That's not what you said initially!
Sounds like it is a Y-Plan system - which already has all the necessary boiler interlocks. But, AIUI, TRVs will be *required* - rather than optional - to meet current regs.
Cheapest way.......Do it yourself. Saves a fortune! Spanner monkeys an sparkies always charge a fortune for shoddy work! That f**cks me righ off
-- Part P Avoider
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