On Jun 5, 4:03*pm, YAPH wrote:
On Sat, 04 Jun 2011 16:09:15 -0700, Tabby wrote:
plain pump:
so a 30w non-electronic pump will use about £3.30 per yr in leccy, £33
per decade, £83 per 25 year CH system life

Screwfix Flomasta me-too B-rated pump costs £40, uses 52W on setting III,
40W on setting II - let's assume we use this setting

TCO per 25 yrs is thus £25+£83 = £108

£40 + £110 = £150

smartpump:
vague guess halved energy use - £42 per 25yr life TCO thus £126+42 =
£168

Wilo A-rated smartpump is £65 at Screwfix so £65 + £55 (same guess: half
the consumption) = £120

Yes, reading a bit more I saw they were around £65. But also that
energy saving is *upto* 50%, and since one must inevitably use just as
much energy to pump when the boiler is at max output, IRL the energy
saving is 0-50%, which we could guesstimate as 25% average save.

Pasting previous revised calcs...

plain pump:
so a 30w non-electronic pump will use about £3.30 per yr in leccy, £33
per decade, £83 per 25 year CH system life

TCO per 25 yrs is thus £25+£83 = £108


smart pump:
Energy saving 0-50%, so approx average 25% saving
£83 thus becomes £62 per 25yr life
TCO thus £65+62 = £127


However the revelation the 40 or 52w figure will change that again.
OK, I'll revise the above...

plain pump:
so a 40w non-electronic pump will use about £4.40 per yr in leccy, £44
per decade, £110 per 25 year CH system life

TCO per 25 yrs is thus £40+£110 = £150


smart pump:
Energy saving 0-50%, so approx average 25% saving
£110 thus becomes £82 per 25yr life
TCO thus £65+82 = £147

So no saving, but more upfront cost.


NT