IHIU Control Systems

From Heatweb Wiki
Jump to: navigation, search

IHIU Control Systems

The software that runs all Thermal Integrations electronics is subject to copyright law, and must not be copied without written permission from Thermal Integration Limited. Any code provided either through any of the Thermal Integration websites (heatweb.com, systemdesigner.co.uk) or on equipment, is covered by copyright, and is provided in order to assist customisation or development of the software. Software provided on equipment may be backed up or altered, but must not be distributed, replicated, or used for commercial purposes.

A number of patents, both granted and pending, apply to the software and equipment manufactured by Thermal Integration Limited that may be detailed in these pages. Operational details on any patented designs, provided either through any of the Thermal Integration websites (heatweb.com, systemdesigner.co.uk) is provided for both design servicing purposes, and is protected by UK and international law.


IHIU Controller, v2.1
Browser based front end

The IHIU controller represents the height of modern Linux control systems, providing a very powerful open-source software environment capable of connecting to virtually any device, while at the same time costing a fraction of the cost of traditional proprietary electronic controller.

The miniature computer has built in Ethernet and WiFi, and runs the same software that runs on most internet routers, making it a powerful hub for secure communications to almost any network connected device or server.

Although the controller does have numerous inputs and outputs, its USB port, expandable by the use of a USB hub, allows one to also connect almost any peripheral designed for computers, from USB storage devices, through to GSM dongles, RS485 devices, or even cameras, making it more than just a controller for hot water systems. The IHIU has ModBus Master functionality, allowing it to connect to ModBus devices, read and write registers, and act as a bridge to other networked systems. You can also connect wireless mesh networking dongles to establish site wide self healing networks with secure communication from any controller on the network through to any other controller, including ones connected to the internet and acting as bridges.

It runs at 5v as standard, making power supply straightforward, and allowing the use of backup powerbanks, or super capacitors, and making it easier to power from lower voltage sources such as PV cells. A PoE (Power over Ethernet) option is available.

And as for software, the Linux system runs a number of software languages (including Python) and can host powerful PHP driven web sites, as impressive as almost any seen on the internet. The user-interface is indeed a PHP driven website running JQuery - the system that powers responsive websites that change their format depending on the device upon which they are viewed. Its power can be extended by the use of online APIs, allowing the system to interact with Dropbox, Twitter and Amazon, or send emails and text messages. Furthermore, one can edit software using the built in editing packages, and even use the built in graphics editor to design a system dashboard, that will run in any web browser.

We have loaded all the various software functions into packages that can be downloaded from our web site directly to any controller, enabling it to switch roles in an instant, and should the software running on the controller need to be customised in some way, it can then be uploaded to the web site for download to other devices.

The Internet of Things has arrived.

Hardware Features

Patented Heat Exchange Process
  • 12 Analogue Inputs for Temp/Flow/Pressure sensors. Connector blocks to match Grundfos Direct Sensors.
  • 8 Digital Input/Outputs or PWM control for connecting switches, relays, and pumps.
  • One-Wire temperature sensor connections with one on-board sensor
  • Pump speed control
  • Twin processor motherboard 7 x 5.5cm
  • WiFi connectivity
  • Serial connection
  • USB socket for peripherals such as a z-wave radio dongle or camera
  • SD Card for storing software, documentation, and configuration files

The picture opposite is an example implementation of the circuit, used to control a heat exchange process. The process in this case is a patented heat exchange process using pump speed modulation to respond rapidly to changes in hot water flow to taps. The circuit uses solid state relays to drive mains components, with a PWM output controlling pump speed. Grundfos 5v temperature, pressure and flow sensors are used to provide the circuit with a complete picture of whats going on.

Software Features

  • Easy installation of IHIU Software Packages and IHIU Software Extensions
  • Linux operating system
  • PHP5 server
  • Main control software written in PHP and Python
  • ModBus RTU Master functionality
  • Context sensitive software editor
  • Html editor
  • SVG dashboard system
  • SVG graphics editor for designing dashboards
  • File manager
  • Editable menu system
  • Remote software updating
  • Uploading of software snapshots with version tracking
  • QR code integration - if logged onto iHIU on a phone, you can photo QR codes to run programs
  • Timeclock control of parameters by time, day, or date
  • Learn feature for parameters
  • Data logging with historical data saved both locally and online
  • Powerful graphing features
  • Integration with Yahoo weather for external temperature data (current and forecast)
  • Integration with Google Translate providing multilingual capabilities
  • Emailed alerts
  • Access log

The system is based around two processors, one connects to input and output pins (for connecting sensors, relays, pumps etc), while the second, more powerful processor, acts as a web server and performs calculations. The first processor sends its readings to a specific web page on the iHIU server (operation.php), and receives instructions by reply.

The on-board WiFi connects the iHIU server to the Internet and allowing to periodically log data to the internet and check for instructions, or if there is no WiFi the device acts as a WiFi end-point, generating its own WiFi zone you can log on to.

The user can connect to the web site hosted on the iHIU server, using any computer, tablet, or smartphone on the same network, and if the wireless router is set up to redirect http requests to the iHIU one can view over the Internet (as you currently are). This web site allows one to alter control parameters, as well as edit the software that runs the system. The software is written in a language called PHP and is very powerful, allowing one to write very complex logic, as well as retrieve the contents of any web page or file (local or over the internet).

The ability to edit the software in-situ, and even remotely, allows the system to be deployed with the most basic working program in place, and then following a period of monitoring, the program can be improved as seen fit. Once the program works perfectly, it can be uploaded to the internet for deployment to any other devices acting in a similar role. The software is edited in place using a text-sensitive code editor that colours text according to its meaning, and highlights certain errors.

With the entire system built around a PHP web server, it has been possible to rapidly re-deploy many of the functions already used within our web sites (also PHP web servers) over to the iHIU.

As an example of the potential, consider a hot water system that purchases its own fuel online at the best market rates, and while its at it trades in the fuel commodities markets to make you money to pay for your deliveries.

Cross Platform Interface

User and engineer interface to the IHIU is provided through a browser on a device on the same network as the IHIU. The IHIU serves an interactive website, that provides access to all the system features, while adapting for the screen size of the viewing device. The system is equally manageable on a mobile phone as from a PC or a tablet.

Welcome screenDashboard of storage controllerSVG Dashboard EditorOnline graphingSystem settingsRemote software updateDashboardMobile phone menu systemLive graph at 5 second resolutionSystem settingsNetwork scanningSoftware editorProgrammer


To view the operation of your system, and make sense of data, a graphical dashboard can't be beaten. Elements in a dashboard can be set to auto-update creating a live display of whats going on, and this can include the colouring of pipes and vessels to represent their temperature making it far easier to gauge the entire system at a glance. Elements can also be interactive, displaying further information when hovered over, or linking to other pages or pop-up screens when clicked on.



Being able to examine how sensor data varies with time is a cornerstone of fault finding and development, as it allows one to spot events and determine causes without having been there first hand to witness events.

The IHIU control systems uses powerful graphing software to generate attractive and interactive graphs of all data. Readings can be displayed side by side, and the axis automatically scale to suit values, and it is possible to page back to any days graphs historically. The level of detail is only limited by the settings, and it is quite common during detailed analysis of systems to record over twenty readings every ten seconds for months on end, providing vast amounts of data that can be graphed and zoomed in on to properly analyse system performance at any required resolution.

Online Service Portals

To increase the power of the system, you can make use of applications hosted online. These applications can be obtained in much the same way as apps for a phone, through our online store, with some for free and some costing either a fixed sum, or charges for ongoing services, and some will even be downloadable to the iHIU to tun locally without needing to connect to the internet one installed.

Applications will typically appear as a item in the menu system, providing their own web interface, and based around PHP driven software. When you install an app you a effectively bolting on new web pages, running on your iHIU, that can also act as a gateway to pages hosted on the the internet. These pages can be used to either provide a user display, or to add software functions that can be made use of within iHIU code.

The iHIU online functionality in development includes:

  • Sending data to the Energy Saving Trust's Embed Database to provide free, scaleable, secure data storage that can be used anonymously to further public understanding of system efficiencies
  • Heat Network Management
  • Locating and providing information of local registered heating engineers
  • Heating engineer calculator suite
  • SMS Services
  • Email Services
  • Data Logging and Graphical Analysis
  • Weather data and forecasting
  • Maintenance management system, allows you to set up group of approved service engineers and administrators, manages communication of alarms and updates, and establishes and organises routine maintenance and reporting
  • Access to engineer database, allows a maintenance management system to make use of our extensive database of approved engineers, in numerous disciplines, and backed up by the one of the largest renewables and biomass training centres in the UK. Engineers are rated through the system.
  • Spares parts provision, links maintenance management to automated online purchasing of required spares, with delivery of parts either to engineer or site
  • Twitter and Facebook interface for sending commands and viewing alarms (Free)

Thermal Integration have in-house software engineers adding continuously to the list, however it is also possible to write your own apps in PHP and if approved, place them in the iHIU online store for others to download either for free, or otherwise. We try not to charge for applications that are already available in a form freely somewhere on the internet, and where applications are charged for it is a reflection of the cost of providing value added services.

For an example of a full product feature set, see IHIU Sequel Functionality.

One of the most attractive features of having multiple HIUs logging data to a central server is the ability to view the entire network in a dashboard. Information logged from each iHIU in a group, can be tabulated alongside other calculations, and warnings.

Graphical dashboards are also possible based on SVG graphics format.

Along with the facility to graph live and historical data.


Tweeting is a very useful method of posting messages, and the iHIU as standard has the ability to Tweet. It also has the ability to read Tweets, making it a viable means of sending commands to a system. The advantages of using Twitter are its familiarity to users, as well as its availbility on any platform.

Tweets can be embedded into web pages on the iHIU or online, thereby allowing them to be used in dashboards and management screens. You can follow systems, re-tweet, and make use of all the other functions that Twitter has to offer. Bearing in mind that the iHIU can tweet to either people, or other iHIUs, and can also respond to tweets fom people or iHIUs they are 'following', the possibilities for networking systems and setting up levels of alarm reponse are very interesting.

To improve the intelligence of the Twitter system, we have implemented a means to teach the iHIU how to respond to tweets. By sending the following two tweets to an iHIU (Twitter name iHIU) the system will learn how to respond the next time it sees a similar question:

@iHIU Q: What is your favorite colour ? @iHIU A: Blue.

The system should respond "Thankyou. Blue." This is a fairly simple example, and it is also possible to teach the system more complicated responses making use of sensor values. In the following example, tCHf and tCHr are the standard iHIU codes for central heating flow and return.

@iHIU Q: What is the central heating temperature ? @iHIU A: The central heating flow is at #tCHf, and the return is at #tCHr.

As an option we can set other iHIUs to update their learned responses accordingly. The theory is that with time, systems should evolve to the point where they can answer most of the questions users may ask the system, without the need to ask a human. If further assistance is needed (the iHIU doesn't understand the question) then web links or contact details can be provided.

Background to the iHIU Controller

Low cost (yet very powerful) embedded networked computing is now a reality. Who would have thought a few years ago that one could buy a full blown computer for under £30, and run it with freely available software. Furthermore the hardware designs are open to everyone.

Expensive BMS systems can be replaced by low cost and more flexible alternatives. One of the most widely known system of recent is the Raspberry Pi, or the numerous flavours of Arduino circuit boards. Arduino circuits have the ability to plug in expansion cards, and at the moment there are well over 300 such cards extending functionality to cover anything from stepper motor control, to touch screen displays, and if you want to make a new type of expansion card, you can design it using freely available circuit design software and have it manufactured and in hand within two weeks for under £20.

Open Source hardware and software

This allows 'the whole world' to take part in improving and evolving systems, accelerating the rate of product development. It allows individuals to experiment with new ideas and if successful these can then be pulled into standard software distributions used by everyone. The end software product, is free to use, and maintained by users.

There exists a huge network of the worldwide developers, linked through shared development web sites, who are busy evolving the design of communal software in all fields, at no cost. As examples, one should look at freely available program's such as OpenOffice or Inkscape, each as good as their rather expensive commercial counterparts, and evolving rapidly. Online software (APIs) still allow commercially valuable software to be protected, however one can be assured that almost any system that charges for its services will eventually be circumvented by a freely available open source counterpart.

At Thermal Integration we have embraced this new world, both building open source software into our technologies, as well as providing a powerful suite of editable software within our control systems. It is our view that to provide a properly networked building services infrastructure, a number of different systems are going to need to communicate. The use of common wide area network technology, web protocols and security, enables almost any web connected device to participate. The IHIU control system provides an onboard software editor, allowing rapid development of new code. We have built in a package manager to allow the upload of software to a server, where it can be downloaded to other devices. As all this is driven through a web interface, there is no requirement to install development software; just a web browser and a working knowledge of PHP language (the most widely used, supported, and documented web software there is).

Online APIs

Application Program Interfaces are simply online web pages that provide data to a program or browser, thereby increase functionality, such as the use of google graphs, google translate (so implementing multiple languages is straightforward), or Yahoo weather. Any web site can act as a means of providing operational data or instructions.

As a simple example, having access to the best online weather forecast data can help improve heating efficiency. As an example, where the next day is forecast to be bright and sunny in the morning, stored heat can be used up the night before, ready for solar thermal input. If the weather is forecast to be overcast, then the systems can make use of cheaper overnight electricity.

APIs may include:

  • SMS messaging
  • data storage
  • payment gateways
  • the use of valuable data such as up-to-date post code information
  • automatically ordering spare parts
  • linking devices to local engineers
  • managing fuel purchasing and delivery
  • RHI meter read updates

Servers, Browsers, Smartphone and Tablets

Modern WiFi devices such as tablets provide powerful user interfaces and remove the need to implement on-board touch screens, buttons and displays in equipment. Control systems can act as web servers, making use of the browser functionality built into users preferred interface.

Almost everyone is familiar with accessing a web page, and accessing the iHIU control system is no different, except the web page is hosted locally.

  • The server (equipment or product) can make use of powerful server-side programming languages such as PHP
  • Browsers provide many form input features aimed at simplifying user input
  • Multiple user interfaces customised to suit the user
  • Graphical dashboards
  • Large font sizes and audio for the visually impaired
  • The seam between access to pages hosted on a device and pages on the web is invisible

Constant Monitoring and Improvement

Routinely monitoring systems (with permission) and storing data on the web, can provide very valuable tools for analysing, and hence improving, system operation. Every system out there becomes a valuable source of analytical data, without the need to setup expensive test beds and monitored sites.

Unanticipated installation variances that effect system efficiencies will no longer go unnoticed for long periods, but instead can be seen as they occur. Remedial action can be applied (remotely in some circumstances) and monitored for effectiveness.

System efficiencies can be monitored and those that show the greatest efficiencies can be analysed and any user behavior or installation parameters that stand out as resulting in the best efficiencies can be determined and applied to other systems. This is especially useful in systems that learn, such as when occupancy sensors are linked to central heating zones. Systems will be able to learn the typical patterns of use, and adjust on/off times and temperatures to meet demand. These learned patterns can then be applied to similar installations from day one.

Of particular relevance at the moment is the need to learn the best way to manage biomass boilers and thermal storage. Efficiencies are particularly affected by how often a boiler goes into full shut down and startup. The way boilers are currently managed is to significantly oversize storage (25 litres/kw) in a blunt attempt to reduce this cycling, however this has the result that stores are simply too big for many installations. A better approach is to learn how to manage the size of a thermal store buffer and how often to call for heat in order to minimise cycling. The data gained from managed installations over the coming months will provide a means to calculate and demonstrate the best approach, which in turn will become standard practice.

Networked Heating

Moving on from the systems intelligence itself, the future for heating systems is heading in a direction of district heating. Networked supply of heat offers considerable advantages as already seen throughout the world. Managing such systems using networked intelligence is an obvious progression, with efficiencies gained by having individual household systems communicating their predicted demand patterns to boiler plants, and even electric suppliers. The National Grid is already networked to many commercial buildings heating and air conditioning systems to automatically shut off or reduce electrical load at times of peak electricity demand. Heat supplied through district heating networks can be similarly managed, and it is here that the greatest benefits from networked systems can be seen.

Billing Systems

One of the currently networked systems typically installed in properties on district heating is a metering and billing system. This collects data from a heat meter and sends this to a central server somewhere to allow managing agents to charge householders for the energy they use. Up to now the systems have been fairly dum, simply acting as data collectors, with the more advanced also allowing a security valve to be implemented to turn off the heat source when finances run out.

The next generation of billing systems will radically increase the functionality that can be provided through systems, and allow them to fulfill many of the roles and functions described so far. As billing systems already connect to hot water and heating equipment, the added advantage of having financial services already linked to the device makes them the obvious choice for acting as a the main networked controller for the entire system.