I am looking to replace the warm air system (J&S) in my 70's detached home (4 beds) and would be grateful for any advice on the best type of system to install. My friend is a property developer and says that I should go for a pressurised sealed system as this is installed in all new homes and does not require big water storage tank and header tanks, etc. - he showed me a system in a new house (tank with a big blue ball on the top). However, an engineer from British Gas said that these are hassle and that we should go for a traditional wet system. I understand that we will need to have a condensing boiler and I have read mixed reports about these too. I am totally confused and really would appreciate any advice. Thanking you very much indeed.