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Heating controls on heat pumps and boiler systems – Weather compensation

The Best Domestic Heating Controls for Saving Energy

Like many techniques in building services (electrical, electronics, heating, ventilation, plumbing and drainage), the commercial sector provides guidance and examples on how to optimise your energy consumption to be comfortable, safe, and healthy.

In this article we go beyond the low-cost approach of how to make the most of what you already have and look at what you should have if you replace your boiler or simply want it to help it work less hard, last longer, and save you some money. 

The first step is to operate your system only when you need it and in the best way to save energy. In the UK we have a highly changeable temperate maritime climate influenced by the proximity of oceans, and where the weather can change dramatically over short periods of time. That means it can be warm or even hot one day and then rainy, windy, and chilly the next and, in extremis, the classic 4 seasons in a day. 

The way we do this is by compensating for weather to run the system at the right temperature to suit your lifestyle and budget and, as techniques and technology develop, at the right time to keep costs as low as practicable. This is weather compensation or optimisation. More advanced systems are appearing all the time and some of these help to connect the dots on the ever more sophisticated energy efficiency and cost reduction market.

The next option is to understand how your home heats up when the sun is out or isn’t. Anyone with a south-facing conservatory knows how much heat it can provide on a sunny day. In winter, spring, and autumn or cloudy summer days it can be a boon and will often be enough to keep the whole house warm. On warmer days it can be a pain as you struggle to keep the house cooler than a sauna.

Those who have electric storage heaters will also know the problem of heating adding to the problem when that unplanned surge in sunshine strikes - too hot, uncomfortable, and too expensive. 

Let’s consider 3 levels of weather compensation – “basic”, “better” and “best”.

What is “basic” weather compensation?

Weather compensation is the process of adjusting heating flow temperature with the weather to make the radiators, underfloor and other heat emitters provide only as much heat as each room needs and run the heat source at the lowest possible temperature to achieve this.

Weather compensation is an elegant way of running heating systems. The control system uses an outdoor sensor (on a north wall to avoid solar effects) to monitor the local external temperature. The software learns how your building reacts to heating, how quickly it warms up and cools down, and adjusts the heat source run times and temperatures to provide enough heat when it is required to suit the settings you require.

By running only when needed and at the lowest practical temperature the heat source avoids wasteful and harmful stop/start cycles. This reduces fuel use and reduces wear and tear on the heat source and controls. With the heat emitters only just warm enough overheating is avoided and it is more comfortable – which means healthier. This efficiency means that you can decide how you use the energy budget – more comfort in more rooms, or on other parts of your household budget.

What is “better” weather compensation?

An improvement on the above is to have indoor sensors (it can be one or more to suit your needs but usually a south facing one as a minimum) that register temperature and, optionally, daylight conditions in rooms. This could be included within a zone controller/programmer or as a separate unit. Again, the compensator uses this data to learn how rooms respond in certain conditions and adjusts flow temperatures to suit or holds off the heating. Some systems will have internet connections that are linked to weather data and receive further instructions a day or more in advance to prevent overheating a room or building.

For example, you might set your bedrooms to a minimum of 18⁰C in winter, or lower in summer, and the system will adjust as to whether you need to run your heating to achieve your set comfort level or if the natural environment is going to do it for you.

What is “best” weather compensation?

The next step is to add energy cost controls into the equation. This feature will further improve either of the above approaches to factor in the time-of-day energy cost. This requires an internet connection and probably a subscription to a suitable service.

Some energy suppliers offer this type of service for things like vehicle charging and peak avoidance and the more sophisticated will link this to your systems and equipment to run them or stop them to suit the pricing and demand scenario. A heating optimiser will offer this function for your heating system and link it to the other sensors so that you use your system and buy the energy at the lowest practicable cost for the current and anticipated weather conditions.

You could do some or all of the above manually yourself, especially if you are at home all the time. However, the learning aspect as to how your building reacts is not practical. Choosing the cheapest time to run the system would be nigh on impossible, although standard peak period avoidance is fairly easy to predict. The times that energy is virtually free or ridiculously expensive are available only to professional energy traders with expensive systems and software. By investing in these more sophisticated systems you can be comfortable that you have done all that you reasonably can to minimise your use of resources and the cost of keeping your home comfortable and safe.

Author: FromTheSticks

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