As it would need to be fitted by a Hetas registered installer, you might be better of to get one of their guys to take a look.
They will assess what you can or cannot do, plus a cost for doing it.
You can go down the diy route, but need to inform bco and pay their fees, get it all signed of and certificate issued.
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
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