Why is only the top third of my radiator hot? <Brrrrr>

[winnybella]

It's an old, cast iron radiator. I thought it needed to be bled, but then DP started wondering why it's the bottom two thirds that are cold. I would think that the air would have risen to the top?

Anyone knows? There are two valves but they are painted shut so we want to be sure opening them up will help iyswim. TIA

OPen them, you have air in the system, you'll need to do them all. HTH

You need to bleed them.

Sludge

Air or build up of sediment. I would bleed and if that doesn't work you may need a plumber.

i second getting air out. remember to get a tea towel or summit, if old will have rusty water in.

No if they need bleeding they'll be cold at the top, warm at the bottom

If you have sludge you may need a power flush

Oh, damn.

So more likely to be sludge, then?

Deffo can't be air if it's cold on the bottom?

And what is a power flush?

Plumber sends chemicals around your heating system to break through the build up. £300 ish.

You can do the sludge removal yourself, though it is a bit of a faff.

IIRC you have to drain the whole radiator system, pour in some sludge cleaner liquid you buy in a B&Q-type place, leave overnight, drain and flush that through.

So you have to know where the tap-bit is at the lowest point of your radiator system and the bit the water enters from.

Or you could just get a plumber to do the power flush thingy.

(wow can't believe I actually did that once - clearly can't be that hard!)

Sounds like sludge. You can get a powerflush but it's expensive. To stop it happening again, you can install a magnetic filter (the sludge contains iron particles) and / or add a chemical to the water that changes the pH (stops the chemical reaction that makes the sludge). Good luck.

a friends house was always cold then they desludge the whole system and the difference was amazing they payed a plumber but they thought it was money well spent

Hello
I had a power flush today! Radiators now all working well and the house is warm again.
It was pricey, £625 for 14 radiators ( doubles count as two).
Hopefully the boiler will be more efficient so our bills will go down.

Thanks all
We will try to do it ourselves first and if it doesn't work, will get a plumber.

It makes such a difference, the heat is full on and yet the house is barely warm.

Yup sludge. Got mine done at the start of Sept and have definetly saved on heating since then. We rent though, so it didn't cost us.

One of the few things we did ourselves - is messy, but actually quite easy. (Mind you, one of our radiators never did entirely recover from being dropped down some concrete steps in the garden when being hosed out...)

Good luck and wear v.old clothes!