Old system playing up

[Last Plumber]

Thank you, what about cleaning or is a flush through with fresh water a couple of times normally enough?

I would put F3 Cleaner in, leave it a few weeks, Get it hot and empty it. Then refill, dose with F1 and Balance !

I would do this after the pumping over the vent pipe has been dealt with though otherwise, you'll be wasting your efforts.

 

[ShaunCorbs]

Ah!
Another amazing invention.
They would all outlast any modern effort!

Yep had one had to get rid flue was smelling a bit

Even had the upgraded cast hex, it's in the local tech collage now

 

[Last Plumber]

Yep had one had to get rid flue was smelling a bit

Even had the upgraded cast hex, it's in the local tech collage now

See....it lives on...even wounded!
Warriors !!

 

[Ric2013]

From the instruction manual, the heat exchanger looks to be cast iron. Certainly the Potterton Netaheat Profile, later renamed simply 'Profile' has a cast-iron heat exchanger.

Re water pouring into your cistern, you mean the hot water comes out of the vent pipe over the top of your feed and expansion system and runs into the cistern? A run or a dribble? Does this continue to dribble when the system is good and hot and has been running for some time?