Donald Hutchison

I jointly own a rental property with my spouse. As part of the pre-letting work on the property we replaced an aging gas boiler with a new unit, and this is being financed by a 4 year interest free loan from British Gas. As a like for like replacement, should we claim the sum of the monthly payments made during each tax year until the loan is paid off, or the entire cost of the replacement boiler in the current tax year?