Heat Network Optimisation

Heat network optimisation is the trendy term used for fixing sub-standard communal heating and hot water systems.

We have suffered decades of erroneous guidance, a complete lack of regulation, and a systemic refusal to look at operational data until recently.

Heat networks have historically only needed to work. Working efficiently was never on the agenda. As long as occupants had hot water and heating that was job done. And with gas as a standard heat source, there was no need to be careful about temperature drops or commissioning valves to work as they should.

So now we are in an end of the world scenario and just waking up to how poor building services have been in reality. What we do next needs to work, and work well. We can't afford any more theories or excuse our delay on a lack of suitable technology. We have everything we need, technically, to deliver superb value for money low carbon heat networks, but as long as people follow promises rather than data it will be impossible to effect real change.

The past five years has seen a huge focus on HIUs. It was obvious that HIUs were one of the root causes of inefficiencies, with a wide variety of designs and levels of quality, and a strong tendency for the industry to value engineer out anything related to efficiency. Establishing standards was a very important first step, and the BESA independent testing gave us that. We were lucky enough to be in the first set of tests, and have been heavily involved since. Our hydraulics and controls expertise delivered us the best test results by far, with return temperatures not far off theoretical perfection, and have never been matched in the years since. This is not said as a boast, but rather as a testament to the use of data to develop products that actually work. Without a proper feedback loop, it is impossible to improve technology, just as it would be to improve a recipe you never taste.

Heat networks as a whole are no different. To the untrained eye energy centres generally look like impossibly complex. Looking at schematic drawings on the walls they appear to be highly engineered machines. But once you get to know them, its quite a different story. Generally a glance at return temperature gauges gives it away, with a one or two degree temperature drop. But that's down to the network, the HIUs, so as long as the practices are in place to correct that side it should all, theoretically, work.

Again, experience shows otherwise. The layouts of most energy centres often makes it impossible to run a an efficient system, even once the network itself is delivering decent return temperatures. The use of headers and bypasses has historically been prolific, and the standard forms of boiler sequencing simply do not work well with a heat network that likes a steady flow temperature. Buffer stores are rarely used, and where they are used are never installed correctly. Pumps and boilers are commonly so oversized as to make it impossible to match low load conditions without rapid cycling.

One of the best examples of how reality differs from practice is radiator balancing. A critical factor in achieving low return temperatures, yet in practice they rarely work. Only those network operators that have invested the time in monitoring know the truth of how difficult it is to achieve a 30C drop specified. In practice, anything more than 20C is doing very well in the UK. Yet there are simple well tested solutions used in other countries and on very rare occasion in the UK.

And then we come to the biggest hurdle of all, the controls. As manufacturers of HIUs and substations we often have a need to integrate with building energy management systems, however we have found this to be almost impossible due to a lack of centralised technical support to discuss modern protocols like MQTT. Almost all BMS systems are designed to lock one into contracts and licences rather than do the job at hand. Many BMS controllers are deliberately throttled down to enable them to charge for decent processor power (that you have already paid for). Every control point carries a licence, as does every modbus interface. You are then locked into a centralised network where problems like an IP clash can take down numerous sites at once. In short, it is simply impossible for anyone other than the employed BMS installer to write, check, debug, and improve controls logic. Its no wonder very few control panels have ever even been connected for remote monitoring, either because of the costs involved or for reasons of plausible deniability. Without any remote data, and nobody ever having the desire to even look, is it any wonder the things never worked?

So, now we are aware of the scale of the problem, who do you approach to fix these monstrosities?

At Heatweb we have been working for roughly ten years on the development of open-source monitoring as an in-house tool for product development. We are unique in the heating industry as pioneers of pre-fabricated thermal storage and plate heat exchange systems with many thousands of installed up and done the UK. Not just any standard system, but custom made, complex multi-fuel domestic heat networks of various sizes, all working perfectly. It is this experience that enabled us to achieve the unmatched HIU performances we have, and this experience comes from designing, building, deploying, and monitoring products in the field in order to improve them. We have been integrating heat pumps with boilers, biomass and solar thermal for decades, and nothing is guesswork or theoretical.

In our recent endeavours assisting local authorities with optimisation, we have learned that only open-source monitoring allows you to achieve success. It is the only way to beak the link between cost and efficiency - as long as it costs more money to add data points and functionality there is a point where commercially driven installers will stop. And where they stop is where you stay. As soon as data points and functionality becomes open-source and there is no additional cost to deploying an upgrade, then systems start to evolve. The ability to connect remotely into an energy centre and tweak the logic is not just a luxury - it is quite simply the only way the system can ever improve.

This is why nearly all optimisation contracts start with the installation (temporary or permanent) of a Heatweb control panel. Our panels are factory assembled and tested with the controls and communications we need to see what's going on, and then if needed take control of things. Components include a GSM modem, a touchscreen, power supplies, industrial I/O modules, an M-Bus master, Ethernet switch, and most importantly a set of controllers running open-source controls software provided by IBM. The software loaded into controllers evolves over time, and it is simple to copy and paste between systems. So added functionality, such as Modbus control of equipment, can be pulled in without any licences.

Such panels are very low cost, take a few hours to install, and provide a contract-free platform to access real-time data from the energy centre, starting with simple temperature and differential pressure data. This is in effect the same as when a Doctor initially may take ones temperature, blood pressure and heart beat when starting an examination. To do a proper examination you must be able to check the vitals. And check them properly - not every 15 minutes, but every second, continuously, day and night so we can see every little detail.

Once you start getting data, you start making informed decisions. Couple that data to a proper hydraulics expert and you get working solutions without any guesswork involved.

The greatest benefit of all with open technology is its easy to prove it works. There is a lot of data coming out of heat networks that have been successfully optimised to prove it beyond any doubt, including both HIU networks and those with centralised DHW storage.

Heatweb are asking local authorities to join in the open-source mission to improve heat networks. To stop taking risks and listening to opinions, and instead follow the data. To collaborate and evolve the technology to what we all want it to be.