Radiator Problem

adamapple

I've moved into a new property with gas central heating. I have 2 radiators in different rooms which are piping hot near the bottom but barely warm towards the top. I've tried bleeding them but no air or water is coming out of them, so I can't seem get them to fully heat up. Is there anything else I can do fix this? 

Ectophile

If no air or water is coming out, then something is blocking the bleed valve.  Or you haven't opened it enough.

JohnB47

I'm no expert but this normally suggest that bleeding will help, which you've tried. Next, it seems to me a flow issue. So more info might help. Boiler model, pressure level, running temperature etc. Are there rads in a room elsewhere or above - are they OK. Basically more info needed experts to help.

Southend_2

System needs balancing?

ThisIsWeird

adamapple said:

I've moved into a new property with gas central heating. I have 2 radiators in different rooms which are piping hot near the bottom but barely warm towards the top. I've tried bleeding them but no air or water is coming out of them, so I can't seem get them to fully heat up. Is there anything else I can do fix this? 

Photo of rad and valves, please.

As Ecto says, a cold top this usually suggests bleeding is required - ie the top of the rad has air in it - but the fact that no air or water has come out is an issue.

If you show us the valves you have, we can guide you through checking the bleed screw.

adamapple

ThisIsWeird said:

adamapple said:

I've moved into a new property with gas central heating. I have 2 radiators in different rooms which are piping hot near the bottom but barely warm towards the top. I've tried bleeding them but no air or water is coming out of them, so I can't seem get them to fully heat up. Is there anything else I can do fix this? 

Photo of rad and valves, please.

As Ecto says, a cold top this usually suggests bleeding is required - ie the top of the rad has air in it - but the fact that no air or water has come out is an issue.

If you show us the valves you have, we can guide you through checking the bleed screw.

Here's a pic of one of the radiators.

Just to mention I've turned the bleeding screw until it almost came out, but it made no difference.

ThisIsWeird

adamapple said:

Here's a pic of one of the radiators.
Just to mention I've turned the bleeding screw until it almost came out, but it made no difference.

Q - does your boiler have a pressure gauge?

Ok, the valve on the right is a TRV. The one on the left, a 'lockshield'. The lockshield (l/s) 'balances' the rad - it is set and then left.

The white cap on the l/s is probably loose - ie it just spins if you try and turn it? If so, you need to remove that white cap by undoing the screw in the top if one is fitted, or by just pulling it off if no screw. Underneath will be a metal spindle - don't turn this until you've marked its position. You'll need pliers or a wee spanner to turn it.

Mark it either by a felt pen on the front, or by taping a wee paper flag to it. Now turn it clockwise - looking down on it - to shut it off fully. Count how many turns and part-turns this takes, and write it down - you'll want to return it to that position when you've finished your investigation. The l/s should now be off, and the rad not working at all.

Also turn the TRV all the way to 'off' - it, too, should be fully closed, and not allowing water through to the rad.

Now, with a cloth held ready, and towels on t'floor, undo the bleed screw fully - remove it if no water has come out (even tho' the valves are closed, the rad should have some residual pressure in it, so some air or water should come out, but then soon stop).

Q - did any water come out? Any air? Nothing?! If not, try opening the TRV all the way to max, whilst listening at the bleed screw hole. Anything?

If 'no', then close the TRV again, and get a thin bit of wire or similar, around 2mm diameter, and poke it through the bleed screw hole. Don't use anything that could snap or break off! An opened paperclip should be ideal. Anything happen now? If 'yes', then hopefully you've unblocked the bleed screw hole, so can now 'bleed' the rad - but first replace the bleed screw (after giving it a clean - see if it has a slot along its side, if so make sure it's clean) as you'll want to shut it off when it's spurting water!

See how you get on.

Keep_pedalling

Sounds like the bleed valve is clogged up. Try taking the bleed valve out fully and using a needle or paper clip to see if you can clear it.

FreeBear

Piping hot at the bottom indicates that there is some water flowing through the system. If there wasn't any flow, the radiator would be cold all over.

First thing to check is boiler pressure and top it up. Bleed a few other radiators to make sure that water is in the system and you can get an idea of how far to open the bleed valves. If still no air/water coming out of this radiator, you may have a gummed up bleed screw. If this is the case, it might pay to replace the vent plug & screw - One of these will do the job as long as your radiator has blanking plugs either side -> https://www.screwfix.com/p/essentials-radiator-vents-blanking-plugs-nickel-2-pack/40972 - A word of warning. You'll want to drain a bit of water out of the system first. Take the opportunity to add some corrosion inhibitor when the system is refilled.

Grenage

I've had this with a radiator once, and pushing a bit of wire through the bleed valve did the job.

Bigphil1474

I had this with a radiator in our old house, in the attic, the radiator was only hot for the lowest few inches. Opened the bleed valve, a little puff of air and then nothing. Whilst on the phone to the in law plumber, he told me to top up the system to a little bit higher pressure than normal using the two taps in the airing cupboard in the bathroom, then fully open the bleed valve in the attic, if no water appeared, close it again, go down to the boiler, check the pressure had gone down, up to the bathroom to re-top up the system, then back to the attic and try again etc. repeated about three times before any water came out of the radiator bleed valve. After that it was bob on. Good exercise too.