VAT on Cental Heating Install

[daisy_sb]

I have just had central heating (gas boiler) installed in my residential property. Prior to this I only had electric wall heaters and an immersion water tank which were terrible to run.
What VAT rate do I pay to the contractor? He is supplying materials and installing them.
Will it be 20% or 5%
I read a couple of sourcing that said if a contractor supplies AND installs it is 5% but contractor is saying 20%

[pawncob]

A central heating system may consist of a conventional boiler, radiators, copper pipe, radiator valves, heating controls and so on. Supplied on their own, they are separate supplies in their own right but, supplied together, they form a single supply of a central heating system. While some components of the central heating system may be zero rated as ESMs if supplied on their own, where they are all supplied together they are part of a single supply of a central heating system and, since a central heating system is not included in the list of ESMs eligible for the relief, the whole supply is standard rated.