On 26 Nov 2004 10:56:33 -0800, (Mary Hinge)
wrote:

Phil Addison wrote in message . ..

This 1 inch pipework sounds like a "single-pipe" system. This is an old
and discredited system for domestic properties and the balancing FAQ
process will not work with it. Is there a single 1" pipe passing under
each radiator, with both the flow and return of the rad connected to it?
Do you have calipers to check the diameter, because the old pipes were
1" *internal* diameter whereas modern ones are 22mm *outside* diameter?
I don't have the o/d of imperial pipes handy, but you could have 3/4"
i/d which has an o/d close to modern 22mm pipe.

If I am right about this, it could be that the pump is inadequate for
the new zone that you have, which presumably uses two separate 15mm flow
and return pipes. Can you see a make/model label on the pump?

Definately not a single-pipe system. The 28mm feeds the main CH zone
(upstairs and downstairs rads) with separate flow and return, I
suspect it probably drops down to 22mm somewhere under the ground
floor after the 22mm flow and return for the upstairs rads splits off.

The pump is a brand new Grundfos Alpha 15-60 and yes as stated the
conservatory zone is all 15mm. You might need to re-read my original
post for more background.

Oops, yes forgot that - I remembered the Edwardian bit and mention of
some things being old. So basically, its back to what i said befo You
need to balance it properly before we can do anymore diagnoses. With the
info to date it appears to be an out of balance system, which is common
for a new installation - most plumbers just do not understand balancing
and either don't attempt it or don't achieve it.

You haven't yet said the make/model of the boiler, but assuming it is a
modulating one, at 30kW rating it may not modulate down to 3.4kW so you
may have to expect it to cycling on off to a degree.

Summarising the balance process, you put the pump on max, open all the
rad valves (LSVs, TRVs, or hand valves) and allow it to heat up.
Normally at least one rad will have a cooler return. Ignore those, and
go to the ones with very hot returns and start shutting down their LSVs.
That will send a greater flow to the cool ones which will show an
increased return temperature. Keep repeating this procedure until all
returns are very hot. Ideally use an IR thermometer to evaluate the
actual return temperature - it makes it easier. Don't try to get a
specific temperature drop, just get them all about the same.

If you can achieve that, then you can think about adjusting the pump.

Phil
The uk.d-i-y FAQ is at http://www.diyfaq.org.uk/
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