UKH

The pump packed up on our elderly solar thermal system a couple of weeks back. A local plumber replaced it, but it is clear that the system is very dirty inside and needs a flush.

However, when I enquire of the more specialist companies in the area won't give me the time of day - they are all too busy installing sexy new ground and air source heat pumps for squillions of pounds. Indeed the place who originally fitted the system wanted £225+vat to even come and have a look!

So, would a competent plumber who was used to flushing CH systems be perfectly able to do the same for a solar thermal system? I can't see that the system itself is essentially much different to a CH system, after all. Any pitfalls to avoid?

It would block your U bend for sure. 

If you're is water miscible fluid like mine (glycol) I think you could get away with normal power flush like used on radiators.

Ethylene glycol is horrible for groundwater and illegal to tip down drains. Flushing is easy, but you need to catch the discharge and take it to a tip with facilities to receive it.

Dunno but my mrs was just quoted £500 to have our admittedly grotty but very small and functional central heating system flushed. Bonkers.

jk

many thanks for all the answers. I don't know if the system has glycol in it or not. Sounds like a degree of care is definitely required.