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Weather compensation

Is there anything us Brits like more than talking about the weather? It’s more than just a stereotype, it’s a national pastime! And thanks to our understanding of climate change globally, talking about the weather has become more than just small-talk. Regulating the temperature inside your home is now vital in stabilizing the global weather outside your door. If we are to meet our carbon reduction target of net-zero by 2050, then energy efficiency is key. So today we’re looking at how weather compensation devices can keep you comfortable when it’s ‘absolutely Baltic out there’, whilst saving you money, and reducing your carbon footprint.

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Is there anything us Brits like more than talking about the weather? It’s more than just a stereotype, it’s a national pastime.

And it’s not just a polite ice-breaker either, studies have shown that we spend six months of our lives talking about it.

And thanks to our understanding of climate change globally, talking about the weather has become more than just small-talk.

Regulating the temperature inside your home is now vital in stabilizing the global weather outside your door. If we are to meet our carbon reduction target of net-zero by 2050, then energy efficiency is key.

Since April 2018, all new boiler installations have had to use one of four energy saving features – one of which is weather compensation – which is ideal for a country with our changeable weather.

So today we’re going to talk about how weather compensation devices can keep you comfortable when it’s ‘absolutely Baltic out there’, whilst saving you money, and reducing your carbon footprint.

Weather compensation and Boiler Plus

Diagram showing Boiler Plus.What does Boiler Plus say about weather compensation?

There are many different types of central heating controls available, all of which can all help to improve your boiler’s performance; increase your comfort; and save you money.

The Boiler Plus regulations require that all new combi boilers must have one of four requirements fitted:

The Heating People favour weather compensation over the other options because it offers the biggest efficiency gain and is a simple technology to integrate.

ATAG boilers come with weather compensation as standard, which is one of the reasons we love them.

What is weather compensation?

Two rain clouds.The Heating and Hotwater Industry Council (HHIC) defines weather compensation as:

“a control function which maintains internal temperatures by varying the flow temperature from the heat generator relative to the measured outside temperature.”

In other words, weather compensation devices monitor both the temperature inside your home, and the temperature outside, and adjust your boiler’s operation accordingly.

The reason that the outside weather matters when it comes to heating your home; is because the heat we generate to keep our homes warm gets lost through the walls and the roof; and the speed in which this happens will depend on the temperature outside.

On a cold day, the heat will be lost more quickly than on a warm day. To find out more about this, you should read our blog: What is heat loss and why is it important?

A weather compensator tells your boiler to increase or decrease the temperature of your radiators to match the heat loss caused by the weather.

So, instead of your boiler switching on or off depending on when your home gets too cold or too hot, weather compensation will monitor and maintain your chosen temperature without having spikes of over and underheating.

Why does weather compensation keep the heating on at a low level?

A cold woman thinking about the weather.At first it might seem counterintuitive to have your heating on at a low level all the time; in order to save energy. But it’s a bit like driving your car at a steady 50mph…

Whilst you might want to put your foot down to get to your destination quicker; you would use far less fuel over the course of your journey; by driving at a slower pace; with fewer variations of speed.

Weather compensators work in a similar way.

The weather compensation control runs the boiler at as low a flow temperature as possible; whilst still providing enough output to the radiators to maintain your chosen temperature.

You’ll have a more comfortable and consistent environment without your heating cycling on and off. And by running at a lower flow temperature; your boiler’s operation in condensing mode is optimised. It will never generate more energy than is needed.

Not only will this save you money on your energy bills, but it will reduce your carbon footprint too.

How does weather compensation improve energy efficiency?

The reason weather compensation is so efficient; is because modern condensing boilers are happiest when the central heating system runs at lower temperatures.

Many boilers never achieve the sweet-spot in condensing mode, as the operating temperature is set too high.

Weather compensation allows your boiler to reduce water temperatures, which increases efficiency without compromising your comfort.

You’ll be more comfortable because your boiler will be able to maintain a steady internal temperature; by adjusting boiler output to account for the weather.

How does weather compensation work?

A diagram of weather compensation.Weather compensators work in a more straightforward way than you might expect. We’ve broken it down into five steps for you:

1. An outdoor sensor measures the outside temperature

An external sensor (which can be hard-wired or wireless); may need to be installed on a north or west facing wall. This measures the outside temperature. However, many smart controls can now use GPS weather-data to provide the same functionality; without the need for an external sensor.

2. The temperature reading is sent to an electronic controller.

The temperature readings taken by the external sensor (or from GPS weather data) are sent to the weather compensation controller.

3. The temperature controller calculates the heat supply needed to maintain a steady temperature.

The weather compensation controller looks at the outside temperature, and the temperature you want your home to be. And runs the boiler at as low a flow temperature as possible; whilst still providing sufficient output to keep your home at your chosen temperature (normally 19-21 degrees).

Running the boiler at a lower flow temperature helps to optimise its operation in condensing mode. Think of your car doing a consistent 50mph –  saving energy and maximising boiler efficiency.

 The controller automatically knows what temperature the boiler needs to flow at to get to and maintain your chosen temperature.

4. If required, the controller will adjust the boiler heat supply to the radiators.

Not only does the controller know what temperature the boiler needs to flow at; it then automatically adjusts as the temperature outside or inside changes. The controller alters the boiler flow temperature as soon as the outside temperature changes.

If the temperature outside rises the boiler reduces its output; and if it drops; the boiler increases its output, to match the heat loss.

This avoids the situation sometimes experienced with conventional room-thermostats; where your home gets too cold or too hot; before your boiler receives a message from the thermostat.

5. The system records both indoor and outdoor temperatures so it can fine tune its adjustments.

Weather compensators also record data on the indoor and outdoor temperatures; so they can learn about how quickly your home loses heat in different weather conditions. This means that the controller can fine tune the instructions given to your boiler; on how much heat to generate; and for how long.

What are the benefits of installing weather compensation devices?

There are lots of advantages of installing weather compensators. Here are just a few:

Weather compensation is low maintenance

The beauty of weather compensation is that you don’t have to lift a finger. The temperature controller does all the sensing and calculating of the required temperatures; and gives the instructions to the boiler. All you’ll notice is a comfortable home, whatever the weather. 

Weather compensation can be left on all year round, only firing up when it is needed.

Once installed, you really can just forget about it. Your weather compensator will only fire up your boiler when it’s needed.

Weather compensation can save you money

According to The Energy Saving Trust (EST), the cost of heating a home; particularly during the colder winter months; makes up about 60% of household energy bills.

Weather compensation systems can lower your fuel bills. Because they help your heating system to work more efficiently, reducing fuel usage.

And with the current price of gas, that’s got to be a good thing!

 With a boiler flow temperature being kept as low as possible, around 55°C or less; the boiler can condense as it is designed to; running more efficiently; and saving you money.

BEIS found that bill savings from weather compensators varies from home to home. But the greatest savings are for households with the highest bills in the first place.

Viessmann conducted research at Salford University. They found that a simple weather compensation sensor typically saves the householder anything from 10-30% off their energy bills. This equates to a good £40-£100 or more per year.

A report by an environmental science consulting group; published similar estimated energy savings. They say the savings are between 10-40% for electronic weather compensators in one-family houses.

You might like our related blog: Does smart heating save money?

Weather compensation reduces your carbon footprint

According to the Climate Change Committee (CCC), energy use in homes accounts for about 14% of UK greenhouse gas emissions.

These emissions need to fall by at least 24% by 2030; from 1990 levels; for us to meet our national target under the 2015 Paris Agreement.

In response to this, and as part of the Government’s ‘Heat in Buildings’ programme; Boiler Plus was created to maximise energy efficiency in homes from April 2018.

Fitting weather compensation technology, is one of the four ways to comply with the energy saving requirements for new combi boilers.

This is because most of the time; your radiator’s temperature only needs to be at a fraction of its maximum output; to keep your room temperature just right. Any degree above what is actually needed, is just a waste of energy.

Weather compensation avoids wasted energy. Because it instructs your boiler to burn a minimal amount of gas to maintain your chosen temperature.

Burning less gas means that less carbon dioxide is being emitted, and thereby reduces your carbon footprint.

Weather compensation provides a more comfortable and consistent environment

Since weather compensation keeps your home at a steady consistent temperature, you’ll benefit from increased levels of comfort.

Weather compensation is a proactive approach to your heating. It alters the radiator output before the house drops in temperature. Whereas a conventional system only notices an increased demand for heat after the room temperature drops.

So, no more feeling cold waiting for a reactive system to catch up. With weather compensation, you won’t even notice that it’s started snowing outside. 

Weather compensation avoids spikes in over and underheating.

Weather compensation technology keeps your heating system on all the time at the lowest level possible; instead of it being continually switched off and on by a timer and an indoor room thermostat.

Although keeping your heating on all the time, sounds less energy efficient, this isn’t the case.

We’re back to the example of keeping a constant lower speed on the motorway to save fuel.

Keeping your heating on at a low level; is much more energy efficient than your heating ‘cycling’ off and on all the time. Because your boiler isn’t working hard to heat your house from a completely cold start once or twice a day.

Instead, your heating system will constantly be reacting to gradual temperature changes outside. This allows your home to always be at the right temperature, without over and underheating.

Weather compensation can improve the lifespan of your boiler

Avoiding boiler cycling (through proactive weather compensation) can also prolong the life of your boiler.

This is because your boiler will always be gently ticking over at the lowest temperature possible. And it isn’t having to start-up and shut down so often.

Constant stop-starting is tiring for anyone, and the same is true for your boiler.

Weather compensation not only creates a more consistent home temperature for you; but it also makes life easier for your boiler, meaning break-downs are less likely.

Weather compensation is quick and easy to install

Weather compensators can be quick and easy to install. Once connected to the boiler; your engineer will set the appropriate heating curve from the options supplied by the manufacturer. And the technology will do the rest.

How is weather compensation installed?

If you’re installing weather compensation with an external sensor (rather than one that uses GPS weather data); then a sensor will need to be installed on a north (or possibly a north-west facing wall).

The sensor is wired to the internal controls of your boiler; so that it can communicate instructions on how much heat to generate (and for how long); depending on the outside weather conditions.

The instructions are based on a heat curve which will be set by your engineer.

The heat curve determines what temperature your boiler should heat the water to, at a particular outdoor temperature.

This is shown with a line on a graph. The vertical side of the graph is the radiator temperature and the horizontal side is the outside temperature.

Your engineer will choose the right curvature to maintain the same temperature inside the building at different outside temperatures; using the manufacturer’s instructions; and the heat loss calculations taken from your home.

When it gets colder outside, the controller automatically raises the boiler water temperature, which prevents your rooms from cooling down.

What if my home has a high heat loss rate?

You don’t need to worry about whether or not your home has a high heat loss rate. Weather compensation will still work for you.

Different buildings will have different heat loss rates depending on factors such as their insulation and glazing. To find out more, read our blog: What is heat loss and why is it important?

A brand new house will hold heat for longer than an old house built in the 1900s. This isn’t a problem because manufacturers of weather compensation devices create different curves for different homes.

Your engineer will  match the curve to suit your properties heat loss.

Weather compensation – final thoughts?

Weather compensation is a brilliant way to improve the efficiency of all heating systems. And offers extensive benefits to all homes.

But precisely how much you stand to gain from a weather compensation system will depend on your individual circumstances.

The HHIC says that systems using weather compensation generally perform best where continuous heating is being used; or for an extended period “once” a day.

So, if you’re at home a lot throughout the day; you’ll obviously benefit from the consistent temperatures, more than a person who is out at work all day.

Temperature sensitive occupants such as babies and the elderly might also benefit significantly from having a consistent, constant temperature.

In terms of monetary savings; research suggests that those with the biggest bills to begin with, will see the biggest reductions by using weather compensation.

But whatever your situation, weather compensation will:

  • create a more comfortable and consistent living environment;
  • prolong the life of your boiler;
  • save you money on your fuel bills;
  • and reduce your carbon footprint.

So, we should all be using the weather to our advantage. Now that really is something worth talking about.

Useful Links:

The Independent article about Brits talking about the weather

Boiler Plus factsheet from the government

Boiler Plus consultation reponse

The Heating and Hot Water Industry Council article on weather compensation

Government report on compensating heating controls

Energy Saving Trust article on heating and hot water