Lighting, heating, irrigation – timers are an essential part of intelligent automation.
By Simon Buddle
Summertime and a time to relax a little, and to do some of those chores we never get round to. Time to throw out those old actuators that have been building up in the corner of the workshop – you know, the ones you had said you will try and fix, but never found the time. Time to check stock levels, and even do a stock take. It’s astonishing how much stuff we accumulate and the value of it. But in the main, it is a quieter time of year.
There are those who love their gardens, spending hours with their hands in the soil, pulling weeds, potting on (a phrase I learnt from TV gardening presenter Monty Don) and making a wonderfully tranquil space for themselves and the natural world. For me, I lose interest if the tools required don’t have a large pull cord and make a noise like a small motorbike. I will do the lawn, power assisted of course, and I am happy with a hedge strimmer. Anything more delicate than that and I will need a lot of watching over to be sure I am not dead-heading the wrong plant.
Summers feel like they are getting longer and drier. Water remains a persistent concern here in Europe, and across the wider world. We have either way too much in a truly short space of time leading to dreadful floods, or we are kicking around in a dust bowl for weeks on end.
For those who love their gardens, neither of these are good, but the worst is the ongoing dry conditions over the summer. Months of planting, weeding, cutting, and shaping can be ruined without water in the harshest moments.
Timers
Within the KNX environment, we can add timers to any control output that we have installed. For example, we can add a simple On/Off for a towel rail where we know the family uses the bathroom from 06:00 – 09:00 and 19:00 – 23:00. We could automate the On/Off using a timer on the user interface. This timer should be visible to the homeowner so they can override or edit as needed. This simple principle holds true for so many KNX-connected elements.
The timers we have available today adjust for daylight saving, such as British Summer Time (BST), and they can be set as astronomical clocks, i.e. they adjust the time when a function happens, based on the sunrise and sunset times as they change throughout the year. We can even ask them to do random times so that, for example, a light does not turn on at exactly 9pm every night, therefore providing a layer of security, so that anyone watching might see the house as being occupied.
Duty cycle
Whilst it is not common in all installations, there will sometimes be the need to duty cycle boilers and pumps. The duty cycle is a measure of how long a device operates compared to its rest period. For boilers and pumps, this becomes important when they are likely to run 24/7 in installations that are either commercial or large residential. Rather than using a single boiler that is carrying all of the workload all of the time, which could easily be 24 hours a day, all year, add a second one and you halve the workload.
For context, in the summer, my boiler runs for one hour between 03:00 – 04:00 for hot water. My choice for duty cycle is to use the days of the month so that each pump/boiler combination runs for two weeks at a time. Switching them on and off too often is not good for them either. So, if the day of the month is greater than 15, then switch to duty set two, and if the day of the month is less than 15, switch to duty set one. Achieving that in KNX is a breeze. If you add in fault signals from pumps and valves, then you have an automated switchover in the event of failure. You get an email telling you about the fault, the client does not perceive any change or system downtime, and you look like a miracle worker when you organise for the faults to be fixed that they did not even know they had.
Water
Thinking back to my last article and the holiday home, the automation possibilities there were endless. One area that would have benefitted enormously from automation would have been the watering of the gardens. During our time there, we did not see a single drop of rain – not a cloud in the sky, day after day. The garden was parched – dry as a tinder box. Whilst there was an irrigation system, the On tap was locked away in the plant room so there was no chance for us to intervene.
Add KNX into that conversation however, and suddenly we have a vastly different proposition; we could know and record the temperature, amount of rainfall, and sunlight on any given day. All of that informs a simple piece of conditional logic to say that ‘if it has been hot and sunny for greater than a set time, turn on the sprinklers’. Even at its most basic level, giving the customer the sprinkler On/Off switch on their user interface along with the ability to set a timer would provide a route to solving the problem. As our water supplies are getting more erratic, controlling them surely must be a positive.
Conclusion
Time, or rather timers, is a simple function that we have available in almost any KNX system, but it is often overlooked by the installer. By that, I mean we think it is down to the customer to set them up. Setting them up for the customer, however, is easy, and provides great comfort for the homeowner knowing that lights, pumps, irrigation, etc, are all running themselves. It is such a simple and powerful tool that we should all maximise as part of the final customisation process at the end of a job. Anyone who loves their garden would be delighted to know that they can turn on the sprinklers remotely should the need arise.
Simon Buddle CEng MIET, is a consultant for Future Ready Homes, a specialist in BMS and ELV services system design.
