Re: Central heating boilers

[Simon Haslam <simon_haslam@xxxxxxxxxxx>]

I've got a Viessmann WB1B system boiler (there's a newer WB1C version
now) =
and have been v pleased with it - it has a long warranty (5 years or so)
an=
d hasn't missed a beat (3 winters so far, serviced annually). I had some
qu=
estions for their technical support and they were superb - same day
usually=
, even when referred back to Germany. They're still fairly unusual in the
U=
K I think - my plumbing firm sent one of their engineers on the Viessmann
t=
raining in Telford to get them certified (and for the extended warranty).
I=
did consider Keston as it would have been nice to use a British manufactur=
er and their specs looked OK, but sadly read nothing but trouble about
them=
online. Vaillant was on my short-list too - definitely more plumbers know =
them but they didn't have an OpenTherm interface (which was on my HA
wish-l=
ist, though as yet unused!). I think having something that your plumber
wil=
l be familiar/happy with is important - in that respect Worcester
Bosch is probably most common.

I've also got weather compensation, plus my HA system can switch in an
addi=
tional resistor (using a 1-wire controlled relay) to lower the flow temp
fu=
rther. If you compare the performance charts you will see a 10% or more
(II=
RC) difference in efficiency at something like 70C flow compared to 40C
(UF=
H) IIRC and so there are gains to be made. The benefit probably partly
depe=
nds on whether you can be bothered turning down/up the boiler output
betwee=
n autumn/spring and winter though. Weather compensation is built into the
V=
iessmann circuit board (this is their entry level too) but you need to buy
=
their thermistor/cable assembly, though it wasn't a ludicrous price
(~=A320=
I think) - providing you can get a cable to a north facing wall it seems p=
ointless to scrimp on it.=A0 I think with a better insulated house the
gain=
from weather compensation should be better than an old house too as you do=
n't need a high output to change the temperature, only to maintain
temperature in very cold weather. I can't remember if weather comp is in t=
he building regs for new build yet but I expect it will be soon.

Anyway, my new heating system made a huge saving on gas usage (~50%) but
th=
at was due to a lot of factors other than just the boiler (re-siting the
bo=
iler in the middle of the house & moving the pipes out of the loft,
having =
a small condensing boiler instead of a 10 year old F-rated oversized
(44kW!=
) clunker, proper controls (7 zones), etc, etc).

HTH



Simon

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