You don't need planning permission to install a ground or air source heat pump provided that any top soil that's removed is re-instated to its original land level and that your 'permitted development' rights have not been removed by a condition on a previous planning permission.
Bye-laws note: you'll need building bye-law permission to install ground and air source heat pumps except where the work is undertaken by an approved competent person and the department is notified of the works within 30 days prior to completion.
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