John Rumm wrote:
On 12/03/2011 14:49, Andy Dingley wrote:
On Mar 12, 10:30 am, "Dave Plowman
wrote:
combis are the way to go.

Maybe if you don't have a bath.

Rubbish, and has been for decades.

We're running what might be the world's oldest Worcester Bosch combi
(there's a plaque on it from the Newcomen Society) and that fills a
bath just fine. Sure, the first combis had capacity problems that made
them a problem for filling baths, but that's way in the past now.

The usual problem is people buying on price and installers under
speccing them.

Calculate what e.g. a 500 mains pressure liter tank fitted with twin
22mm feeds to two baths can do in terms of hot water flow rate: then
calculate how big a combi you need to match it.

Now calculate which costs more, and takes more space...and will be less
efficient as a central heating machined because its wildly over specced
for that purpose.

Combis are, basically, rubbish. Any attempt to make them work
adequately, makes them bigger, more expensive, and less efficient than a
system boiler + PHW tank..