Knowledge
Technical articles
Working notes from 25 years of designing, building and servicing heat network equipment. For heat network KPIs and the standards behind them, see hnqap.org.
60-16 Heat Networks
The BESA test shows how an HIU can achieve an annual average return temperature of 16°C. This was with keep-warm turned
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AB-QM Control Valves
The AB-QM Pressure Independent Control Valve has been used by Thermal Integration for many years now as a reliable means to control flow
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Anti Legionella Function
After 24 hours of inactivity, the HIU will bring the domestic hot water plate heat exchanger up to temperature to prevent legionella from growing. The…
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Balancing of Central Heating Systems
The job of balancing radiators properly appears to have become a dark and forgotten art, despite the fact it remains the key to an efficient system.…
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BESA HIU Tests
Anybody can say they are Number 1, depending on how you dress it
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Buffer Logic
The four lines represent sensor readings from temperature sensors in a buffer store at regular distances apart. It is an example of a properly controlled…
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CHP Designs
This article is dedicated to systems making use of a CHP Combined Heat and Power
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Communal Heating and Central Heating
This article is aimed at describing the methods of feeding central heating in properties connected to district heating, and in particular the decision to…
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Communal Heating and CO2 Air Source Heat Pumps
This is an article dedicated to the very specific task of driving services to a block of flats using air source heat pumps and a heat network as
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Communal Heating and Heat Pumps
This article is a study of how to implement district heating using Heat
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Communal Heating and Hot Water Cylinders
This article was started in response to an email thread we found most interesting, and helps solidify a number of the questions around designing a heat…
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Communal Heating and Hydrogen
This is seen in the graph below looking at real loads for 2020. The Blue DHW and Orange CH low are driven by the heat pumps. The Green is delivered by…
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Communal Heating Design
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Connected Systems
Its now possible to do pretty much whatever you want when it comes to metering, monitoring, and home control,
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Connecting to an S-Plan or Y-Plan system
It is possible to connect a pellet boiler to a standard S-Plan or Y-Plan arrangement, with respectively either a motorised valve for hot water and a…
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CP1 Compliance
This article covers the process of handing over a development fitted with HIUs to CP1
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Danfoss RA-DV Radiator Valves
This article describes the standard kit supplied with Danfoss RA-DV radiator
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Danfoss SonoSelect-Safe
The Danfoss SonoSelect 10 and SonoSafe 10 are ultrasonic compact energy meters intended for measuring energy consumption in heating, cooling and combined…
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DHW Duration
The following chart shows the duration of hot water outlet use, by
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DHW Recirculation Pump Option
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Diehl SHARKY 774
SHARKY 774 COMPACT ultrasonic energy meter is designed for measuring the energy consumption in heating or bifunctional heating/cooling application for…
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Diehl SHARKY 775
SHARKY 775 is a ultrasonic compact energy meter designed for measuring the energy consumption in heating and bifunctional heating/cooling application, for…
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Distributed Communal Heating
Distributed, or De-Centralised, District Heating has a number of
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Diversity
Diversity is how one works out the peak instantaneous hot water load on a heat network, based on the number of properties. As the number increases, the…
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DP Buffering and Pump Control
As the design and quality of heat networks improves, we are starting to see system flow rates drop, as unnecessary bypass flows are eliminated, and we are…
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Economy and Comfort Mode Functionality
It is common for HIU's to include a thermostatic bypass to maintain heat across the domestic hot water plate heat exchanger at all times, this helps…
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EMBED
The Energy Saving Trust’s EMBED hub is an interactive online resource of building energy performance data, collated from energy monitoring field trials…
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Ethernet Switch
The ESW500 range of Industrial Managed Ethernet Switches establish Ethernet network connections to multiple billing systems, or iHIU
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FIRMWARE
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Flamcovent Clean Smart Dirt and Air Separator
Air bubbles and dirt particles are always present in the water of cooling and heating systems. The dirt can accumulate and cause blockages. The use of…
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Flow and return temperatures, and what they can tell us
Flow and return temperatures are not something you want to be watching on a Saturday night says he writing about them on a Sunday night, however this…
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General Plumbing Requirements
All radiators must have TRV's fitted in all rooms except bathrooms and any rooms where a thermostat is located. The exception to this are single storey,…
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Government Policy
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Gravity Networks
This page covers a specific design whereby a building heat network is fed using gravity circulation without the need for
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Grundfos Pump Settings
When you switch on the pump, it runs with the factory pre-setting or the last setting. The display shows the current operation
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Heat Loss Calculations
The following spreadsheet is a simple and standard way to estimate heat losses for a building or
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Heat Meters
Below are links to various heat meter models supplied by Thermal Integration, however other heat meter models maybe
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Heat Network Calculator
An online tool for calculating the efficiency of a heat
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Heat Network Optimisation
Heat network optimisation is the term used for fixing sub-standard communal heating and hot water
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Heat Network Optimisation Whats Included
The following review is a standard procedure aimed to give immediate 3 day insight into current network performance, and an insight into the required…
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Heat Network Protocol
See also https://github.com/heatweb/heat-networkhttps://github.com/heatweb/heat-network for the GitHub project hosting the
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Heat Networks for the 21st Century
What we offer for heat networks is several years ahead of everyone
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Heat Pumps
The following shows peak loads over two days of a 1 in 20 year cold snap. It demonstrates additional electricity load that will be required for such an…
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HIU Comfort and Economy Function
It is common for HIU's to include a thermostatic bypass to maintain heat across the domestic hot water plate heat exchanger at all times, this helps…
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HIU Comparison
This article lists the differences between the Thermal Integration DATA and the Danfoss-SAV Termix Heat Interface
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HIU Differential Pressure Self-Learning Function
The DIGI, DATA and SLIM electronic HIUs, all come as standard with a function to learn the differential pressure of the primary system during operation,…
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HIU in a Wall
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HIU Network Optimisation
Thermal Integration offer comprehensive HIU Network anaylsys and optimisation
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HIU Power Consumption
The following is an indication of the peak electrical power consumption of our
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HIU Riser
The following images show how it is possible to fit our SPLIT HIU's into a riser, in front of the district heating pipework. It is also possible to…
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HIU Test Comparison
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HIU Testing Standards
For too long have we lived with a complete lack of accountability for the use of badly designed or old fashioned HIUs. Until now there has been no…
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HIU Testing Standards v2
The following are a list of amendments we would like to see made in the second version of the HIU testing
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HNTAS
The Heat Network Technical Assurance Scheme is the new quality control scheme for regulating heat networks. If will be enforced by Ofgem, as a legal…
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How does a thermal store work?
Most people think that the modern way to provide mains pressure hot water is using either a combination boiler or an unvented hot water cylinder. This is…
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Integrating Heat Pumps with Thermal Stores
Where a Heat Pump requires connection to a thermal store Heat Bank there are three ways to connect to the
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Is it more efficient to keep heating on 24 hours a day ?
The old fashioned way of controlling central heating, by having it timed to come on when needed and turn off when not, is often described as inefficient…
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ISO14068
ISO 14068 is a 2023 international standard from the ISO 14000 environmental management series that provides a framework for achieving and claiming carbon…
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Ista ultego III
The heat meter generation ultego III with their different series and sizing provides a multitude of combination and application possibilities. In the…
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Kamstrup Multical 403
MULTICAL® 403 is a static heat meter, cooling meter or combined heat/cooling meter based on the ultrasonic principle. The meter is intended for energy…
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Leak Detection and Isolation on Direct District Heating
The DIGI HIU provides direct central heating, with optional leak
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Legionella
HSE guidance states "It is a simple fact that the organism will colonise both large and small systems so both require risks to be managed
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Limescale
The build-up of limescale in domestic hot water supplies and primary systems is a major problem that all heating engineers should be aware of. Problems…
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Limescale: the causes and solutions
The following information on available scale inhibiting devices has been compiled after talking to a number of various manufacturers. The science behind…
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Links for District Heating Designers
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Load Shedding and Shifting on Heat Networks
Relates to: Hot Water Priority, Communal Heating, District Heating, Load Shedding, Load Shifting, Remote
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Local Authorities and Housing Associations
Recent advances in our understanding of how heat networks function has now shed a clear light on the reasons why historically they have performed so
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Logical Heat Network Upgrade Path
This is thinking on the best way to upgrade existing housing stock to zero
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M-Bus
To disable onboard Pi3 Bluetooth and restore UART0/ttyAMA0 over GPIOs 14 & 15
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M-Bus Cabling
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Mains water supplies and how to improve them
Both Thermal Stores including Heat Bank Thermal Stores and Unvented Cylinders are limited in their performance by the mains water supply to a
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Metering and Networking
The following are examples of systems which can be fitted to HIU's to enable metering, billing and networking to be incorporated into the district heating…
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Modbus Registers for HIUs
These are the standard registers used for Modbus connection to
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ModBus RTU Gateway
The ModBus RTU Gateway allows two way communication from the Building Management System BMS to any of our electronic HIU's, using the ModBus Protocol.…
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Monitoring acronym key
If HIU Is a SLIM Extra, with no temperature control of the central heating
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MQTT Topics
With MQTT as the standard means of wiring nodes on a network together, the way signals are routed comes down to the MQTT topic structure. Access to topics…
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Overlapped Diversity
It shows overlapped hot water use for a number of months for a number of systems. The data has yet to be sanitised and totalled, but has been release for…
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PAPER: HIUs
This paper is a study into the known data on the performance of heat networks, with a view to explain the operation and resulting efficiencies through…
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Pipework Calculation Examples
We believe the best way to learn is via examples. It is also one of the key problems with current guidance - they lack any full examples. If they had a…
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Pipework Calculations
This article is aimed at clarifying the design principles that need to be understood in order to achieve both reliable and efficient heat networks i.e.…
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Plate Heat Exchanger versus Coil for DHW
Plate heat exchangers P.H.E’s give a huge performance benefit to the Thermal Integration HEATBANK®. The following graph shows the output of a HEATBANK®…
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Plate Heat Exchangers and Corrosion Resistance
The guide below is an attempt to give a picture of the corrosion resistance of stainless steels and brazing materials in tap water at room temperature. In…
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Plumbing Solutions
This article provides solutions to the kind of problems a typical plumber encounter that we can help out with. If you know of a better solution, please…
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Prefabricated Plantroom
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Problems with BMS and DH
Expensive control systems + value engineering = poor control and
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Radiator Optimisation
Fixed setpoint results in high return temperatures and HIU limiting output on return
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Rationalising KPI‑08 (VWATD) Data Requirements Under HNTAS
The Heat Network Technical Assurance Scheme HNTAS introduces a regulatory framework intended to ensure minimum performance standards across UK heat…
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Remote backup on HIUs
First we offer the old school on site backup if there are any
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Requirements on water quality
Thermal Integration partner with HSF B.V. in the Netherlands who manufacture a full range of HIU's for Thermal Integration but also for the European…
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Return Temperature Performance of Electronic HIUs
Low primary return temperatures are important on district heating systems for three main
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Schematics
See also the Schematic
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Sensor Positioning for Pneumatic System
When installing or replacing the pellet level sensors used on the pneumatic pellet delivery options for MCZ appliances, ensure that the sensor is fitted…
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Sizing Storage
The following example describes the tools we use for sizing hot water or thermal
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Standards and Regulations
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Steps to a Health District Heating System
A communications panel enables wireless communication around a site, as well as remote communication of alarms, reports &
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Substation Documentation
This page is a technical repository relating to our range of substations fitted with Node-RED control
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Substations
A Substation is an essential part of a heat generation, transmission and distribution system, sitting between the heat source and the buildings heating /…
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Suburban Heat Networks
Can I make the maths add up to get my local residents to switch to district heating, in suburban South
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Swimming pools: methods of heating
Heating swimming pools poses additional problems due to the levels of Chlorides and Bromides often added to kill germs & bacteria in the
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Technical Update August 2019
The latest generation of HIU networks instead provide parallel real-time data, where devices are in control of when data is sent, when something…
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The Best DH System we can think of
So, given we have the most enormous range of kit, and there are so many options when it comes to district heating design, it's about time we sat down and…
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The HIU Revolution
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To make District Heating take off
This is a low cost approach to ensuring all heat networks that are installed have access to the most accurate design data, and also comply to performance…
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Types of Hot Water Storage
This article is a summary of all the types of hot water cylinder, including thermal
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Underfloor heating
Underfloor heating has been around for a long time. However, it is only recently that the general public have become aware of the benefits that can be…
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Unvented cylinders explained
What is an unvented cylinder? Unvented hot water cylinders store water supplied directly from the mains water supply, and heat it using either electrical…
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Unvented Hot Water Storage
Unvented hot water cylinders store water supplied directly from the mains water supply, and heat it using either electrical heating elements or with heat…
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Useful data for heating and hot water design
Contents: Properties of Water Graph of pressure losses vs. flow
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Variable Flow Temperatures in District Heating
This article aims to put some figures to the benefits of using variable flow temperatures on a heat
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VART and TART
VART and TART are methods of measuring the average return temperatures in a district heating system based on volume and
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VWART Calculations
The following table shows the VWART figures from the Swedish
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Waste Water Heat Recovery
Information based on Recoup Waste Water Heat Recovery
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Water Quality Monitoring
This article follows our investigation into the use of low cost camera technology to monitor water quality in heating systems by analysing the colour…
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Weather Compensation Control over HIUs
In Denmark is has become a statutory requirement for HIUs to include weather
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Why we like electronic
The following problems all cause considerable problems in the real world for the efficient operation of an HIU and the network it is connected to.…
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Wilo Pump Settings
The heat interface unit is fitted with one of two central heating pumps. The pumps can be adjusted to fit the end users situation. By default, the pumps…
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Wiring: General Wiring Requirements
These instructions apply in the UK and Ireland only and must be followed except for any statutory obligations. Component specific electrical information…
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Zenner C5 Heat Meter
The Zenner Zelsius® C5 ultrasonic heat and refrigeration meter operates with an innovative ultrasonic technology, specially developed for domestic energy…
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Zero Carbon Energy for District Heating
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