URGENT Radiators getting hot at the top but not the bottom

Jord199412 · Feb 22, 2021

Hello
I am having a problem with my heating system

My radiator are getting hot at the top but are cold at the bottom.

Was told by a powerflusher who came around and checked the radiators with a thermal imaging camera and was advised they are not blocked and does not need a power flush.

Decided because the system is 5 years old we have had a new boiler fitted and are still having the same problem.

Can any one please offer any advise on what to try next

Scott_D · Feb 22, 2021

The boiler, pipework and radiators are 5 years old?
Combi boiler or boiler and hot water cylinder?
Are the radiators pipes in 15mm pipe?

Post some pictures to give us some more info

Jord199412 · Feb 22, 2021

scott_d said:
The boiler, pipework and radiators are 5 years old?
Combi boiler or boiler and hot water cylinder?
Are the radiators pipes in 15mm pipe?

Post some pictures to give us some more info

It is a combi boiler, big system 22m bead with outlets to the rad at 15mm for 5 years every thing was fine that is why we fitted a new boiler today

Scott_D · Feb 22, 2021

If it’s a big system the boiler or pipework could be undersized.
What did the installer say?
Did they flush and balance the system?

Chuck · Feb 22, 2021

Jord199412 said:
Can any one please offer any advise on what to try next

There's not enough hot water is being pumped through the radiators. Could be several reasons for this so I'll just ask a couple of questions to get the ball rolling.

There should be an inline filter somewhere have you checked it doesn't need cleaning? Is the system controlled by a zone valve? If so does it seem to be opening fully? What setting is the pump on? How much gas is being used per hour by the boiler?