On Thu, 28 Dec 2017 13:12:01 +0000, www.GymRatZ.co.uk wrote:

On 27/12/2017 14:13, Paul Giverin wrote:

What sort of savings would I make with a new efficient condensing
boiler over my older non condensing one?

When I checked my non-condensing one it was only 10% less efficient than
the Carlos Fandango premium condensing boiler by the same manufacturer.

I rather suspect that the efficiency aspect of modern condensing boilers
is rather over-emphasised by the manufacturers choosing to compare under
installation conditions idealised to maximise the performance differences
between the older non-condensing boiler types and the latest all singing
all dancing condensing boilers.

The classic way of exaggerating the difference is to assume a wall
mounted, directly vented to a balanced flue boiler installation in a
modern build house (which is fine if you live in such a modern property
bereft of space and a decent chimney flue to avoid resorting to a
balanced flue).

For those of us living in older properties possessed of suitable
chimneys by which to vent the boiler exhaust and a basement to install a
decently specced boiler into, the improved efficiency in practice turns
out to be a lot less than "The Ideal" case used to justify the extra
expense of maintaining a modern condensing boiler.

If you live in an older Victorian property, as a significant fraction of
households do in the UK, upgrading to a condensing boiler won't
necessarily realise the improved headline efficiencies claimed in the
manufacturers' brochures.

The higher maintenance costs of a modern condensing boiler can all too
readily gobble up the savings in energy costs. When you add in the boiler
replacement costs over the longer term (7 to 10 year life cycles seeming
to be the 'norm' going by posts made to this NG), it would seem that a
good old fashioned cast iron lump of a boiler is a better bet for
minimising the TCO in an older Victorian property.

I'm in no hurry to 'upgrade' the boiler to a modern condensing one just
to reduce energy costs by a mere 10% or less since I suspect the annual
servicing costs will outweigh the energy savings, let alone the fact that
the boiler might not last long enough to realise what savings might
possibly arise in spite of the increased maintenance costs.

My existing 33/34 year old Ideal Mexico Super CF.100 conventional flue
gas boiler has cost me an average of ten quid a year in maintenance
expenses, essentially servicing visits to replace one (possibly two) gas
valve(s) and two (or three) thermocouples with possibly just two or three
cleaning cycles of the burner and H/E assembly. This costing exercise
also included one replacement pump, a 3 port mid position valve
refurbishment, a couple of thermostatic rad valves and a replacement NiMH
backup battery for the Potterton 2000 controller as DIY repair jobs.

The system was installed without a room thermostat, relying completely
on the use of TRVs on all but one rad and the boiler stat. TBH, a room
stat wouldn't have been much benefit in this property and its usage at
the time. Even today, it's hard to make a case for a room stat since it
would require that we elect a particular room to set the temperature for
the rest of the house.

If I was forced to invest in an 'improvement', I'd choose to upgrade the
Potterton controller to a more sophisticated one that includes an outside
temperature sensor for weather compensation and leave the room thermostat
option for later consideration. In my case, weather compensation would
trump a room stat as far as energy savings are concerned in my view.

--
Johnny B Good