Rad not getting hot at the bottom

[samba12]

Hi guys, i'm a central heating enginner and i'm having a bit of difficulty

A custermer has a 2 bed flat, with a worcester bosch 24i combi, their flat had 5 old rads, 4 k1 1.2m by 40cm (1 in each bedroom and 1 in the bathroom and the final one in the living room). they also have a 3m by 40cm k1 also in the living room.

They have very large windows double glaze in each room hence the rads can only be 40cm high.

They were complaining that the flat wasnt hot enough and the rads werent getting hot at the bottom, so were did a power flush which didnt help much, so we changed the k1's for new k2's (also offer to install one in the hall but owner didnt tkae us up on it), and that has made the flat quite a lot hotter.

But the large new k2 rad in the living room still is cold at the bottom, btw the valves are balanced

Any ideas why it could be? could the boiler be faulty? as the boiler should be able to handle 5 rads..

 

[seco services]

is it balanced properly ? relating to the rads cold at the bottom.

 

[samba12]

seco services was just editing to say they are balanced when you posted

 

[CharteredEngineer]

if you get too little flow through the radiator, then it will dissipate its heat so you will get cold rads at the bottom.

Either the radiator is too large or there is insufficient flow.

 

[Gasman28]

'They were complaining that the flat wasnt hot enough and the rads werent getting hot at the bottom, so were did a power flush which didnt help much, so we changed the k1's for new k2's (also offer to install one in the hall but owner didnt tkae us up on it), and that has made the flat quite a lot hotter.

But the large new k2 rad in the living room still is cold at the bottom, btw the valves are balanced '

Still sounds like a system fault. When you say powerflush, was it with a Kamco or similar machine?
Cold spots on rads normally equate to partial system blockages.

 

[samba12]

I cant remember the name of the power flush, probably kamco or something,

Since the new rad is getting hot at the top, makes me think that the pipes are feeding it fine

 

[tamz]

Since the new rad is getting hot at the top, makes me think that the pipes are feeding it fine

As a heating engineer you still have a lot to learn.

The answer is one of the above, all flow related.

Either the radiator is too large or there is insufficient flow

For the size of radiator.

is it balanced properly ?

or

Cold spots on rads normally equate to partial system blockages