Weather Compensation

What Is Weather Compensation?

Weather compensation is a communication between the boiler and an outside temperature sensor. The heat we generate to keep our homes warm gets lost through the fabric of the building, and the speed in which we lose it changes depending on the temperature outside. Weather compensation tells the boiler to alter the temperature of the radiators to match the extra heat loss caused by a cold day, leading to a more comfortable and consistent environment.

Having this level of control over your boiler means that it will never generate more energy than what is actually required. This brings with it many benefits.

Weather Compensation Will Save You Money

For most of the heating season the radiator temperature only needs to be a fraction of its maximum output. During this period the weather compensation sensor will maintain the room temperature to be 20 degrees whilst burning a minimal amount of gas. Recently published figures have shown that weather compensation can save you around 30% on your overall gas bills.

Weather Compensation Can Prolong The Life Expectancy Of Your Boiler

When weather compensation is plugged into the boiler, it changes the way the boiler thinks. The aim is for the boiler to operate at the lowest temperature possible whilst still maintaining a comfortable indoor temperature. The boiler will fluctuate the central heating temperature gradually meaning that it doesn’t need to start-up and shut down so often. Constant stop-starting of the boiler takes its toll on its life expectancy. Weather compensation not only creates a more comfortable living environment for us, but it also creates a better working environment for the boiler leading to less boiler repairs and call outs.

What’s Involved With The Installation Of Weather Compensation?

The sensor needs to be installed on a north facing wall so it’s not exposed to sunlight. If north is not possible then north-west is an option, however there other considerations required for this scenario.

There are different sensors available for different scenarios, if the north facing wall is on the opposite side of the building and its impossible to run a cable to it, then a wireless sensor would be a good option. The wireless options are more expensive and wireless technology is not always as reliable as wired technology, so for me, the wired option is my preferred method.

Once connected to the boiler, things are quite straight forward. We simply turn the boiler on and let it do what it’s designed to do. The manufacturers have done all of the science for us and have created different heat curves, all we need to do it set the right heat curve for your property and we leave it alone.

At night we have something called a setback. A setback is a period of time where there will be a reduced target temperature. This is usually around 18 degrees, The important thing to remember is that your house is effectively a heat store, the fabric that your house is made of, will hold heat. If we allow this heat to dissipate, then the boiler will be trying to restore the heat that we’ve lost, instead of maintaining that comfortable temperature that we want. Keeping the setback as close to 20 degrees is recommended, but being warm in your sleep is undesirable, so we must take the re-heat time into consideration.

Once we have found the right setting for your property we leave it alone and forget about it. We’ve been installing weather comp for customers for some time now, and after returning back to the boiler for the annual service, the feedback has always been positive. The savings on the gas bills and the overall comfortability of the house is what customers love to most.

What is a heat curve?

A heat curve is basically a line on a graph, the vertical side of the graph is the radiator temperature and the horizontal side is the outside temperature. You can see from the graph that if it was 10 degrees outside, then our radiator temperature would need to be around 52 degrees, this would maintain a 20 degree air temperature. If the temperature was to increase outside then the central heating temperature would fall according to the set curve.

What if your house has a high heat loss rate?

The previous graph gives you a basic understanding of what a heat curve looks like. Obviously different houses have different heat loss rates. A brand new house for example would hold its heat far better than one built in the 1920’s.
If we only had one curve available then weather compensation would be unsuitable for most houses. So manufacturers give us a few more options, we simply match the curve to suit your properties heat loss, this may take a couple of visits by your engineer. The system is so simple though that this could be altered by the user is needed.


It’s a difficult question to answer because there are many sensors and controls available, but a basic sensor can be bought for around £70.
Basic weather compensation will still need time and temperature control for us to have the setback period required. We recommend using an open therm controller as well as a basic weather compensator to fully utilise the modulating technology. Overall the average cost of materials would be around £200.

Advanced weather compensation controls are available for use with premium boilers, usually these controls come with everything you need in one package.
The total cost of the basic controls is quite similar to the cost of the advanced controls, the only difference is, everything you need is incorporated within the unit.

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