We are in the process of buying a house that has been recently renovated. A new Alpha combi boiler has been installed but the old radiators have not been replaced. We have asked to see the commissioning statement for the boiler installation and have been told the plumber is now going back to the house to complete the documentation (shouldn't he have done it at the time?). We have also been informed that the system was not flushed out when the boiler was installed. Is it reasonable to argue that the system should have been flushed out at the time and ask for it to be done as a condition of the sale, or get a quote an negotiate on the price (if so, any ideas on the cost? - would it be cheaper to get new radiators?). The vendor is arguing that the plumber seemed to think the flushing out was not essential, so we should pay to get it done if we think it is "really necessary". I understand it could affect the manufacturer's guarantee.