Pricing a job for a customer for a new boiler and a few additional rads, all the existing rads plus the new ones come to approx 25Kw in total. I was going to go for a 28Kw Vaillant open vented boiler. 25Kw seems to be cutting it a bit fine. Next boiler up is 38Kw, however vaillants can be range rated to suit. What do you guys think? Will it be enough or will I just go for the next size up? The cylinder coil is not included in the 25Kw