Andy Hall wrote:
On Sun, 25 Jan 2004 18:40:38 -0000, "David Hearn"
wrote:
Andy Hall wrote:
On Sun, 25 Jan 2004 13:23:39 -0000, "David Hearn"
wrote:
Our hulk of a boiler (Baxi WM 531 RS) is nearing death. The heat
exchanger is leaking and we're finding we're getting a funny smell
now. Couple of months ago we had a different funny smell when I
split the thermostat's capillary tube but after replacement that is
still intact and the boiler is working, unlike before.
I believe the smell to be caused by the evaporation of the water in
the boiler and coming out the hole for the thermostat probe. Not
actually sure of the cause of the weird smell (X100 inhibitor,
Fernox Boiler Silencer or just some sludge) but its related to the
boiler being on, and the flames are burning nice and blue (though
flares up orange sometimes - I suspect when liquid drips into the
flame). When the boiler is turned off for an hour or so, there is
water sitting in the hole for the thermostat probe and rust is
getting worse around it.
Now, firstly, is this smell/gas likely to be dangerous? Obviously
you don't want to be drinking the inhibitor, but what about the
smell from it? We're making sure we ventilate the area well
(because its not a nice smell!).
This needs to be pensioned off pretty quickly........
Plans are underway for a few weeks time.
If its not dangerous, then I have a little more flexibility with
when I replace the boiler (few weeks, maybe month or so rather than
days). Longer is better as I can then fit around my Dad's
availability etc.
My plan is to go for a cheap/cheerful Ideal Classic SE RS boiler.
Current boiler is a 62,000 BTU (18.4kW) input with 44,500 BTU
(13kW) output. I assume that if replacing like for like then I
just go for one with a similar output (therefore the Ideal Classic
15kW version) rather than looking at the input rating.
As long as you are happy with the heating performance, then match
the outputs as you suggest.
Sedbuk's 'whole house' checker estimates about 10.7kW, so maybe I
could go for the 12kW version, though the 15kW one is closest to
what I've got, and that works well enough.
I wouldn't go lower than you have already.
My reasoning for this boiler is that I should be able to use the
same hole in the wall with the current balanced flue for the new
one (or with minimal work). Rather than having to brick it up and
put in a fanned flue (among other things).
It's really no big deal at all to put in a fanned flue. Most of
them are a set of concentric tubes and the size is smaller than for
unfanned units. I did the complete job from having removed the old
boiler to having the hole bricked up and the new flue located in a
couple of hours and I rarely lay bricks......
In our case the wall is rendered (with a Tyrolean finish?) and is
quite old. I would prefer to have as little rendering to do,
matching paint is another problem - and no plans on re-painting the
house!
In any case, there is no guarantee that the dimensions of a new unit
will put the flue in the same place as an older model, so at least
check that.
Yup - I'm aware of that, though I'm hoping that one balanced flue is
pretty similar in shape to another. Due to the size of our current
boiler (wide - width of flue and then another 6 inches) and the
shape of new boilers (narrow - about width of balaced flue) I expect
there'll be quite a bit of work inside to make good etc. Trouble I
have is that there's a hole in the ceiling for the plumbing and a
hole in the wall for the wiring - both within the casing area of our
current boiler, but outside of the casing area of the new one - so a
bit of work will be needed to make it look tidy - though we do have
some spare 50cm kitchen cupboards which may well allow us to hide it
away subject to manufacturer guidelines.
Also, I want one which I can install myself (with help from my Dad
who did his boiler a year or so ago) and doesn't require any
specialist gear to set up (ie. flue gas analyser). AFAIK, a simple
boiler like that should just require adjustment to make the pilot
flame a certain size and also to get the required pressure on the
test point.
I know the benefits of condensing boilers - and unless you can
install one without any serious test-gear, I wouldn't consider it.
On many of them you can. It isn't so much an issue of whether the
boiler is condensing or not but rather the age and origin of the
design. Some of the more sophisticated controls require the
use of a flue gas analyser to set up max and min gas rates.
However other boilers are set on burner pressure or on gas rate
measured by reading the meter and timing. You would need a
manometer anyway to do part of the soundness test and they are
about £15.
Don't suppose that you know of which boilers don't *require* flue gas
analysers?
In terms of installation, the only additional thing for a condensing
model is to provision the condensate drain and that is trivial.
Considering that you would save 20-25% of energy costs and some
quite inexpensive condensing models can be found, to me it seems a
no-brainer to use one, even accounting for all your other
expenditures and reduced income.
But I'll already be saving fuel costs by using a new boiler compared
to a 15/20 year old one - I wouldn't get 20-25% extra by going with
condensing over standard.
The Ideal Classic SE RS has a SEDBUK efficiency of 79.9% which is low
compared to 91% for the better condensing boilers. Some condensing
ones go as low as 85-86%. SEDBUK claim that large old heavy weight
boilers (which I would say the Baxi WM 531 RS we currently have is)
is only 55% efficient. Even if it was a lightweight one it would be
only 65%. Currently we pay about £30 a month for gas I think, £360
a year (which is between SEDBUK's heavy and light weight estimates
for a semi).
Assuming currently 65%, then if we went to 100% efficiency, we'd
spend £234 a year (£126 pa saving). 90% efficiency would cost £260
(£100 pa saving), 85% cost £275 (£85 pa saving) and 80% efficiency
£292 (£68 pa saving).
So, going with a condensing boiler I would save between £85 and £100
per yead and with the Ideal Classic I save just £68. The savings
over the Ideal Classic would be about £17 to £32 a year.
Ideal Classic SE 15kW £582 inc VAT.
Ideal Icos HE 15kW £675 inc VAT.
Are you sure that the vanilla SE is still available? I can only find
price references for the fan flue version and I believe you have to
add a flue kit for that.
Additional cost of condensing, £93. Best case it would take 3 years
to pay for itself, worst case 5 years. Might be worth a look
depending on cost, and how long we expect to live here.
Something I did fail to mention is that the system is currently
vented - and I don't want to convert it to a sealed system (work,
plus chance of leaks - at least 1 part weeps currently).
I was going to raise that point.
So - can anyone suggest (and recommend!) a condensing boiler that
meets the following requirements:
Suitable for vented/unsealed system (and not a system boiler).
Definitely does not require a flue gas analyser for
installation/comissioning - just pressure checks.
Does not cost more than £700 including VAT/delivery (any more is too
expensive/too long to recoup additional cost).
Reasonably easy installation.
Not quite at your budget, but it might be comparable once all the bits
are accounted for, would be the Keston Celsius 25. Discounted
Heating have this for £797 inc.
I considered this one for my installation the year before last so
researched it thoroughly. Ed Sirett and Andrew Gabriel have this
one and as far as I know are pleased. Tont Bryer fitted two in his
church.
This one does look nice, though I think its a little pricey (though good for
what it is) and the problem I would have with it is that its a twin flue
arrangement (minor point) but also that the expansion tank MUST be connected
to the return. Currently we have it connected to the flow - which fits in
with the Ideal Classic's requirement. Also the Celsius takes the pipes in
at the bottom - whereas we have the pipes coming down from the ceiling in
our case and would be a bit messy to route the pipes around (and don't want
the additional cost of the box which brings it 5cm out from the wal).
Nice boiler - though also very complex - number of PCBs etc. I must admit I
like the nice and simple design boilers where there's less to go wrong, and
less reliance on black boxes (ie. PCBs) - though I do speak as a Electronic
Engeering graduate.
Thanks
David