Rads heat-up at top only

[Appa]

Help !

I had a new boiler and radiators put in 15 months ago.

Thing is, the rads which are >1m wide all don't heat up at the bottom, only at the top and eventually get warmer at the bottom.

The installation company put a 15mm pipework for the 3 > 1m wide rads whilst the 3 other shorter rads have a 22mm feed to them all the way to the boiler.

The boiler is actually way over specced for what its doing so it's not the boiler.
I've managed to look at the boiler stats and its showing only a 4-5 degree drop between flow and return - any ideas ?

Many thanks

 

[Last Plumber]

Why is it way over spec?

Is that a mistake?

Oversized Boilers are or can be a major problem. A lot do it thinking they're being clever but you can over egg the pudding, so to speak.

If it is, you should speak with the installer/specifier

As far as your rads go, Are they heating the rooms?

If they too are way over spec then they won't need to get hot all the way through if they are fitted with TRV's

 

[Last Plumber]

Deleted double

 

[Appa]

Why is it way over spec?

Is that a mistake?

If it is your issue is with the installer.

As far as your rads go, Are they heating the rooms?

If they too are way over spec then they won't need to get hot all the way through if they are fitted with TRV's

No issues with over speccing - thats just for info.

Yes rooms heat up but obviously takes a lot longer.

As a plumber with the TRV's and valves connecting at the bottom of the rad, why would the bottom not heat up ?

 

[Last Plumber]

Sometimes slow circulation !

Cold water is heavier by volume than hot and so it sinks (Gravity) Hot water is forced up to replace it.

Sometimes the position of entry can make a difference.
e.g.
Some single rads will heat across the base before the top due to the water entering in line with the base, Doubles, tend to spread the water sideways on entry an that in itself can cause the rad to heat up one side and across the top first.

There are a few different reasons. A good Heating Engineer will be able to tell pretty quick if there is a problem and what might be the cause.

There are many variables with this subject !

 

[Appa]

Sometimes slow circulation !

Cold water is heavier by volume than hot and so it sinks (Gravity) Hot water is forced up to replace it.

Sometimes the position of entry can make a difference.
e.g.
Some single rads will heat across the base before the top due to the water entering in line with the base, Doubles, tend to spread the water sideways on entry an that in itself can cause the rad to heat up one side and across the top first.

There are a few different reasons. A good Heating Engineer will be able to tell pretty quick if there is a problem and what might be the cause.

There are many variables with this subject !

So the flow and return temperatures at the boiler are actually 2-3 degrees different - is there anything to conclude from that ?

Thanks.

 

[Last Plumber]

Not just from that no !

All that tells me is that there is little heat loss from the water circulating on that particular circuit.

There are lot's of reasons why that could be though. It's not guess work i'm afraid.

You need to get a Heating Engineer to check it over for you and tell you what's wrong with it.

 

[Last Plumber]

Not just from that no !

All that tells me is that there is little heat loss from the water circulating on that particular circuit.

There are lot's of reasons why that could be though. It's not guess work i'm afraid.

You need to get a Heating Engineer to check it over for you and tell you what's wrong with it.