Hi

I've recently fitted a new 2m high stainless steel radiator . It has
8 vertical tubes which are connected at the top and bottom by a
horizontal tube. Although it looks great, i'm not that pleased with
its heat output, which is meant to be around 5,900 btus. I find that

a) the difference in the flow and return pipe is hardly noticeable.
These pipes are connected to either side of the lower horizontal tube,
and while this tube heats up very quickly, the rest of the radiator
heats up much more slowly. I have attempted to balance the radiator
with others in the house and i'm now at the point that other
radiators' LSVs are one quarter to one half turn from being closed
altogether. As i said, the lower tube heats up fine, but water
doesn't seem to mix with the rest of the radiator - it seems to just
flow straight out the other side.

b) the vertical pipe closest to the flow side takes much longer to
fully heat up than the rest - about an hour longer.

Is there anything i'm overlooking? Or do you think it's just the
design?

thanks

Stevie