Radiators slow to heat after drain and refil of systme

rb1980 · 30 Jan 2020

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

CBW · 30 Jan 2020

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 · 30 Jan 2020

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 · 30 Jan 2020

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

rb1980 · 30 Jan 2020

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 · 30 Jan 2020

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 · 30 Jan 2020

Ok bet you have dragged some crap through the return filter

rb1980 · 30 Jan 2020

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 · 30 Jan 2020

No clean the filter

rb1980 · 30 Jan 2020

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

rb1980 · 30 Jan 2020

Or you mean the magna clean ?

bazdaman · 30 Jan 2020

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

rb1980 · 30 Jan 2020

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

bazdaman · 30 Jan 2020

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 · 31 Jan 2020

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

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Radiators slow to heat after drain and refil of systme

Similar threads