Hi,
I have a 22 year old 15Kw Potterton Suprima 50 which has served our needs over the years powering 12 radiators, 4 bedrooms with a bathroom and en suite. I'm looking at replacing it with another 15Kw eg Worcester Greenstar but it recommends it only up to 8 radiators. So my question is, is there any difference in performance with a modern condensing boiler (ie worse) compared to my old non condensing boiler? We've never had a problem of not enough heat / hot water from our 15kw boiler.
I'm trying to avoid jumping up to 18Kw because we only have 15mm pipes and don't want to have these updated to 22mm if i can avoid it.