"Christian McArdle" wrote in message
. net...

The cheapest and more practical is what
is suggested: Alpha pump, by-pass,
flowswitch and TRVs all around. Then
split the system into two zones,

Obviously, the system would have been
overspecified, but it was an example
of the "best" rather than "best value".

Best, yes. Over engineered, probably yeas for an average home.

The system I'm just doing myself
will be converted to up and down
zones with a 2 port valve and programmable
controller each in the lounge and master
bedroom. The other rooms will have
to fend for themselves on TRVs.

I did this 10 years ago for a relative, except they had the downstairs stat
in the hall, which acted more as a high limit rather than a comfort control.
The upsairs is only on in tgemmornings and evenings, and if heat is wanted
outside these times, just flick the override switch. Now I would have two
simple timers for each zone, TVRs all around and an Alpha.

A system like that is pretty cheap,
easy to install (or even modify an
existing system to)

The pipework to split the system may be quite a task in some homes.

and allows separate timing for the
sleeping and living room areas as
a whole, which is quite an advantage
when the time usage profiles are so
different between the two.

The one I did saved about 20-30% in fuel. It was a big house, so made all
the difference. having two separate zones is a cheap undertaking, yet saves
more than fitting a condensing boiler.

The differences between 2
bedrooms, though, aren't quite
so great, so might not justify the provision
of additional zoning.

BTW, how does the Alpha know when
to restart? Does it "poll" at a certain
frequency to check the resistance?

It starts up occasionally to detect the pressure. On start up they can make
a stammering sound. This is normal as it judders by switching off and on to
dislodge any debris in the pipework.

A normal pump can be used except that a timer would have to be activated to
turn the pump when the flowswitch cuts out. A cheap one can got from RS,
Maplin, etc, and some thought into the operation and wiring. using an Alpha
and flowswitch is simple and easy.




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