blocked radiator

[johnscales]

I know this has kind of been done to death as part of a system flush as this is all i find googling the web but i'd like some advice/opinion on what good methods there are for flushing an individual radiator.
Just some background:
I've flushed my system and after reintroducing the water supply bled all of my radiators in turn. One radiator however hissed out some air as per normal then went quiet. I waited a while the removed the bleed nipple until it came out of the radiator. Still nothing. The rad warmed slightly up to about a quarter of the way up and stayed cold the rest of the way. I had thought that this rad had a problem with the trv before but now i'm convinced there's a blockage. Oh yeah, I replaced the bleed nipple BTW.

 

[johnscales]

Oh and I should also add that I took the rad out and ran the hose through it until clear so whaat i'm getting at is how to flush out the rad channels.

 

[1john]

Have you tried shutting down all of the other radiators?

 

[johnscales]

Nope but can try in the morning (needed to have some heat in the house tonight or there'd be complaints).
I'm thinking it won't make any difference unless you're thinking along the lines of the affect being to increase the pressure to that radiator and hopefully helping to push the blockage along. Can you confirm?

 

[1john]

either move a blockage, or more than likely an air lock, just show down the trv's on every rad and have the non-working one fully open, it wont take you long.

 

[johnscales]

In case it makes any difference it's the first rad in the circuit. All other rads are hot.

 

[johnscales]

Cheers 1John. Will try this in the morning.

 

[JohnD]

did you clean the syatem using a chemical? if so, which one, and for how long?

 

[johnscales]

Sentinel x400 twice this year (first time was because I messed up a standard drain down and the second time 2 months ago. Todays drain down produced lots of black stuff .

 

[JohnD]

... and for how long?

 

[1john]

Is it a sealed or vented system?

 

[johnscales]

JohnD 1st time for 4 weeks before introducing inhibitor. 2nd time 2 months as I introduced the inhibitor today.

1John - vented

 

[JohnD]

JohnD 1st time for 4 weeks before introducing inhibitor. 2nd time 2 months as I introduced the inhibitor today.

Just to check

you mean you put in X400 and ran the system for 4 weeks before draining and rinsing; and then again for 7 weeks before draining and rinsing and adding inhibitor?

Have a look at the feed and expansion tank in the loft and see if water comes out of the vent pipe (bent over the F&E) when the system is running. It sometimes makes a difference if HW and/or CH is on.

 

[johnscales]

Will do in the morning JohnD. What conclusion do I draw if water does come out of the vent pipe whilst the system is on?

 

[JohnD]

that is called "pumping over" and it constantly introduces dissolved air into the circulating water, which causes corrosion. If so, it has got to be fixed. Sometimes it is caused by incorrect design and build, and sometimes it is caused by sediment blockage in pipes, which X400 will sometimes clear. If you have got a lot of black sediment in the system (flushing never gets it all out) it is worth investing £100 in a Magnaclean. I guarantee you will be amazed and delighted to see how much sludge it traps.