Radiator

[srb62]

Hi,
I have just had the old radiator removed and a replacement installed in a new position in the living room.
New radiator is not fully hot - the section near the bottom is not as hot as the rest.
The new radiator is a type 22 with a BTU of 6800. The old radiator was type 21 with BTU of about 5200. The pipes to/from the radiator are 8mm on a run of about 3.5m each way.
Someone has suggested to me that the problem could be the radiator is too powerful for the 8mm pipes.
Does this seem a likely cause and any suggestions for the best solution?
Thanks

 

[CountryFan]

Who replaced the radiator? Has it been balanced correctly?

 

[srb62]

Hi,
We paid a plumber to do the work. It hasn't been rebalanced.

 

[dilalio]

Turn other rads off and see what happens to new rad.

 

[srb62]

I forgot to say that we tried this - it did make the radiator hotter but the top was still noticeably hotter than the bottom.

 

[dilalio]

It always will be.

 

[srb62]

How do you mean? For what reason?

 

[dilalio]

How do you mean? For what reason?

Because heat rises.
It depends on the delta between top and bottom and how long it's been on for.

 

[srb62]

Two hours

 

[dilalio]

Why did you change the radiator?
Was the existing rad cold at bottom hot at top?
Are there others like it?
What boiler do you have?
Is the system sealed?
If so, what's the pressure been like?
Has boiler and system been attended to at any time?
How many rads?
All on Microbore?
Any that get really hot.
Rad temp and room temp not quite the same.

 

[numpty1]

Why did you change the radiator?
Was the existing rad cold at bottom hot at top?
Are there others like it?
What boiler do you have?
Is the system sealed?
If so, what's the pressure been like?
Has boiler and system been attended to at any time?
How many rads?
All on Microbore?
Any that get really hot.
Rad temp and room temp not quite the same.

you should know better,than to ask these questions after all its the plumbers fault the previous rad worked perfectly for the last 10yrs and was only changed because they wanted a different rad with a higher output in a different position.......

 

[dilalio]

you should know better,than to ask these questions after all its the plumbers fault the previous rad worked perfectly for the last 10yrs and was only changed because they wanted a different rad with a higher output in a different position.......

And you should know better that I like to put the cat amongst the pigeons sometimes!

 

[ericmark]

My radiators get hot and cold, as I have a non modulating boiler, but in mother's old house with a modulating boiler, the radiator would get hot when we turned up the heat for the room, but most of the time it just remained warm, which is how it should work, the TRV head regulates the water flow, so the radiator is just warm enough to maintain the room's temperature, if it is getting hot, then something is wrong. In the main, some wall thermostat is turning the boiler off/on rather than the TRV controlling the room temperature. Unless you're using an old boiler, which does not modulate.

 

[srb62]

Why did you change the radiator?
Was the existing rad cold at bottom hot at top?
Are there others like it?
What boiler do you have?
Is the system sealed?
If so, what's the pressure been like?
Has boiler and system been attended to at any time?
How many rads?
All on Microbore?
Any that get really hot.
Rad temp and room temp not quite the same.

Sorry, I think I've given you the wrong impression. I'm not actually the plumber just the guy who'd hired the plumber. Thanks for your help and apologies again.

 

[Harry Bloomfield]

I forgot to say that we tried this - it did make the radiator hotter but the top was still noticeably hotter than the bottom.

So are all mine, hot water rises, cooler water falls to the bottom. The nearer the room approaches the desired/set temperature, the more marked the difference in temperature, between the bottom and top.