In article ews.net,
"Doctor Drivel" writes:

No CH pump fail? After how many years? I have seen one Grundfos going for
15 years on the cooler return with a weather compensator on the system. The
return was always very cool. And it has a filter on it and always had
inhibitor too.

Parent's central heating pump did 43 years and was still working
fine when removed. It was a Sigmund, bought in the 1950's. It's
coil burned out shortly after their mains voltage changed from
200V to 240V in 1960, and my father fitted a new coil (which you
could do without draining down). The pump ran continuously on
their system, 24x7x365, which is nearly 400,000 hrs. A plumber
who came and replaced the hot water cylinder on some occation
when my father was abroad commented on the pump, saying never
to chuck it out, as those pumps never die. It outlasted a
couple of boilers, and might still have been working today if
it hadn't been removed when a small wallmount boiler was fitted
in 1999.

--
Andrew Gabriel