Cold radiators

[hands2bfree]

Long story ill try to supply all the info:

moved into house - evident the heating had never been touched since 5 years ago when a new baxi back oiler was installed, mix ages of rads throughout the house.

the system is gravity fed

pump working but not sure how to bleed- do i just remove the disc cover?

first, down stairs rad in living room never got hot
second, box room was cold - rad bleed valve was rounded over - so could not bleed system
third, conservatory rad cold.
fourth, dining room and 2 bedrooms rad hot

I replaced the box room rad, but system still same after bleeding

I emptied the system through and filled up + inhibitor.

Still same issue with rads, but with knocking = plumber recommended a solution that that disperses air locks.

poured the solution in and then all rads went cold.

tried heating non stop on high for a few days but no results.

i emptied the system and put clean water in, but still no warm rads.

but i hear knocking again.

any ideas would be welome

 

[tincup]

Hi

What solution did the plumber recommend?
Time for someone who knows what he/she is doing. no disrespect intended.

 

[moggridgeplumbing]

First place I'd check would be the pump. If you want to bleed it on the front is a big silver screw. Loosen it and air may come out plus a tiny bit of water. Does the pump sound airy or bubbily?
Do any of the rads have TRV's on?
As you have already played around with the rads, make sure both sides of each rad that the valves are open. Then you can start to balance the system, but before that answer the above.

 

[hands2bfree]

not sure what the solution was a b&q product

most rads have TPV all valves are open both sides

and the pump does sound bubbily

 

[hands2bfree]

bump