Ok this is really bugging me. After seeing the other post i thought i'd ask as well.

Had a radiator in my dinning room that has never got hot. Recently my dad removed the radiator and flushed it, shook it, swore at it and it was hotter - but not hot compared to the other radiators.

I added radiator flush and left it in for a month (max stated on carton).

removed it at the weekend. drained all radiators and boiler, flushed out the pipes to the 'cold' radiator. one side (return) flowed really freely, the other side (in) the water trickled out of it.

I've now refilled and bled the system and the radiator is barely warm.

Suggestions? i'm thinking its time to rip out the pipe work and refit it from the manifold (where ever that is).

oh, its 8mm microbore and all the other radiators are fine.

Is the pipe kinked anywhere? sounds like something is obstructing it. Are you sure which side is flow and which return as the lockshield valve is on the return side and is set to restrict flow when the system is balanced. Does the radiator get hot where the water comes in when it's switched on or does one side of the piping heat up more than the other?

[Edited on 7/12/05 by Peteff]

pete,

at least you can go into another room !!!

(only joking)

steve

It could be a system balance problem. Try turning down the other radiators and seeing what happens.

Could be a blockage in the pipework somewhere.

Mate of mine had the same problem with his microbore pipe.

Could also be a kink. Can you feel back along the pipework to find out where it becomes hot again?

Mark

Mate of mine had a similar problem the pipe was full of some sort of jelly stuff took ages to flush it out.

Dave

When i did the draining / flushing i had the valves full open on this radiator so i know the 'problem' is further up the pipe!

The inlet pipe does seem to get hot - but heating a inlet 8mm pipe isn't going to be that difficult compared to a double 500 x 900 radiator.

Can't feel back along the pipe as its burried in the wall! looks good - except now when its not working.

As its gone from being warm / hot to cold i suspect a blockage.

was hoping someone would suggest a miriacle cure of doing something silly to move the blockage and hope it sorts itself out....... i guess not

Try banging on the pipe whil flushing. You've probly got mineral buildup in the pipes and banging may breakit loose.

Other than trying a chemical cleaner that will clear the build-up (ask a Plumber) you may have to replace that piping.

I had a similar problem with an old 85,000btu boiler. If its the rad on the end of the system it could just be that your boiler isnt powerful enough. After I fitted a 105,000btu boiler it was red hot

HTH

Don't think its the boiler, its powering 9 radiators and they are all around the same temperature.

(knew i'd find a use for the infra red temperature gun)

They are all 65-75 degrees. This used to be around 35ish, after my dad played around i'd guess it got to 45ish now i'd say its 15 - 20.

Sounds like balance to me, if you turn off all the other radiators and it gets hot then thats the issue.

You balance by selecting the furthest radiator from the boiler and fully open both ends. You then work your way back towards the boiler but leaving the second taps partially open as you proceed (these taps are not just to isolate but also to regulate the flow through). The one next to the boiler will only need to be open 1/2 a turn if that. As you have an infa red gun you can measure the heat loss from entry to exit across it radiator. With everything properly balanced they should all loose the same amount of heat across the front irrespective of size.

If the system is old/blocked you can hire power flush machines from most decent hire companies, these replace either a radiator or better still the heating pump (if its a seperate item and not part of the boiler), you run it for a day and the rubbish you get out will amaze you.

Regards Mark

I'm sure its not balance as its not the furthest radiator in the system.

The others all report similar values with a slight drop (which i'd expect as they are taking heat into the atmosphere).

But the powerflush sounds an excellent plan ........... you guys are the only people who haven't said,

"GET A HEATING ENGINEER IN"

thank god some people are still sane!

Mike, just because it's near the boiler doesn't eliminate balance as a possibility, I have had a similar problem. Worth checking the inlet vs outlet openings on the rad as a precaution before doing another flush..

cheers

Nat

Don't really think it is a balancing problem, mainly beacause you said the water trickled out of the flow or return, regardless of balance the system will be under pressure and you will still get a damn good squirt out of the valve, with 8mm micro bore it is prone to blocking up, you could try a powerflush machine but that MIGHT not work, if the blockage is that bad! it could be a kinked pipe.

As for it now only getting warm...could just be air locked somewhere.

Cheers Mark

defo not a bleed problem (unless there is a kink holding air that i can't get too). All radiators are bled. The boiler manages to heat the other radiators so its doing its job ok. The pump pumps water round the other radiators - so again i assume its doing its job ok.

What i never mentioned previously is i tried locking down all other radiators to force all flow through this one - made no difference and both input and output valves are fully opened.

I would remove the valves from the rad and then try to open them to make sure there is a decent flow. Just because you say they are fully open does'nt mean they are actually working.

Valves where replaced with other ones from the system about a year ago when i put in some thermostatic valves. It made no difference.

I'm starting to think there is some debris in the system and a partial blockage.

By draining the system i've moved the debris up to the partial blockage so now instead of it getting a little warm its got almost no flow.

Is it air locked? Just because you can bleed it doesn't mean it isn't. Likewise if it 'just' flows then it could still be air locked. Turn off the hot water, turn off EVERY rad, but the one that isn't working, turn off any bypass on the heating system, make sure the pump is turned up to Max.

how long do i leave it like that for?

Just worried about over straining the pump.

(have to say i hope it is an air lock, fixing it will be rather easy compared to what i'm starting to dread)

hate to be the one to tell you this, but, if the boiler is firing, pumps running and the other rads get hot......you have tried turning them all off to force the water to the radiator, replaced the valves, drained it and refilled, and water dribbles out of the valve. It is pretty conclusive that the pipe is either blocked or kinked. I would personally repipe the side that the water dribbles out of, pain in the behind but it will be cheaper to get some new pipe than to try flush it, or find the kink (what ever the cause is)

mark

going to give it one last try at putting every bit of water through that rad as i'm sure i left another rad open the last time i tried it. After that ..........

i add another post - how to remove / relay large chipboard floor boards without damaging skirting boards... mumble grumble.

circular saw

and how do i make sure i don't go through any cables pipes etc?

( was thinking about large hole and jig saw but prefered trying to do it properly!)

set the circular saw to the dept of the floor board, go to b&q and measure theres (roughly) then it will just go through, depending on the age of the house the wires SHOULD go trough the mddle of the joists and not on top(through notches). If in doubt borrow a pipe/wire detector for walls, pipes I would think wouldn't really be a problem. Are there any around the area (apart from central heating pipes)

cheers Mark

Chipwood floor thickness either 18mm OR 22mm as said set depth and off you go. If you hit anything sit down and cry.

crying might not be a good idea - water, electrics ........... ooooh could be nasty!

Sort of thinking i'm going to have to lift pretty much the entire spare bedroom floor!

Hot water tank / pump in middle of house, radiator in dinning room under spare bedoom, the pipes go through the walls.

Any hints on plastering ?

Yes get someone in to plaster. It's the only job in the house I can't do. Apart from ironing hoovering etc etc

bugger - we're looking at a 6" by 6' strip. Seems a waste to get someone in to do that (plus damned expensive)

Oi, pipe down at the back, i'm not a tight northern git, i'm merely economical!


Turning all the radiator valves off didn't work by the way. (apart from make one of them leak). Did hear some gurgling type noises as i turned on valves - but i'm taking it so sound more like debris in the water.

Is it T&G chipboard floor? Cut along the centre of a joist and try to miss the nailheads or get a blade that will cut them as well with the blade depth set to 19mm. If you know where the pipework to the radiator is coming from you should be able to pretty much predict the line it takes. Plastering isn't a black art. Just don't try to fill with one coat. Get some undercoat plaster or carlite browning to fill in but leave it low, then finishing with thistle on top. You can mix it thin and paint it on or leave it to go off a bit and spread it on like butter, then finish it with the edge of a trowel before it goes off completely. Dont try to do it with the flat of the trowel or it'll stick and pull it back off the wall.