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Smile Sealed CH Radiator problem

Hello !

I have a sealed (ie pressurised) gas central system. Majority of radiators are fed through 8mm “micro-pore” copper pipes which are orginal to the house build of 1992.

The boiler is 1 year old and running at 1.5 BAR and really kicks out some heat

I have read the FAQ wrt radiator balancing and understand the concept.

A couple of the radiators do not get as hot as others despite having balanced the system. So if I feel the 8mm pipe (to what I think is) feeding the radiator it is too hot to touch for too long but the return valve pipe at the opposite end is considerably cooler. I have opened both the return and flow valves to their maximum flow but this temp differential still remains and the radiator does get hot but not as hot as some others.

Any help would be much appreciated. The only thing that spring to mind is that perhaps the return valve is stuck in one position despite rotating (doubtful) – or the radiator is bunged up with sludge ?

One other quick question – surely when trying to determine which is the inlet and return end of a radiator - if one of the radiator feed pipes is very much hotter than the other this would indicate that it is the inflow. The reason I ask is that all the downstairs rads have an integrated bleed valve on one side (which I took as being the return side). But I have found that this side produces consistently hotter feed pipes which to my small brain indicates that they are the inflow

Hope this makes sense

Many thanks

Tim
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Set Square
 
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In an earlier contribution to this discussion,
Tim Kedwards wrote:

Hello !

Majority of radiators are fed through 8mm "micro-pore" copper pipes


Blimey, I hope not!! Micro-BORE more like. (You don't really want them to
*breathe*, do you?!)


A couple of the radiators do not get as hot as others despite having
balanced the system. So if I feel the 8mm pipe (to what I think is)
feeding the radiator it is too hot to touch for too long but the
return valve pipe at the opposite end is considerably cooler. I have
opened both the return and flow valves to their maximum flow but this
temp differential still remains and the radiator does get hot but not
as hot as some others.

What sized radiators (in terms of their rated heat output) are they? Does
each radiator have an individual 8mm feed and return pipe, connected back
into something bigger - or is a single 8mm feed shared by more than one rad?
[There's a finite limit to how much heat you can reasonably carry through
8mm pipe. I forget exactly what it is, but it's in the region of 1.5 - 2 kW]

What happens if you turn all the other rads off - do the 2 cool ones get hot
then? If so, you still have a balancing problem. Is your pump running on its
maximum setting? If not, turn it up a notch and rebalance. It it's already
at max, or if these rads are too big for 8mm pipe anyway, you may need to
increase the pipe size.


One other quick question - surely when trying to determine which is
the inlet and return end of a radiator - if one of the radiator feed
pipes is very much hotter than the other this would indicate that it
is the inflow. The reason I ask is that all the downstairs rads have
an integrated bleed valve on one side (which I took as being the
return side). But I have found that this side produces consistently
hotter feed pipes which to my small brain indicates that they are the
inflow

It doesn't matter which side the bleed valve is. Integrated ones are often
on the right - but which side is feed and which is return is usually
determined by which is more convenient from a plumbing point of view. The
bleed valve simply lets air at at the highest point, regardless of water
flow direction. Your assumption is right about the feed pipe being hotter
than the return pipe.
--
Cheers,
Set Square
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