"N. Thornton" wrote in message
om...
I like the look of this one. Well done to IMM. Assorted quotes.
.. and probably quite quickly since the first
heat exchanger will have very cold mains
water and have quite a transfer rate. A typical
domestic system will have 60-100 litres in
the primary circuit so there is a reasonable
amount of stored energy but at the likely
temperature, less than a thermal store.
Interesting nonetheless.
But that isnt a problem in itself. When you're
filling a bath it makes little difference if the
first half of the fill is faster or hotter
than the second, its the total fill that matters.
Extracting the CH heat will improve fill speed
relative to simple boiler output alone.
Most people,bath in winter
rather than summer, so perfect.
I find this an odd comment though 
But true.
In summer, taking just 10C of heat from the
rads is going to reduce summer HW heating
costs a little: the heating temp rise will be about
20-65 = 45C instead of 10-65 = 55C. Thats in
the region of 20% reduction, and thus also
20% more heat / flow at the tap than you
would get by just running the cold mains through
the boiler.
Now onto the conservatory bit:
It could be honed to be more efficient,
here and there. One way is to have
the cold water mains that supplies the
DHW laid under a concrete floor of a
southish facing conservatory in 22mm pipe.
This also acts as a pre-heat. So,
1st stage pre-heat, the conservatory.
2nd stage the heat stored in the
system, the third the boiler. It is extracting
heat from around the building to do
something useful, rather than waste space
with stored water cylinders.
While this could be done, it is a particularly
inefficient way of doing solar heating, and
would have no real hope of paying for its
installation cost.
I have done it. See the clip below froma previous post.
The heat gained from the conservatory
is free via solar gain.
not at all, it would be especially expensive.
Piping and plumbing is not free.
The solar gain is free. It is cheap enough to do on a conservatory
installation. A retro would be more expensive. See clip below.
There are other ways to improve the
heat delivery to the bath and cut
energy use as well. Another heat
exchanger under the bath, operating
between the cold bath tap /shower and
the bath waste pipe will recycle
much of the heat that goes down the
drain during showers, and will
thus enable a HW system of limited capacity
to deliver much more performance, since
the HW is mixing with a warmer cold supply.
And it looks like thats just whats needed on
this system. And from what I've
seen the payback looks good for these.
Do a Google on subject "Designing DHW... Fuel costs - electric is cheaper !"
This is covered. A dedicated unit is available. Having the drain water
heat recovery unit on the shower is the most cost effective.
So, doing what I suggested above: by having a conservatory floor pre-heat
cold mains water, recover heat from a shower drain, use the heating system
as a thermal store and the power of a largish boiler great economies can be
had and decent flow rates.
Regarding UFH in a conservatory. A neighbour recently had a conservatory
fitted. I suggested UFH in this, as the back wall of the conservatory was
the garage. I also recommended insulating the garage wall on the inside
with Cellotex too, to reduce heat loss of the conservatory in cold weather.
This he did. He has a combi boiler delivering 13 litres/min. I also
suggested installing alongside the UFH pipes 22mm plastic pipes too. In
fact far more of it than the UFH, as much as could be installed in a large
loop. This 22mm UFH pipe was to take in the cold water mains that supplies
the combi. He fitted it all in 28mm to get more water volume under the
floor. The advantage was that in winter the UFH would heat the floor and
the cold water mains would gain heat from the floor, pre-heating the combi
water giving a higher flowrate. In summer, the sun playing inside the
conservatory would pre-heat the 22mm mains pipe under the floor. Also the
cold water entering would cool the floor cooling the conservatory.
The total volume of mains water in the pipes under the floor is about 30
litres. The conservatory came on line in August and immediately the rise in
mains water temp was apparent just by the sun playing on the floor. The
floor was notably cool, especially in periods when water was being drawn
off. Also water absorbs 3-4 times more heat than masonry.
Now it is in winter the mains water is pre-heating by the UFH to well over
25C. Not bad. He fills his baths far faster, not to mention the savings on
DHW bills too. Also the sun plays inside the conservatory, even when 3C
outside and heats it up, heating the floor too, which in turn pre-heats the
water supplying the combi. Very simple and very effective so far, and
nothing to run and never goes wrong.