Relative lives in an inner, three story town house and needs a new
boiler. The current ~20 year old boiler is located on the ground floor
with the flue running up through the other two (concrete) floors.
There's a garage to the front and a kitchen to the rear and the boiler
is in a walk-in cupboard between the two.
She's been told that the boiler must go on an outside wall with the flue
through the wall, or on the top floor with the flue through the flat
roof. Question is, why can't it go where the existing boiler is? Is
there a limit on the length of flues for modern boilers?
In article , F
It t' old days this was not a problem as a conventionally flued boiler
could draw air from the room in which it was sited and the exhaust gas
was so hot that it could easily find its way up a long large bore flue
to the top of house.
Nowadays it is not considered safe for new installations to draw air
from the room in the appliance is sited and the regulated requirement
for condensing boilers having low exhaust temperatures means that the
flue gasses no longer have the oomf to make it up a long flue on their
The solution is fan assisted balanced flues which are frequently
concentric (exhaust inside and inlet outside) and although extension
pieces are available they are expensive and there is a limit on the
length that the fan can suck and push the gasses.
Boilers do exist that are capable of driving long flues but this is a
specialist requirement so there aren't that many around and some of them
are expensive. Almost universally they split the flue into 2 pipes to
drive long distances. I know of:
Keston - Reasonably priced boilers, and flues are formed from low cost
(but inflexible) 50mm muPVC drainpipe. I have a Keston Celsius 25 boiler
but I'm not sure I would give it an unqualified recommendation
Mann Micromat - A top quality German boiler but pricey, extension flue
is flexible corrugated plastic tube which is cheaper than metal
extension but still expensive for long runs. Formerly distributed by Eco
Hometec but I've lost track of who are doing them now.
Ariston - Saw these in a block of flats a while back and noticed they
were using long flues via adaptors, no detailed info.
To cut a long story short, if you chose to go the long flue route then
you will be making life more difficult for yourself, you will be paying
more and tying yourself to a number of specialist suppliers whose
support network may not be as extensive as the mainstream market and as
a result you may have difficulty with spares in the future.
More mainstream boilers are most easily fitted to outside walls but many
can drive concentric flues of 3 or 4m which may mean that you can fit
them in a cupboard and route the flue to the outside.
See also the group boiler choice faq from Ed Sirett:
Thanks for that. The alternative horizontal flue through the wall into
the garage and then out above the garage door was one that I had thought
of but, for some unfathomable reason didn't go down too well with her.
In article ,
I ordered a set of servicing spares for mine a few weeks ago
thinking they might arrive by end of March when its service
is due, and unlike my previous experiences, every part was in
stock and arrived next day.
BTW, Keston stopped making the C25 over a year ago, although
I have seen stock still for sale quite recently.
Agreed, except for cost issues about the length of flue components etc.
Varies from maker to make but invariably they are all competing with each
other to make things as long and as versatile as possible.
One of the make requires a drain+trap at the base of vertical sections of
above a certain height.
In article , Ed Sirett
Andy had me worried there for a minute but it looks like they have
introduced the Qudos 28 as a mid level domestic replacement that fixes
some of the original issues I had with the Celsius 25. There are
separate control temperatures depending on the demand source with
thermistor sensor modulated control of DHW temp and they promise
compatibility with low grade heat from solar panels in the future. Full
list is: Room Compensation, Weather Compensation, Solar Control,
Modulating DHW Reheat, Solar Thermal, Analog Demand (0-10VDC), External
Lockout Signal, Remote Fascia Panel plus LCD control panel and display
of system params (flue temp, flow/return temp, other temp densors) in
installer mode. They've retained the 20m/50mm maximum flue length and
even extended it to 60m when increased to 65mm. Suffix H is heat only
without pump or expansion vessel, suffix S is a system unit with those
£722.08 and £788.13 inc vat for the 'H' & 'S' respectively at
I'm quietly impressed.
Using twin pipes (plastic drain around 2" pipe) 30 foot and more.
> Thanks for that. The alternative horizontal flue through the wall into the
> garage and then out above the garage door was one that I had thought of
> but, for some unfathomable reason didn't go down too well with her.
The Qudos 28 has a spiral tube stainless steel heat exchanger top mounted
burner design. They went back to their original designs. The Celsius by the
time they dropped it had all it problems ironed out. A late model Celsius
is good buy.
The Qudos is well priced for what it is.
She doesn't have a loft, just a top floor.
However, my neighbour has had a boiler installed in her loft. It went
AWOL after a few months, BG came out to fix it (the original fitter
couldn't get out to it and there were young children in a very cold
house) and the guy refused to go up into the loft. Elf and safety! He
was persuaded to change his mind when said neighbour asked him what his
supervisor would say when he smelled the alcohol on his breath!
In article ,
"Doctor Drivel" writes:
My biggest gripe -- lack of availability of spares in a timely
fashion -- looks like it might have got sorted too, but that's on
a sample of only one order. Might be as a result of Keston having
been bought out a while back.
I might consider them when a 17 year old Profile pops its cloggs
(although it's currently running faultlessly and has had no breakdowns
that I know of, certainly none in the last 7 years). When I looked about
6 months back, I don't recall them having a low powered non-combi in the
In article , Ed Sirett
The sophistication and the solar hook makes it attractive to the
specialist market and the techies here but I do wonder whether it will
make it in the mainstream market, it's just too clever. I hope that they
and it make it, at last a company who listen.
You don't have to use the clever bits.
It will work with just a simple switched live for the followers of Ned Ludd.
I doubt whether many people would use it domestically with more than a
thermostat and the weather compensator. The smart move would be to
include the sensor for that in the package because it's a very low cost
item (basically a two wire semiconductor in a weatherproof box).
It may be interesting for small commercial installations involving
multiple boilers controlled by an analogue or Opentherm controller.
Whether it makes it in the market will depend on the number of puffy
anoraks for Plumbcenter counter staff and lunches for their managers.
Matt, I fo fear that.
The ideal setup for this boiler (the Keston C36 combi is the same boiler
with a water section added) is to have the outside weather compensator
fitted (cost about £22). The DHW cylinder sensor (not sure of price) and
the Opentherm standard room temp controller/programmer/optimiser fitted
(Keston use the Honeywell Chronotherm, which can be bought a lot cheaper
elsewhere rather than the £133 Keston ask for it). Then this is a
substantial setup and at a price people can afford. Anyone can do that,
just as simple as rigging up crap stats.
The C38 combi can have the outside temp sensor fitted and the Chronotherm
optimiser programmer too. DHW is not an issue as it is a combi. Then for
what you get and pay this is also well priced. Keston have to offer
advanced control interfaces to five the boiler a hedge. Broag also sell a
well priced boiler offering similar specs using tried and tested parts too.
I have heard no bad reports on the Qudos range....yet. The Celsius turned
me away from Keston after making some super simple and reliable boilers
previously. It should be fine using parts from other boilers in the range.