"Martyn Pollard" wrote in message
oups.com...
Other boilers with built-in weather compensation are; ATAG Blue Angel
(shr-24), ATAG Premier and Viessmann Vitodens 100/200. Build quality
from these two manufacturers is excellent and are well worth a look if
you are still keeping your options open. Cost is going to be similar to
C40.

The ATAG works slightly differently to most boilers(esp kestons) in
that it 'modulates up' rather than power on at full whack then try to
slam the brakes on to match the load.
With the weather comp brain unit it will run most of the day at a low
output (condensing) rather than a few hours at high rate. It also has a
stainless heat exchanger which looks more like an engine block than the
usual squashed circular design. I personally think this arrangement
gives optimum operation when working at low outputs (3.9kw with the
24kw model). You get a 10 year warranty on the HE if its installed by
approved engineer.

Viessmann use squashed circular design heat exchanger. If you go to
their uk website you can request technical information and look up your
local installer. You can buy viessmann through plumbcenter/PTS but I
would suggest you find an installer who is familiar the boilers first.

There is also http://www.eco-homtec.co.uk, who also do integrated
compensators.

The Mikrofill Ethos 46 is in there too.
http://www.mikrofill.co.uk/products/ethos36.html

ATAG do modulate quite low which is a big advantage in some cases. They are
new to the UK and service and parts may be a problem. Viessmann have been
in the UK for a qhile now and only just got their act together.

If you want a solid simple high output condensing design then get an Archie
Kidd boiler (the first in the UK in the early 1980s), and install an
external weather compensator. One can be bought for £160. It will not
modulate the burner as the integared boioer units do.

http://www.hwch.co.uk/kidd.html

Best use a thermal store and have a weather compensator heat the store to
what it dictates. Then a simpler, and cheaper, and potentially more
reliable, boiler can be fitted that only heats the stored water mass. Then
boiler cycling is eliminated. Also two cheaper, simpler boilers can be
bought and coupled to the store which gives redundancy. I would tend to
lean to this approach.




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