Heating Advice

It is difficult to give definitive advice, and you do not mention whether the boiler is being changed anyway – or if the solar system is proposed instead of having a new boiler. Also it is not clear whether the existing boiler is a combi (heating water on demand) or a conventional boiler (with hot water storage cylinder).

A condensing boiler (whether combi or conventional) is now required under Building Regulations for new or replacement heating systems, and will offer fuel/cost savings due to its greater efficiency.

The solar system will (as you imply) only provide hot water. If a solar system is being considered it is, in many cases, better to design a complete package so that the solar panel is correctly integrated with a storage cylinder (twin coil type) and condensing boiler, using an appropriate control system so that the full benefits of the solar heating can be achieved. Many major UK boiler manufacturers now offer such “packages”, although these come at a cost!

Inappropriate “grafting on” of a solar panel to an existing system may not be effective, may affect the rest of the heating system and may not justify the costs involved.

While you may wish to consider the environmental benefits, it is important also to consider the “payback” for the solar system against the savings from just changing the boiler for a more efficient type, improving the controls (using TRVs and weather compensation controls), and improving home insulation – which will also greatly benefit the environment.

I cannot give direct cost benefits as this depends on the relative costs quoted for boiler replacement and for the solar system proposed, however I hope this helps.