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!).

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.

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).

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. I have to be able to
do myself as a number of large, unbudgeted costs have come along (like
replacing 2 rotten bay windows which are causing the bay to drop - approx
£4k) just as a baby is due and we go to one income. I'm not going to put
our family in any danger by doing it myself - but also we cannot afford to
pay someone £1.5k (minimum total cost for someone to supply/install it I've
had suggested) when we can just about afford £600 for the boiler.

So - what do people think about the Ideal Classic SE RS series boiler?
Reasonably reliable? Easy/straightforward to install? It'll just be a
simple replacement of a pumped (S plan I think) system running off an old
balanced flue boiler to another balanced flue boiler. Controls are up to
date - programmable room thermostat, 2 channel programmer, boiler stat, 2
zone valves, TRVs, pump etc.

One final question - what is the "standard flue pack" that is separate to
the boiler? Is this the balanced flue to go with it or is that something
different? I realise there is a Fanned Flue version - but we're not after
that - just the plain Balanced Flue.

Thanks,

David