On Fri, 17 Jun 2005 14:25:01 GMT, Martin Evans
wrote:
I've had a British Gas man around today to quote for a new condensing
boiler. My existing set up is:
o boiler - very old - over 25 years, wall mounted. Flue straight out
back to outside above head height (about 5-6ft to next doors house).
o gavity fed hot water with thermostat on tank, controlling valve
(motor currently broken so manually fixed open although I have a new
motor for it) and boiler
o water tank in loft feeding central heating
o one room thermostat in hall
o most (not all) radiators with TRVs - radiator in hall where room
thermostat is located does have a TRV.
o newish (3 years) programmable controller with separate CH and HW
settings and 1 hour, overrides.
o relatively new (3 years) myson cp53 pump.
During the conversation he told me:
1. it is against the law to not fit condensing boilers now.
From other postings this would seem true.
Generally this is the case. There is a system for exceptions based on
location and work involved to site a condensing boiler which applies
points to a number of difficulty issues. However, if it is a
replacement for an existing wall mount boiler then you are unlikely to
meet the exclusion criteria.
2. They would remove the room thermostat as it was bad to have it in a
room where radiators have TRVs.
Other posts to this group seem to suggest having a room thermo is OK
but not to have TRVs in the same room.
There has to be a means of locking out the boiler when the heating for
the house is satisfied and this normally does mean a room thermostat.
It should not be in a room containing radiators with TRVs because the
two will tend to fight. The correct solution is to remove the TRVs
not the room thermostat, although the latter could probably usefully
be changed to an electronic optimising type.
3. When I said I wasn't sure if we had a bypass and if we went all
TRVs I thought we'd need one he said all their condensing boilers come
with a built in bypass.
Many do, and possibly all the ones that they sell, but I am not sure
that this is universally the case. The manufacturer installation
instructions will specify whether a bypass is needed or not.
4. Regarding placement on the boiler he said manufacturer specs said
their must be at least 600mm space in front of the boiler although it
was OK in a cupboard so long as with the doors open their was 600mm in
front. As a result he suggested installing it around the corner from
where it is now.
The manufacturer's installation instructions are the definitive source
of space requirements.
5. Our gas meter was not earthed and so they would have to earth it
all. I'm not this is true since I remember a large earthing strap
behind the gas meter where the pipes come into the house - I cannot
investigate this now.
There should be electrical bonding from the meter to the main earthing
point in the house. The gas supply should not be used as the
electrical earth.
6. condensate from new boiler was not a problem since the boiler will
be sited next to a soil pipe.
Correct. It needs some from of suitable entry into it, though.
7. our system was wrong be cause there is not at least 1.5m between
the top of the boiler and where the pipes go into the cylinder. This
would cause our boiler to switch on and off alot when only heating hot
water.
If the existing system is using "gravity" circulation to heat the HW
cylinder then the vertical vs. horizontal pipe runs can matter.
However, modern boilers, expecially in a new system like this are used
fully pumped so it doesn't matter.
8. conversion from gravity fed to fully pumped was a time consuming
process. Some sort of air valve would have to be installed - I'm not
sure exactly about this. The system would have to be fully pumped
which mean installation ot 2 new valves and pump.
Waffle. It might be worth installing a new fast recovery cylinder to
make the most of the pumped arrangement.
9. It was around 3 days work.
Could be.
10. the quote left has a "the effects of pluming have been explained"
but they never were.
You may get a plume of water vapour from the boiler flue under certain
conditions. These are typically most noticable when the boiler runs
flat out on a cold day. If the flue is facing the neighbour's
boundary and is close to it, then this may be an issue. However there
are flue types for some boilers that can be routed over several metres
and can exit in a completely different place. Some can even be 50mm
high temperature waste pipe. Of course BG might not have these on
their list.
11. He criticised the current electrical installation a lot. Wrong
cable used throughout - should all be flex - and told me a horror
story about a house fire near us caused by wrong electrical
installation where the insurers were not fully paying out after
identifying sub standard electrical fitment of halogen lighting.
Possibly. Certain cables should be flexible types. However, the way
it's described sounds more like FUD to justify higher quote.
12. When I asked how he would calculate what size of boiler we'd need
he said he didn't need to as it would be a modulating condensing
boiler which constantly monitors the exit and return water temperature
and adjusts automatically. I did not think this was a satisfactory
answer since clearly if he fitted a 1KW boiler it would not sufficient
(absurd example I know).
To an extent that's true. If the current boiler is adequately heating
the house, then fitting one having somewhat more capacity is fine.
They do modulate their output over a wide range.
Needless to say I was less than impressed but then came the:
Total quote was for £3498 including VAT (and £100 trade in discount)
with some significant numbers being (not including VAT):
British/Scottish Gas 330 HE Condensing Boilrer (inc labour and
installation) £1559
specialist building work (3) £174
can't imagine what this was other than repositioning flue
connect boiler electrics and test £64
glow-worm Xi std horizontal flue (800mm) £154
glow-worm Xi flue extension (500mm) £28
glow-worm Xi 90 flue elbow £31
radiator valves (15mm angled W/H & L/S) £26
Now he has left I don't understand this as we never spoke about
adding radiators or valves.
controls pack (2*22mm 2Port) Prog. (UP1) £307
convert to fully pumped 22mm (5mtr head) £312
powerlush - £195
install ME bonding £112
exectrical and mechanical supp bonding £79
there was other stuff like waster disposal, pipe insulation, fit pipe
insulation etc.
I was somewhat surprised by the size of the quote and the cost of the
boiler - seemed pricey to me.
Any useful comments?
It is a high quote for this. It doesn't really matter how they've
carved it up, the overall price is what is important.
I would have thought that £2000 was nearer to a reasonable target for
a good boiler and the works described - more if you change the
cylinder, and I would suggest that, because the water will re-heat
faster and the boiler can return to heating the house sooner. With
most control arrangements, the HW has priority over the CH, so you
really want to heat the water quickly (it is more efficient if you can
transfer a lot of heat quickly) and then return to CH.
--
..andy
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