Radiators slow to heat after drain and refil of systme

[rb1980]

Hi all had to drain and refill a pressurised system after using x400 .since refil it seems I don’t get as much flow to the radiator and one just won’t get hot at all .. have bled it and have also done so by taking out the entire bleed valve , turning each side of the rad off and bleeding both lock shield and trv side . I just think the flow from the boiler is now slower .
Any ideas ? Systme bled etc .
How fast should the pump be spinning ?
When i 1st refilled and turned on i got a pump fault light and some gurgling but that cleared songuess was air

 

[Deleted member 267285]

• What boiler is it?
• What do you mean by you don't get much flow?
• Have you imbalanced the system?

Some pumps are single speed and others are variable, so depends on the boiler/pump, hence which boiler is it?

 

[rb1980]

Main 28 he
Before you could hear the water running fast through the radiator . Same with my underfloor heating the system would get better flow as Indicated on the flow meters , hard to explain but I know it’s running slower for want of a better decritpion .

 

[ianmcd]

Did you close the Lockshield valves when you were cleaning the system ?

 

[rb1980]

Nope they’re all open returned to what they were pre the clean , have fully opened them on the cold radiator but still Luke warm .the flow and return pipes going into the radiator are nice and hot though ...

 

[blubs]

turn pump to max, close any bypass, try heating without hot water, water without heating, , turn off all radiators but one, do this all round the house, look for air release valves, tap auto ones (undo plastic cap, this shouldn't be tight),, bleed manual ones, bleed pump, bleed rads, check rad valves are open .. keep doing these things hopefully you'll hear some glugging and sloshing and bingo, your back in business, its very common, if you have TRVs , take the heads off and check the pin underneath pops down when you push it with something, if not , lift it up a feww mm to free it.. good luck..

 

[bazdaman]

Ok bet you have dragged some crap through the return filter

 

[rb1980]

Thanks to both bled the boiler pump , it has an auto air vent , screw wasn’t tightened down . All but one radiator gets hot . I think there’s still a bit of air as I hear the occasional noise of it now and then in the “working “ radiators .
Have bled the trouble rad twice now by taking out the bleed vent . Adaptor and Hose on the end , open and close lockshoeld/ trv side alternately.there were some black Bits floating in it . Flow and return are both hot on the rad . All other radiators working fine .

Bazdaman do you suggest another flush with chemicals drain down etc ?
Cheers guys

 

[bazdaman]

No clean the filter

 

[rb1980]

Ha yes I guess that’d prob help .
Where is it located ?

 

[rb1980]

Or you mean the magna clean ?

 

[bazdaman]

There is a gauze filter in the return isolation valve on the boiler

 

[rb1980]

Ah right , how much of a pain is it to get to dnd clean ?

 

[bazdaman]

Easy enough, isolate flow and return and crack the nut on the end of the return iso, the gauze is in there, check in the manual for detailed instructions and location

 

[rb1980]

Sorry , excuse my ignorance but what does crack the nut mean ?
Prob a dumb question lol