Radiators warm at top, cooler at bottom. No air locks.

JustAnotherSaver

I've had a feel & many of the rads at our home are warmer at the top than bottom. We're not talking top being 100c, bottom being -250c, but there's a difference for sure.

I tried for air locks but there's none.

We got the house Nov 2013.
Rad system was fully drained Feb 2014 & re-pressured (had a leak caused by me)

I noticed if you blast the rads up at #5 on the TRV then the difference is minimal, if at all (in other words, bloody hot!), but it's when it's at #3-#4 which is what i have them at.

Just wondering what the likely cause is & more to the point, how do you get the same temp throughout the rad?

Seronera

Its called physics.Hot water is less dense than cold water, so the hot water in a radiator rises to the top. Guess where the colder water goes.

Of course older radiators may be full of sludge at the bottom, but yours don't sound as if they are. As long as a rad is hot at the top, its normally doing it's thing as best it can.

Kiran

My first thought was sludge. If you take the rad off and flush it with a garden hose give it a bang at the bottom and see if you get black sludge coming out. If there is you need to clean it properly as after you've dislodged it its going get back into the system

Seronera

OK, to see if it is sludge test as follows. Turn heating on pretty high (23c-25c) or more for one hour with radiators full on. Then put your hand...(carefully as it could be very hot) on the middle of the radiator half way down and towards the base of the radiator. If that bit has got reasonably hot then its not sludge. All rads will have some deposits but the point at which you flush them out is when significant parts of the radiator just stay cold at the bottom after extended running.

If you are still determined to flush it...leave it until the warmer weather or you will make yourself very unpopular. Remember there will ALWAYS be a temperature gradient on a radiator with the top being hottest and the bottom coolest as the water circulates internally. Don't get too hung up on it..as Scotty said on the Starship Enterprise "Ye cannae change the laws o'physics".

saveallmymoney

JustAnotherSaver wrote: »

I noticed if you blast the rads up at #5 on the TRV then the difference is minimal, if at all (in other words, bloody hot!), but it's when it's at #3-#4 which is what i have them at.

Just wondering what the likely cause is & more to the point, how do you get the same temp throughout the rad?

Sounds entirely normal to me.

ariba10

TRV stands for thermostatic radiator valve.

It responds to the room temperature.

If the room temp is higher than what the valve is asking for it will shut off itself.

It is not like a common stop valve.

It will open and close internally without any outside indication.

jayyar66

I agree, sounds like the radiator & TRV are working just as they should, don't worry. HTH :-)

JJ_Egan

Useful CH radiator info here .

http://www.shadlock.co.uk/energy/heat/chbal.htm