On Thu, 01 Mar 2018 21:40:34 +0000, Vir Campestris wrote:

On 28/02/2018 23:46, Johnny B Good wrote:
A well planned out pipework run

Most of use inherit a system that was pre-installed, either by a
previous owner or a spec builder. They are normally planned for least
installation cost.


Hence my 'caveat' :-)

Mind you, when the installer has no choice but to use a rad distribution
manifold on each floor, placing the manifold blocks to minimise
installation costs usually works in favour of balancing the flows for
each radiator on their given floor. However, this still leaves some
variations in the balance of flows going from the main flow/return
manifolds serving each floor manifold.

In our case, on account of the DHW tank's location which dictated the
location of the pump and the 3 way mid position valve, this placed the
main manifold in the void between the ground floor ceiling space and the
1st floor which isn't too far from midway between the ground and 2nd
floor radiator circuits. I guess the LSVs were throttling the 1st floor
rads the most to balance the floor manifold flows. Mind you, with only
three rads on the 2nd floor and 5 rads each on the ground and 1st floors,
leaving the LSVs wide open on the ground and slightly more remote 2nd
floor rads would probably be about right once the 1st floor rad LSVs had
been adjusted.

Mind you having successfully removed the back bedroom rad last weekend
to allow the plasterer to re-plaster the room including sorting out the
crumbling plaster behind the rad, I'm encouraged to repeat the exercise
with the remaining 11 rads (the heated towel rail is a recent replacement
a mere 6 or 7 years ago) just to flush out the sludge which must have
settled to the bottom of each rad as I discovered with the one I had been
*forced* to remove.

I collected very clean water from that rad which only started showing a
hint of blackness when it was down to the dregs. Said water was recycled
back to the header tank after tying up the ballcock and bailing it out to
a dry state. The ballcock remains tied up for the time being until I
drain down my next rad for flushing out.

I plan on collecting the rad water for re-cycling back to the header
tank before refitting the back bedroom rad to minimise diluting with
fresh untreated mains water. I'm also planning on buying another five
litres of Fernox inhibitor[1] ready for when I re-fit the last two rads
so as to maximise the strength of inhibitor getting into the system and
minimise squandering inhibitor[2] on a header tankful of water to a
minimum.

[1] I lost about half of the 22 quid's worth I'd refreshed the system
with just 6 months prior to our 'Bull in a China Shop' builder hammering
a nail through a CH pipe running under the 1st floor bathroom we were
having revamped around 18 months ago. This 'accident' was despite my
warnings for him to take care to avoid damaging the pipework, the
presence of which I'd alerted him to.

His plumber repaired the pipe using some sort of speedfit/pushfit
coupling which, TBH, I'm not entirely sure can be regarded as a reliable
alternative to a good old fashioned soldered Yorkshire joint. Anyway,
I've been meaning to freshen up the now diluted inhibitor and now seems
to be an excellent opportunity to kill two birds with one stone (give
each rad its very first flush out in over thirty years and bring the
inhibitor back up to strength).

[1] I know it's considered a good idea to give the header tank a dose of
inhibitor to reduce bacterial growth notwithstanding that the anti-
oxidant component will be consumed in pretty short order but I plan to
hold back a quarter litre to add as a final measured dose rather than
just leave it to chance.

--
Johnny B Good