On Mon, 26 Apr 2004 09:30:33 +0100, Andy Hall wrote:

On Mon, 26 Apr 2004 09:00:34 +0100, Mr E
wrote:

I'm planning on replacing the standard radiator valves with thermostaic
ones during the summer this year.

SNIP


Any advice appreciated.

Mr E

I have a very similar arrangement except in 8mm.

Since you have drain valves everywhere, that makes life easier in the
sense that you should be able to attach a hose and drain. However,
there are two kinds of drain valves - the better ones have an O-ring
around the spindle which is good at preventing escape of water along
it; then there are the cheap ones which don't and will piddle water
out.

So let's assume that the builders have been cheapskates and plan for
the worst. Heating water, because it contains iron compounds, will
stain indellibly.
What I do is to first of all cover the area in plastic sheet, run up
the wall. The disposable plastic sheets for decorating from DIY
stores are good. Then put newspaper down. Wrap pieces of old
towel around the pipes leading to the wall in case any water runs down
them. It stains walls too.
I then use cat litter trays from the supermarket under each end of the
radiator. Even with a drain cock, when you take off the valves there
will be some water left.

Hook up the hose and then you are away. Since you have drain cocks
everywhere, this is a great opportunity to flush the system at each
radiator position. You can do this each way by opening the valve at
each end of the radiator in turn so that water flows both ways. If
you have a sealed system, this is especially effective. Make a note
of how far each lockshield valve is open so that you can reset it.
Alternatively, you may prefer to just do the balancing procedure after
the plumbing is completed - it almost certainly won't have been done
properly when it was installed.

For the TRVs themselves, you can get 10mm versions, although they are
sometimes harder to get and more expensive. I used 15mm ones with a
reducing fitting. You can get small tail fittings which are 15mm at
one end - actually 15mm pipe that will go directly into the
compression fitting of the valve - and a 10mm female solder ring or
end feed at the other end. These look very neat when done.

I always buy Drayton/Invensys TRV4 valves. They last longer and are
better quality than the cheap ones. You can get a good price at a
plumber's merchants if you buy the lot in one go. Since it is a
PITA to change them, it's a false economy to buy the cheapo versions.

When you have finished, you can refill the system, venting the
downstairs radiators first. It's worth putting in some system
flushing product such as is made by Sentinel or Fernox and run it hot
for a few hours and flush again. You can check for leaks as well.
Then put in some corrosion inhibitor. There are gel ones that can be
injected into a radiator with a mastic gun. These are a little more
expensive than the liquid ones - I find it better to ignore the
instructions and to inject into an empty radiator before filling
rather than against the pressure of a full one. Alternatively, you
could plumb in a dosing point with a piece of 15mm pipe and service
valve arranged vertically somewhere convenient. This would allow
liquid chemicals to be used.


.andy

To email, substitute .nospam with .gl

Thanks for the reply. The stratagy you describe sounds like a good plan.
One further question about the TRV's.....I've looked around and found
Drayton valves, but they are so much more expensive, nearly 20GBP each. Is
ther not a cheaper TRV that anyone can recommend, I was hoping to pay
around half that price given that I'll need 13 valves altogether. Again
thanks for your advice.

Mr E