Boiler and rads advice please

wittymoniker

G'day, I'll be starting a renovation/extension shortly and would like a bit of guidance on my heating options. I want mains gas with rads and two pumped showers with a backup electric shower in the downstairs wc.
So, from there on I'm all at sea.
Will a combi run all that to a satisfactory performance? I'd like not to have a DHW tank. If so, what type/output? If not, what are the standard condenser boiler recommendations?
I'd like a few feature rads in the downstairs rooms, cast period ones maybe, are they going to be harder to run than modern ones? On the subject of modern rads, what are the type to go for these days? Roll top, pressed, double/single, fancy designer ones? Is there a big difference in performance?
The house will be about 2500 square feet, 4 bed, 1 bath and 1 ensuite, well insulated and not exposed.
Many thanks for any assistance.

heinbloed

Neither the house is designed nor the heating system.
A combined aproach is what the building regulations ask for. And what is logical.
Ask the architect/plannner to do a heating energy demand calculation according to EN12831. Or similar, signed and sealed.
Without knowing the demand no one can give a serious answer to your question.

mark_18tp

this is my view on it.

dont get a combi. get a good system boiler and a unvented hot water cylinder. if your mains is poor install a booster pump

radiators. if you like the older cast iron one then get them, have a couple at its nice that when you turn the heating off the hold the heat for a while. if you what more efficient radiators then alumimuim radiators are the best more expensive but heat up times are v.fast

plumbing as above unvented hot water cylinder mains pressure and as above if incoming mains poor install a booster pump