribution heat losses and to keep system return temperatures as low as possible, the controller drops the temperature of the plate heat exchanger by 8ºC.

Dropping the temperature by 8ºC does not noticeably compromise reaction times.


Circulation of chemicals in heat networks

BSRIA BG 50/2013 (p. 5) states: 

issue45-image-4“It is essential to avoid prolonged stagnation in heating and cooling systems. Stagnation will allow the sedimentation of suspended solids and promote the formation of biofilms, increasing the risk of microbially influenced corrosion. Also, most inhibitors work more effectively under flowing rather than stagnant water conditions. The system control strategy should therefore ensure that circulation pumps and control valves are periodically operated to reduce the risk of stagnation and ensure full distribution of all water treatment chemicals.

Heat Networks: Code of Practice for the UK

issue45-image-5“The use of bypasses shall be minimised – where instantaneous heat exchangers are used, the standby flow will normally result in a sufficient bypass flow. Fixed bypasses shall not be used and any bypasses shall be temperature controlled so that the bypass only operates when flow temperatures are below a minimum set point.”


IHPT – Designed with self-acting control to achieve the fastest possible reaction times

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IHPT tapping performance

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Danfoss – Long lasting quality to the core

System reliability, building and occupant safety are crucial when it comes to district heating and cooling applications. This is why we give special attention to design and material selection used in our products. Valve bodies are made of high quality red bronze and cast iron or steel. Critical internal parts are made from well-proven stainless steel 1.4404 /1.4571 /1.4021. In combination with a specially designed valve seat and cone, this ensures resistance to cavitation and corrosion. Danfoss products will ensure trouble-free operation, low maintenance and operational costs.

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About Danfoss

For more than 75 years Danfoss has been supplying innovative heating solutions that cover everything from individual components to complete district heating systems. Danfoss engineers technologies that enable the world of tomorrow to do more with less. We employ 24,000 people and serve customers in more than 100 countries. Driven by our customers’ needs, we build on years of experience to be at the forefront of innovation, continually supplying components, expertise and complete systems for climate and energy applications.

Today, our advanced, reliable and user-friendly technology helps to keep people comfortable and companies competitive across the world.

We play an active role in the main growth themes in a world that is rapidly changing: infrastructure, food, energy and climate are the focus of our business. Cities for millions that touch the sky. A richer harvest to feed a growing world. Keeping food fresh and our children warm in a world that can make more out of less.

This is how we are Engineering Tomorrow.


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