"PeterC" wrote in message
...
I'm adding another radiator to a room; it'll be on the outside wall the
same as the present one. The gap will be only about 10cm or so, room to
get
valves in.
Instead of fitting valves to both rads., I was wondering about just
connecting them in series with a bit of pipe. Is there any major drawback
to this method?

If the radiators are largish, I would avoid putting 2 in series. The second
one would be cooler and less efficient. I also can't see how you could fit
thermastic valves which would work for both rooms.

If you were hell beint on fitting them both in series I would consider
fitting a top pipe as well. Then both rads would have similar top to bottom
temperature gradients.

You ought be able to get right angle lockshield valves within 10cm.