I need a new 38kW condensing boiler with weather compensation) and have
singled out the Keston C40. (The Keston C25 is too small and doesn't
have weather compensation.)

Does anyone have any comments, good or bad, on the Keston C40?

Keston recommend using this boiler with a Honeywell "Chronotherm"
controller with Open Therm comms protocol. Again, i wondered if anyone
had any experience to share regarding the Chronotherm.

Lastly, Keston distribute a 300L Spa cylinder to go with the boiler.
Does anyone know who is the original manufacturer of the Spa?

Thanks, folks

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.

"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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Thanks, Martin.

On this newsgroup, Keston seems to have a mixed reception. Atag hardly
appears at all because it is so new to the UK

I've had a look at the Atag S-HR 35 which looks suitable. Do you have
any personal experience with Atag? Would you say that it has better
build quality than Keston?

I have just concentrated on the S-HR 24 so far as I don't install too
many high output units. The 35kw unit is exactly the same, but it has a
slightly elongated heat exchanger.

I don't think I can say a bad thing about the ATAG boilers. The units
are a slightly larger and they have a larger (80mm) twin flue system
than keston, but I have come to appreciate that a long small flue often
means noisier boiler. The ATAG units are very quiet especially as they
are running at low modulation for a lot of the time. They sell a
concentric flue, but having installed many keston c25's I now prefer
the twin flue options anyway. The twin flue system is plastic and
plumbs in easy.

You can tell a lot by looking inside a boiler and the blue angel is so
well constructed it is a shame to put the case on it. The control pcb
hinges out for easy access and layout of the boiler makes servicing
extremely easy. They have just started supplying an upgraded roomstat
(they call it a Brain!) which also provides a programming interface to
the boiler. I think they also have a solution for controlling the
boiler over the internet although I've not seen one of those units.

The blue angel boilers have a built-in 3 port valve which means
external control gear is reduced for most common installations. They
have an add-on package solution for controlling S and S+ systems. They
have a combi version in both blue angel and premier units, although if
you're in the combi market its unlikely you'd be budgeting for this
class of boiler.

ATAG boilers have been in the market for many years, although the
distribution has been limited. They are now playing catch up and
building up their customer base. I installed a Blue Angel boiler 1997
and the design has not changed since then.

I'd suggest you get some more information on the boilers and get some
references from people who have them installed. www.atagheating.co.uk
(seems under construction). Their number is 01243 673888 and if you
mention I gave you their name they might not be too surprised why they
suddenly get a rush of enquiries from uk.diyers ;-)

Martyn

On Thu, 24 Feb 2005 01:13:06 -0800, Martyn Pollard wrote:

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.

This is not my understanding of how the Keston (C40) works. It ignites at
about at a gas rate in excess of the minimum (say about 25% up the
modulation range). It then operates at this moderate rate for about 30s or
so 'testing the water' then ramps up to the required setting. It does not
IME just go to 'full whack'.

My other comments a

High powered boilers are unduly expensive presumably due to
lower production volumes.

The C40 is setup out of the box to work with 70C max flow temp for sub
zero outside temperatures. The consequence is that on milder days the
boiler will reduce the flow temp to the point where it has almost no
effect. This is adjustable but you need to be aware of it.



--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
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