On Jul 25, 7:42 pm, Ed Sirett wrote:
On Wed, 25 Jul 2007 01:24:28 -0700, James wrote:
On Jul 25, 1:07 am, John Rumm wrote:
Ed Sirett wrote:
The continued use of the single pipe system is not ideal.
However with care about the balancing, thermostatic valve settings and
location of the thermostat it should be possible to make it work, albeit
with some control limitations.

Would you be able to meet the requirement for TRVs on each rad though?

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Ed, John,

Thanks for your comments, all very much appreciated!

When I replaced the radiators last year, I took the opportunity to put
TRV's on all apart from the two in the main living area (where I
intend to locate the thermostat when its installed). I balanced the
system as best I could and set the TRV's according to the use of each
room.

What I found was that even on the single pipe system all the radiators
worked well (really quite surprisingly well infact - given what I had
heard about single pipe configurations) and all the TRV's seemed to be
working just fine.

Whilst I fully understand its not ideal, the work required to put in
the second pipe is a major job to do properly, I have very old walls
and plaster which i'm really not keen to chase out in order to put in
new pipework (i'm not looking to create a bigger problem than I
already have!)

Ed, when you mention control limitations - what are you thinking ? are
you considering the inability to implement any zoning ?

Not so much that. Of course the single pipe run cannot be subdivided but
the TRVs will make it more controlled.

I was thinking that there may be issues with balancing the single pipe
against the two pipe stuff. It all depends on the layout.

You can think of the single pipe part as a large single big radiator
(which happens to have parts in several rooms). It has a larger
flow/return temp differential which is great with a condensing boiler.

Does the living room have any additional sources of heat? (fireplace or
large southerly facing window?) In which case it may not be the best place
for the over all heating thermostat.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is athttp://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQhttp://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQhttp://www.makewrite.demon.co.uk/BoilerChoice.html

Ed, Andrew,

Thanks again for the very useful information.

The living area has two radiators (neither of which have been fitted
with TRV's) and is quite a large open area. It has an open fireplace
which we use in the winter at one end.

I am planning on purchasing a wireless thermostat and timer (probably
the Honeywell CMT927) which has an optional table top stand to sit on
a bookcase or shelf. In this way, I can move the device around to find
the best location and then if necessary mount it permanently.

As a result of your advice, I have a much better understanding of the
single pipe system now and feel confident in bringing it up with
whoever I find to fit the boiler.

James