Data Monitor v1

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Finalist in 2016 Combating Legionella Awards
Can be used to manage HIUs in sets

The DATA Monitor system is a Linux based controller that bridges between HIUs and Ethernet or Wifi.


The purpose of installing a Monitor alongside HIUs is to:

  1. ensure efficient operation of both HIUs and a heat network
  2. minimise problems by identifying and alarming issues before they become critical
  3. eliminate unnecessary service call-outs
  4. eliminate guesswork when changing components
  5. provide data that can be useful to future designers


The Data Monitor v1 is compatible with our range of electronic HIUs:

The DATA HIU has achieved the highest efficiency figures of any HIU on the market, as officially proven during independent testing carried out SP Technical Institute of Sweden and funded by DECC.

The functionality in the Monitor extends the functionality of the DATA to realise its full potential, taking full advantage of the benefits of intelligent control and networked communications.


We aim to make HIUs compatible with 3rd party systems, to enable all the services on a site to be managed through a common infrastructure, including the use of home displays and plantroom control. To this end the Monitor can act as a bridge, connecting the HIU functionality to other systems through:

  • Serial RS485/232
  • WiFi
  • Ethernet
  • Bluetooth


The system performs the following functions:

  • Connects to four HIUs directly, with ability to expand.
  • Ethernet and WiFi connectivity.
  • Provides a web browser interface for managing system.
  • Encrypted communications.
  • Reads all sensor and operation data from HIU every second.
  • Detects changes in HIU data and logs to local storage.
  • Periodically logs to remote storage.
  • Detects errors through both error codes from HIU and further diagnostics.
  • Email alerts.
  • Automatically sets up new HIUs to required settings.
  • Provides secure engineer/concierge dashboards for managing HIUs connected locally, as well as elsewhere on network.
  • Historical graphing of sensor values.
  • Five second logging for one minute following change of state (for confirmation of DHW response).
  • Provides facility to remotely effect heating loads across all HIUs (in response to plantroom requirement for less load) - patent pending.
  • Proves facility to weather compensate return temperatures across all HIUs.
  • Can be customised to suit.
  • Back-end software functions available to integrate into 3rd party platforms.
  • Option to provide M-Bus Master functionality.

Reduced Workload and Less Time on Site

We aim for our systems to be as close to fit and forget as possible. For example, we have some 4,000 Heat BankTM mains pressure maintenance free thermal storage systems across London, spanning 20 years and numerous local authorities and house builders, that still work as intended - only needing a call on the rare occasion something needs attention.

It is however a general requirement to check up on HIUs every two years to check they are not damaged. Such a regular check would also normally require testing the system and checking operation of components to ensure efficient operation. Such a service call can take up to an hour, and requires breaking security seals on an HIU - its rare in fact to see seals in place on HIUs simply because of the number of times casings are removed for one reason or another.

With HIUs connected to a Monitor, they are been constantly diagnosed for any potential problems. This is done locally with no need to store long term data, locked away in a cupboard, and very nearly completely removes the need to remove the HIU casing and break the seals unless something needs replacing.

Even without any form of network connection, a Monitor in a riser will give a service engineer access to error logs and enable settings to be altered, but this still needs an engineer on site. Once the Monitor is on a network and can send alarms, we have a situation where the person in a call centre taking a call from an occupant can learn more in 30 seconds than the best service engineer kitted out with temperatures and pressure sensors can hope to achieve.

Therefore... a two-yearly service call can become nothing more than a few minutes visually checking the HIU and heat meter for damage, as one knows before even walking in that the unit has been operating perfectly to date. Most importantly the security seals are not broken, and we may suggest the fitting of an external strainer to let this be checked as part of the 'in and out' procedure. Obtaining access for brief visits is far easier than hour long procedures.

Where an HIU sends out an alarm that a component is wearing out, replacement can be booked in when an engineer is in the area doing visual checks. An automated email or SMS to the occupant to ask them to confirm best time from any options would go a way to reducing involvement. The service engineer can then be informed of the booking, and provided with a schedule of works and a parts list.

With the reliability of our components and HIUs already proven over many years and thousands of systems, we are confident the prospect of saving a decade of pre-emptive service calls, by trained engineers with tools and spare parts, will be very attractive to clients who have to live with systems long term.

And it will evolve, to make life easier. Problems that go uncaught can be investigated, comparing data before the failure to data following component replacement, providing the clues to write functions to trap it next time and alarm in advance of failure.

Open Technology

We are a manufacturer, and stick to what we are good at, so when it comes to the question of open systems versus closed ones we prefer an approach that allows us to co-operate with other service providers.

At the core of the Data Monitor are the Python software functions to connect to our HIUs, logging data and sending commands, and it is the sign off on these that the launch of the monitor represents. These functions are portable to most systems, and on many should run as is. On top of this are PHP web pages that provide the front end management screens, dashboards, and window dressing, as well as handling encryption and remote logging.

The hardware itself - the circuit board that runs the code and plugs into the HIU via a USB port, is almost inconsequential, with a large choice of compatible low cost systems out there.

As an example of how we have connected to other systems, the Energy Saving Trust worked with us to write Python code to enable monitoring platforms to log data to their EMBED database. This was itself as part of a desire to deliver the first open-source platform for remote monitoring to the requirements of DECC's Monitoring and Metering Service Package.

History behind the Technology

As a manufacturer of custom hot water systems, including some of the most complex renewable combinations ever attempted, we have always indemnified our designs. All fine and dandy when you know what you are doing, but sometimes customers ask you to push the boundaries, and on occasion the interplay of system has unanticipated effects. Remote monitoring first moved from the shed to site when combining a wood burner, heat pump, electric cheap rate elements, mains pressure hot water, underfloor heating and radiators. Normally a walk in the park for us, but it was found after hand-over that the high-grade heat from the overnight electric storage was been stolen by the underfloor heating, so hot water availability ran sort in the mornings. Only by applying a lot of temperature sensors feeding back data to us every minute were we able to see exactly what was going on. It allowed us to engineer a fairly simple diffuser tube to redirect currents within the store that was retro-fitted and problem solved.

More recently, our group partners, Specflue, have been at at the forefront of trying to educate the biomass industry. We have the UKs first and largest biomass training centre and last year supplied more biomass boilers in the UK than anybody, however skills on site are not always what you hope for. In biomass its all about training, because its so dangerous and hence the training centres, but with RHI ramping up activity and creating incentives to deliver inefficient systems, remote monitoring is sometimes the only way to 'see' a problem. The Monitoring an Metering Service package from DECC was introduced to drive the use of remote monitoring, but nobody signed up due to the cost and complexity of remote monitoring, so we felt it would be good for the industry if there was a low cost open-source platform to deliver the service, making use of the EST's EMBED database as a contract-free mechanism to log the data.

District heating network are much like biomass systems - a growth industry where anticipated efficiencies are not been met in general. The remote monitoring of networks and HIUs is a simple way to ensure a healthy network. The same system also allows us to realise the full potential of our HIUs.

Demo Engineer Dashboard

The following demo is from a Monitor connected to an HIU in the factory. The HIU is not connected so temperatures are approximately room temperature, and pressures are zero. A few errors have been simulated by unplugging sensors. We will soon be adding more data sets into the demo to simulate real life conditions.

Where more than one HIU is connected, there will be a different column for each HIU, enabling the entire site to be accessed from a single screen. This dashboard is currently only made available on the local network, and not off-site, although individual HIUs can be remotely commissioned if permissions are given and data stored remotely.


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Control Panel

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Performance Guarantees

Eliminating human error and time limitations from commissioning HIUs, checking performance, and diagnosing problems changes a lot.

It is straightforward using a monitor to confirm that every HIU on a network is 100% perfect, not one setting a degree out, no bypasses open anywhere, no blockages in pipework, and all consumer demand met within requirements, without even thinking about it. Anything requiring human intervention is flagged.

What would until now require a full maintenance program, advanced letter warnings, phone calls to confirm, and numerous days on site, can now be achieved in the blink of an eye, reliably, and automatically every second of every day.

It may also be worth a mention that been able to guarantee performance also covers been able to guarantee Legionella requirements are been met, everywhere.

For performance to be properly guaranteed however requires more. Monitoring a system is no help if the equipment you are monitoring cannot achieve the loads or performance you require, or suffers from design flaws, and this is where we offer the best guarantee there is - independent performance testing under a standardised UK test regime for HIUs that proves the DATA HIU to be industry leader by a country mile.

With the Monitor we aim to revolutionise the way networks are maintained, much in the same way we have advanced HIU technology itself.


The software is Python and PHP based, built on standard forms of communication an security, and should run on all Linux systems, as well as some other platforms. It is not tied to one specific type of electronic circuit, other than the requirement to run the software and have a USB serial port. This provides the customer with the certainty that the hardware, rather than been bespoke, is mass produced and used in the millions worldwide. Spare parts will always be readily available.

The current version runs on a Raspberry Pi 3, using a large SD card as well as precautions to ensure files are not re-written to extensively in order to help ensure a long SD card life.

We have gone via the Raspberry Pi route, rather than our own bespoke solution, is for the following reasons:

  • A reliable and fully CE approved circuit board tested on millions of customers
  • Option for CE marked industrial touch screen display or HDMI screen
  • Powerful processor with all peripherals for connection included
  • Well developed stable open-source operating system that implements all the standard internet security protocols and can act as a web server
  • Very low replacement cost
  • Used in very high volumes with regular operating system updates
  • Hardware developers can take software implemented on a Pi and implement it into their own systems

SD Cards and Storage

Despite the fact we haven't yet experience an SD card failure, it is a possibility, or one could say a certainty at some point if not swapped out during planned maintenance, and although the Monitor is not service critical, and SD cards are very cheap to replace, the call-out charges for replacement may not be.

SD cards also introduce a security risk, been removable and replaceable if access to the Monitor can be made by the public.

We will soon be offering the Raspberry Pi Compute, which used 4BG of flash memory storage instead of an SD card, with USB storage used for logging encrypted data for long term storage for decades of data. We also have the system running on other common Linux micro-controllers that run from flash memory but have optional an SD card, where the more advanced desktop features of a Raspberry Pi are not required.


To log into the Monitor, one needs to have registered on to obtain a unique username, and the username must be granted permissions on the Monitor.

Differing levels of permissions provide access to differing levels of functionality.

Direct access to Monitors remotely would typically be achieved by the use of a secure VPN.

It is however normal that the network is not accessible from the outside world. Monitors send out data when they decide to and can pickup mail from a remote server in the process, so there is no need to open the system to the outside world.

Data Protection

The information provided by our HIUs is exceptionally detailed, and updated every second, so it is quite important - in fact a legal requirement - to ensure data privacy is protected.

One has to ask, who would I like to have access to detailed records on my personal washing habits, and who do I trust with the knowledge of when I'm in or out, and when I go on holiday? - as this is the type of information that can be guessed at from HIU data. And even if you trust someone, do you trust them to safely protect your data, say from unscrupulous employees?

The whole point of such data is to identify potential problems, so that incorrect settings can be corrected for optimum efficiency (i.e. lower running costs), or failing components can be spotted and an engineer visit scheduled, so it is in the users interests for historic data to be stored - provided their data is safe.

Out of the box, the Monitor will send all data to our servers. This is to assist in the commissioning and hand-over stages. Following this, rather than send all the data to a web server for analysis, the Monitor can use the built in monitoring functions to identify potential problems and raise an alarm, only posting out data that is relevant to the issue in hand, while not giving away historical usage patterns.

The Monitor uses 2048 bit Open-SSL encryption in communications and optionally in local data storage..

There is a desire to use data from systems to advance knowledge, such as to improve an understanding of diversity on a heat network. This type of information does not need to be identified against a particular property, so it is an optional function for daily readings to be anonymously (random flat number) posted to a remote server, such as the Energy Saving Trusts EMBED database, only identifiable by site.

No Personal Data

We do not believe any of the functions of the HIU need to be tied to an individual, just in the same way that your gas boiler controls are not password protected.

As it stands the system requires no personal data, or even passwords to function.

Access to the settings is provided by a unique web address, obtained by scanning the QR code on the HIU. To gain access however requires one to be in the property, and this can be proven by requesting the user to run a hot tap for 5 seconds. This allows anyone taking residence to have immediate and secure access to their system settings.

Without a need for user names and passwords, as well as no need to store phone numbers or address details (the address is fixed), data protection is about as well protected as it can be.

User Management

Scan this on your phone to view demo user interface

How permissions are given can vary, with one option been the use of a QR code on the HIU itself that takes occupants to a management screen for their system using a mobile phone or tablet. This can provide (although still in development):

  • Easy, password free access using unique QR code
  • ID can be confirmed by the system asking the user to 'run a tap' or 'turn off heating'
  • Request for new QR Sticker by post - for new tenants
  • Instructions
  • User Settings
  • Service history
  • Report issue
  • In any language
  • A list of access requests, based on email address, to be ticked - examples:
    • All data to manufacturer - can be turned off following hand-over
    • All data and settings to Call Centre, Manufacturer, Maintenance Company for next 48 hours - e.g. to monitor reported issue
    • Hourly data on heat network performance (not use related) to Estate Manager (
    • Alarms to Maintenance Company, Estate Manager
    • Alarms and related operational data to Manufacturer
    • Ability to change user settings to Concierge
    • Ability to change operational settings to Estate Manager
    • Monthly randomised data to Manufacturer, PUBLIC - cant be identified to any particular address so safe for public release for the greater good. Location accurate to first half of post code.
    • Confirmation of all access and changes in settings to occupant by email/SMS.

With such a system, there is little need for data to be stored locally longer than one month. Nobody receives copies of historic data that can be identified to a specific address. The only property specific user related data sent would involve a system alarm, and therefore quite rare.

Once a user has scanned the QR code they can save a link on their device home-screen and have remote control over their hot water and heating when home or away (if password protection is turned on).

Heat Network Calculator

To enable rapid online modelling of a heat network we have developed the Heat Network Calculator. It is a free to use no registration tool built to work through a large number of system variables to estimate seasonal efficiency, pipe sizes, as well as boiler and buffer store sizes.

It is our aim to connect anonymous data from HIU to the calculator so that a growing real life data set can be used for calculations. This will help confirm assumptions and improve the accuracy of the calculator.

We also intend for the Calculator to act as a tool for generating dashboards that can work with the Monitor to create a full colour coded representation of the entire heat network, mapping temperatures and pressures. The Calculator can accept individual values for flow into each property and use these to generate a full colour coded, to scale, map of the network. As a result, flow rates through every piece of pipe are known, along with calculated pressure drops, so deviations in HIU readings from predicted values will help highlight blockages and open bypasses.

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