IMM wrote in message ...

"Capitol" wrote in message
...

I would disagree about the "ball park figure"
being adequate to start with,

Ballpark is fine. There are a few on-line calculators. It is best to use
a
few. Ad 5 to 10 % extra if you like.

the odds are you will end up with a
boiler and radiators which are too
small.

The smallest of comi's will do the CH on a "very" large house. The boiler
sizing is not a problem if it is not a big house.

Sadly not true, as our friend has found out the hard way!


Of more importance, where are the 10 year
maintenance and running costs factored in
on a combi system without soft water.

Always have a de-scaler on a combi, or on "any" system in hard water.

Combis with descalers in hard water areas, don't generally seem to give 10
years service. All my friends with new boilers are getting less than 10
years life from their modern boilers.



How do these costs compare with a traditional
conventional vented boiler, even allowing
for a tank replacement every 10 years?
Thinking about it, are there any boilers of
any type with a 10 year warranty
even with soft water? In the past, my boiler
life achievements were in excess of 20 years,
have these days gone forever?

Firstly, a combi is a system boiler with a water section. Many share the
same components. Secondly, a combi has most of the "system" in one box.
Only the rads and a wall stat are ouside the box. So when you start
comparing breakdowns and longevity compare like with like. On a
cylinder/tank set up include any problems with the F&E tank, the cold water
storage tanks, the cylinder, the 3-way zone valve, the cylinder stat, the
programmer, all the associated pipework, etc. Then you will find that a
combi is no less reliable, and get a good make of combi, probably far more
reliable overall.

Got it?

Where are the manufacturers offering a 10year warranty?

I had a Potterton Neatheat for over 20 years. The boiler was very reliable
in itself because there was not much in it. In that time I went through 3
pumps, a zone valve, a zone valve motor, a cylinder, cylinder stat, room
stat and a programmer. On the boiler a relay, flue fan and a pressure
differential switch. Overall the "system" was not that reliable. I am
certain a good Vaillant would have given far less trouble over 20 years.

I would regard that as being totally unreliable, only one pump at most would
be necessary on a reliable system.





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Regards
Capitol