"PCPaul" wrote in message
news
On Fri, 01 May 2009 01:39:27 +0100, Doctor Drivel wrote:

"PCPaul" wrote in message
m...
On Thu, 30 Apr 2009 17:45:43 +0000, YAPH wrote:

On Thu, 30 Apr 2009 12:36:00 +0100, Tim S wrote:

---8--- snip techie stuff ---8---

We'll be expecting a proper write-up Tim ;-)

Absolutely definitely.

It sounds very similar to what I'll be doing if/when I buy this place.
And I have an Arduino or two sat around looking for something useful to
do as well ;-)

Use a Remaha Broag "dual temperature"
boiler with integrated weather
compensation. The cheapest way of doing it.

I was hoping to use most of the existing stuff
(a decent set of evacuated tubes and a fairly
new 24kW condensing combi that can be
configured as a system boiler instead - but
can't take preheated input to use as a 'solar
combi').

Some combis have a low level pressure detector and will lock out. Most do
do not. If it does not you can use it on a vented system. A boiler
connected directly to a heat bank is far more efficient, than heating the
cylinder via coil. You will find that the makers use the same heat
exchangers on the vented and system boilers/combis. It will perform better
on a vented heat bank as there will always be full flow through the boilers
heat exchanger. The pump on combis are mainly on the return, so always
cooler water on the pump side. The pressure vessel in the combi is just
ignored. If it ever leaks just cap it off.

On Sun, 03 May 2009 10:09:54 +0100, Doctor Drivel wrote:

"PCPaul" wrote in message


I was hoping to use most of the existing stuff (a decent set of
evacuated tubes and a fairly new 24kW condensing combi that can be
configured as a system boiler instead - but can't take preheated input
to use as a 'solar combi').

Some combis have a low level pressure detector and will lock out. Most
do do not. If it does not you can use it on a vented system. A boiler
connected directly to a heat bank is far more efficient, than heating
the cylinder via coil.

I've got the installation guide for the boiler (a Vokera Linea 24). It
gives details for combi, S and Y plan installations by changing jumpers,
so I'm happy that it will drive it satisfactorily.

I checked with them about feeding the solar preheated water directly into
it (an posted about it ages ago) - they said the feed had to be below
28C. It doesn't seem worth replumbing the existing (wrong) solar
arrangement just to gain that much preheat.

(The only way I can see any logic in the current arrangement is that the
fitters expected to feed warm water into the output of a mixer and have
'Hot' and 'Cold' come out of the inputs...)

On Sat, 02 May 2009 21:43:50 +0100, Tim S wrote:

I suppose a GTO triac would be possible, but there's not much demand...

I knew about GTO thyristors but never heard of a triac version. And AIUI a
triac is not just 2 back-to-back thryristors since it can be triggered by
pulses of the same polarity for each half cycle (isn't it? I could be
wrong)



--
John Stumbles -- http://yaph.co.uk

There's nowt as queer as folk.
Especially other folk.