New Legislation When Fitting a Combi Boiler

As from April 2018 there will be new rules that must be followed when installing a combi boiler in order to comply with new government legislation in the UK. The reason being the current regulations came about a long time ago and there is new technology out now that makes heating your home and hot water even cheaper. The main aspects of the new legislations means that one of the following needs to be installed when fitting a new combi boiler.

  • Flue gas heat recovery systems
  • Weather compensation
  • Load compensation
  • Smart controls featuring automation and optimisation functions

I’ll briefly explain what these four different options are.

Flue gas heat recovery systems – This is another heat exchanger that would sit on top of your boiler, and would extract the very little heat from the fumes that go through the flue of the boiler. This heat exchanger would then apply that heat to the cold water inlet of the boiler.

This flue gas heat recovery system takes up a lot more space and costs around £500 / £800 plus fitting. Not exactly my first choice.








Weather compensation – A weather compensator would be an additional feature of your heating controls (timer). This would measure the outside temperature, using a sensor or online information and switch your heating on later on a warmer day and earlier on cooler days. These can vary in price depending on the boiler you have.

Load Compensator – This means the boiler would increase the water temperature in your radiators when the house is cold and not so much when the house gets warmer. As far as I’m aware these are only available when you use certain boiler manufacturers own more expensive heating controls on their own boilers. Alternatively if you have a boiler and heating control that supports OpenTherm then this would compensate the load, however this is very rare at the moment. Again, as far as I’m aware only certain Ideal and InterGas boilers currently have OpenTherm.

Smart controls featuring automation and optimisation functions – There are a lot of ‘smart’ heating controls available at the moment however, the only ‘smart’ control that would not only provide automation and optimisation functions but would also act as a weather compensator when connected to the internet, and a load compensator if installed with an OpenTherm compatible boiler would be the Nest Learning Thermostat. The Hive, Tado, Salus and all the others do not work like the Nest.

Even though the Nest Learning Thermostat can be used with an internet enabled device the Nest will save you money because it automates your heating. What does that mean? As the Nest has a motion sensor built into the device if the Nest does not see any movement for a while then it won’t switch the heating on. What it also means is you would never have to programme the heating schedule again. All you would do the 1st few days you have the Nest is to turn the temperature to your preferred temperature when you are home and when you are away or in bed and that’s it.



The Nest Learning Thermostat can do a load more stuff, too many to mention in this blog so I’ll just say The Nest or the Nest E (cheaper version) really is the best there is for most boilers. The Nest can be fitted to any heating system, not just combi boilers. The Nest will make even the oldest boiler a lot more efficient. Your standard heating controls would be charged from around £50 upwards. To have a weather compensator fitted could cost an additional £60 plus depending on the boiler. The Nest currently cost £200 and the Nest E will be cheaper when it is available in the UK. Fitting a Nest control to a combi boiler would be my first recommendation because they are easy to fit and comply with the new regulations.  

For more information on how to get a new boiler or better heating controls feel free to contact Pavlou Plumbers.


Here’s a picture of Louie because he’s ace!

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