On Thu, 06 Nov 2003 11:50:40 +0000, David Hearn wrote:


"Ed Sirett" wrote in message
news
On Wed, 05 Nov 2003 14:18:50 +0000, Andy Hall wrote:

On Wed, 5 Nov 2003 12:51:53 -0000, "David Hearn"
wrote:

I'm just thinking about the cost etc of replacing our old wall hung Baxi
boiler. No urgent requirement for it to be replace, and therefore no
real
plan - mainly just thinking about the sort of cost we may have to expect
should we need to do this sometime.

Currently we have a balanced flue (boiler on external wall in kitchen)
with
feed/return and gas pipe coming down through the ceiling above (its a 3
bed
1930's semi).

What are the pros/cons of condensing boilers? Smelly flue gasses and
mist,
along with higher efficiency.

Well I think we've done that one to death in numerous posts. They
certainly can make the cost savings suggested on the SEDBUK site. I
am saving something between 25 and 30% of gas consumption, and have
actually added about 10% of heat output to warm my workshop for part
of the day.

Some types with premix burners (where the gas and air is mixed before
the burner) do release a little unburnt gas when igniting, but this is
seldom noticable. From the chemical perspective, the emissions of
NOx gases are way down on older boilers. Other than that the output
is water vapour. Depending on the boiler and operating conditions, a
condensing boiler will give a plume of water vapour at the outlet.
However, since they modulate down in output, most of the time this is
not substantial and with a well designed product, most of the water
vapour doesn't leave the boiler though the flue but is collected by
the drain.

At the present time there is a minimum SEDBUK efficiency of 78% as a
requirement for new boilers as part L1 of the Building Regulations.

There is a proposal (which you can find on the ODPM web site), to
raise this limit to 86% from April 2005.
This will effectively take all non-condensing boilers off the market
unless there is some technology miracle, because the highest is
currently 82%, whereas condensing technology achieves 90%+.



This means that I'm going to have to find a favourite condensing combi.
I feel content with the Vaillant Ecomax products but they are seriously
expensive at over £1k trade price.
I guess the Ideal ICOS might be OK. Could try out the Glow Worm cxi range.

What about the Vaillant THERMOcompact? Am I right in saying that this is
their non-combi boiler? Seems its priced between £460 inc VAT (but
excluding flue and timer) for 615E and £721 for 628E. Am I right in saying
that Vaillant is a good make then?

I think you mean the Turbomax+ range - this is the stock in trade for me [1]
These boilers are some of the best of the non-condensing units available
but these will not comply with the eventual requirements which effectively
means that only the condensing units will be permitted. [2]


What would I expect for a fitter to supply and fit a boiler I could buy for
£720 myself? Okay, they get to pocket the discount or whatever, but what
should I be expecting to get it supplied and fitted? £1k total, £1.5k?
Realistically, there shouldn't be much work to replacing a boiler should
there? From what I read about the Vaillant, it said "Installing a
THERMOcompact means a real saving all round. Typically, the additional
components required to fit a conventional boiler can add over £50, with
extra installation time of around 1.5 hours." AFAIK, its just disconnect
the old boiler, put up new boiler. Wire in, plumb in and test. Of course,
that's a very simple look at it, but there shouldn't be any/much more
plumbing necessary. If there was, (like removing header tank or something)
then I could do that before hand.

Thanks for all the help - its been really helpful.


The plumbing aspect is actualy a very small part of installing a new
boiler. As often as not the combi is replacing a conventional system there
are cylinders to remove and new connections to make. (Ideally you want to
change the gravity CW to mains to balance any mixer taps and often as not
you'll need to change the WC cistern valve - also you might have a leak
on the old plumbing when subject to mains).
7
A considerable amount of work can be involved in making good the old
balanced flue hole ( OK less up-market installers will leave the metal
work in place and just bung some foam in it).

A considerable job is the flushing out of the old system especially if it
died due to corrosion. The there is the upgrading of the gas main to
support 26kW input or more. The flushing again with chemicals and adding
inhibitor.

Don't forget the filling in of the Benchmark log book - if that's done
properly with measurement of temperatures, flow rates and gas rates it
takes a fair while.

Then there is the likely hood that the old system had problems:
Some places too hot, others too cold, other rooms needing TRVs to comply
with building regs. Needless to say the new system will need to be
balanced (the old one may have been really unbalanced), that takes time
even with a IR thermometer.

I charge around about 1000 labour to fit a new boiler give or take.
A good 4 days work if done properly. Combi to combi can still take
2.5 days.

[1] Well nearly - I'm tempted to keep a 824e in my store all the while
just so I can respond more quickly to emergencies.
[2] I know there are ways to be able to fit a low efficiency boiler but
I expect they are too difficult to calculate easily whilst estimating a
quote.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html