The saga of Mr 'two pumps' Gazz's motorhome CH system got me wondering:
where do you get 12V or 24V DC circulating type pumps from, and a bnus
question for 10: how much do they cost?

Alternatively is there a cheap ( 100 ukp) off the shelf CH circulator
with electronic speed control, or a cheap off-the-shelf variable speed
controller suitable for driving CH circulator type motors?

(The requirement is to drive CH primary water through a plate heat
exchanger at variable speeds up to somewhere of the order of 30
litres/minute. Google throws up lots of diddy pumps for water-cooling PC
CPUs and a few industrial-type things.)