Cheers :thumbs:

take the offending rad off, there is a thread under this one tells you how, take it in the back yard and blow it through with the hosepipe on an outside tap, that will get the majority of the shite out of it, hang it back on the wall, do the nuts up, turn the valves on and bleed it. thats all there is to it

Matt, I noticed one of our rads is doing exactly this, the pipe up to the TRV is red hot, as is the top of the rad but as you work your way across to the other side it gets colder and the return pipe is cold. All the other rads are fine.

We're on an older system with a hot water tank and a Glow worm back boiler, how do I go about flushing/refilling the system on this type of boiler?

Sorry for the thread hijack Ben but it seemed pointless making another.

Combis have a sealed heating system pressureised to 1.5 bar, they dont sludge up often cause no air can get it and the water being pressurised leaves no space for air bubbles, normal systems that have a hot water cylinder are filled by a tank most of the time and have an open vent that goes over the top of the said tank. this vent will let steam out should the water in the system start to boil. The open vent, coupled with the lack of pressure and the increased ability to get small air locks causes open vent systems to sludge up. The fact they are normaly connected to an old cast iron boiler doesnt help. modern boilers have copper or cast aluminium heat exchangers.

once you have flushed out you can add a system inhibitor. its a chemical you add to the water to stop any corrosion taking place, its in the building regs that all new systems have it.

Out of interest matt, is there a way of preventing this sludge buildup? Sounds like an expensive job especially if its easily preventable (for a non-plumber that is, I assume removing the radiators once a year and flushing them out would be the most obvious answer).

I guess I'm asking, as central heating is supposed to be a closed loop system, why does it happen?

If they are hot at the top then they dont need bleeding, air rises to the top causing them to go cool, when they need bleeding.

If its cold at the bottom then they are either sludged up at the bottom, in which case they need a flush, this can either be done with a powerflushing machine, that will set you back about £350 up here maybe more where you are. Or by adding a chemical cleaner, these come in bottles, you add it to the water in the heating via either a radiator or the tank if you have one, they are about £20 a bottle, one will do it. They work well, Sentinol X800 I find is the best. What they do is break down the shit and get it all moving again. you then need to add an inhibitor to stop the problem forming again.

2nd thing it could be is a dying / dead pump. the ones upstairs work ok when this happens because the heat of the water causes it to naturaly rise, the high parts ie the upstairs rads will get hot but the low parts wont, you may get a bit downstairs, like you are

Wont be a pump problem though if you have a combi boiler, it would just knock off as soon as it sensed a problem

Powerflush needed.

Might be worth getting the worse ones off the wall and properly flushed out.

Or do the whole system.

Plumber should be able to flush everything with proper cleaner for about £300/400.

Get a key and bleed them anyway, although I'm certain thats not going to fix it.

i bought an oil filled radiator to make do over winter and my bills went up massively :lol: so fucked that idea off and decided i need to sort the actual radiators out.

Mine are doing the same, tried bleeding and water just comes out instantly... no air.

Gave up and bought an electric heater :lol:

never been flushed since we moved in 3 years ago. unsure how old the system is. the boiler itself is about 15 years old, but works well as the hallway radiator gets boiling hot, as do the other 3 upstairs.

Keys are easy to get hold of. Might help but usually they need bleeding when the top is cold and the bottom is hot.

Usually bottom cold means its full of crap/sludge.

How old is the system and has it ever been flushed as far as you know?

they're about 99p from B&Q etc; the only thing is that if they're aired, normally the bottom heats up not the tops as its the air trapped at the top which prevents the water rising and hence has to be bled out.

I'm sure Matt will be along soon to point you in the right direction

Twist bleed nipple see if any air comes out.

Pipe getting hot before the thermostatic control valve?

You had any of the radiators off to decorate?

Bleeding sounds like a good first step. Your dad will have a key. Some newer radiators have a bit for a flathead screwdriver.

no. been reading a guide which said i need a key, although i don't have one.

have you bled them?

been having this problem a while now, but not really done anything about it.

both the radiators in the living room don't heat up properly. the tops heat up, but the middle/bottom are freezing cold, even when the heatings been on full blast.

the water going to them is boiling hot, yet when i twist the connection on the pipe, before it goes into the radiator, water pours out.

apologies if this is a shocking description. i have literally no idea how to do anything when it comes to plumbing :lol: