can anyone point me in the direction of a switch that I can add into my coolant system that detects flow. I'm not sure if it would be called a flow switch, flow sensor or something else entirely.

basically I plan to remove the mechanical pump and replace for an electric one but want something that confirms the electric pump is working.

if it helps my coolant system is in 25mm hose.

Thanks

You could use a differential pressure switch which powers an indicator lamp?

Plenty of flow switches in central heating systems which would be happy under pressure and getting toasty warm. Not sure many are in-line mind....

funnily enough im looking at central heating systems, but the best I could hope for is 22mm in plumbing stuff, I dont think anyone uses (or if it even exists) 25mm

Thanks

http://www.bes.co.uk/products/142b.asp

one of these fellers at the bottom?

Mmm sounds like something in a combi boiler might do the trick. they have a flow switch I am sure.

Any heating engineers confirm this???

Stick with the reliable mechanical pump. Don't bother with a "Craig David"

You could monitor current drawn by the pump motor using a ct and a bit of electronics, save putting something in your water system