"F" wrote in message
...
(Snippage occurred ...)

As we have concrete floors downstairs, the pipes to radiators drop down
from the bedrooms. Unfortunately some of the drops do not have any way to
drain them off. I seem to remember mention on here of some kind of
alternative lockshield valve which might be useful in these
circumastances.
Anyone able to enlighten me?

Just had a major overhaul of the CH system and the plumber pointed out the
same problem to me - 2 rads on a drop from above with no drain cock. So, as
part of the overhaul included fitting TRVs and new lockshields, he fitted
one of the 'special' type. The valve is kind of like a tee where the 'leg'
attaches to the pipe, one end of the 'crossbar' attaches to the rad, and the
other end of the crossbar is the drain point. Apparently (not tried it, but
this is what he told me) shutting down the valve closes off both the leg and
tee connections at the same time. Then, with the valve closed, a bleed key
is inserted into the drain cock - up the spout, as it were - to remove an
internal plug, you attach your drain hose and open the valve again. Water
flows from the feed (or more likely return) pipe and from the radiator until
both are empty. Damned clever idea ... !

Oh, and by the way, to all those people who replied to my post a few weeks
ago on the topic of my sooty boiler, you have caused me to spend two grand
on getting a new boiler installed and overhauling the system. It was
unquestionably the right decision, thank you.

My CORGI pointed out that the vent for the air needed for combustion was
undersized - he showed me the data tables and there's no doubt he was
right - so bigger hole in wall and new vent fitted. When a replacement gas
meter was fitted a couple of years ago the replacement was smaller than the
old one so they left it sitting in mid air supported only by the gas pipes.
He was unhappy about that and re-made the outlet connection in a way to
permit the meter to be supported. Then on commissioning the new boiler he
discovered the gas pressure on the incoming main was insufficient so he had
to call Transco to come and fit a new regulator which they promptly did. He
was both amused and concerned that the "young lad" wouldn't agree that the
pressure had to be set with all appliances - hob, boiler and gas fire -
operating simultaneously, and had to make a call back to 'base' before he
was convinced and sheepishly agreed John (plumber) was correct! (Thinks, I
wonder how many other regulators he has fitted and set incorrectly ....).
The system is currently pumping a (second) bottle of X400 around in the
water and he's coming back next week to drain it down and re-fill with the
inhibitor added.

He left me the printout from his combustion analyser with the boiler's log
book and if I read it correctly, it seems to be producing 24 parts per
million of carbon monoxide which is apparently well within the required
limits, and is operating at a very respectable 87% efficiency. It's a
Potterton Kingfisher 60,000 Btu unit with a conventional flue. One thing
I'm not too sure about is the flow and return water temperatures, recorded
as 80 and 69 degrees respectively. ISTR 82 and 70-something being mentioned
here in previous threads as the numbers to aim for. Anyone care to comment?