A huge thanks to all who replied to my post - many of the comments
have been useful in helping me understand some of the issues I had
with the visit by BG to look at upgrading my heating system.

This is a long post including an attempt at a summary of what I think
I've learnt. Hope it is useful to others as a illustration of my
confusions and the problems.

Since BG came to see me my wife found a local plumber and I had also
rung a local plumbing comany for a quote. I'm a little nearer a
decision but I think the old advice of always get 3 quotes has a big
draw back - you get a different story from each one. Not being an
expert in heating systems when I'm confronted with differing advice it
just lowers your confidence in any of it.

The differences in quotes and advice is vast including (if any are
reading I hope my summaries are accurate but if not I either
misunderstood or you did not explain it well enough):

o BG suggested keeping my existing system with what seems like a
rebadged Glow-worm 30Hxi (thanks Tony). Their quote as BigWallop
suggested includes effectively insurance on the new system components
and the rest of the remaining system for 3 years (or so I was led to
believe - no documentation on that). My shower pump stays so I keep a
good output from my shower but still have to put up with the noise
from it. Cost £3498 including VAT.

He did not mention possibility of a sealed system or combi boilers.

BG never left my old kitchen where my existing boiler is located, and
didn't ask to look at my water cylinder. He did have a laptop,
firewire printer and could print out a full quote including colour
marketing on the rebadged boiler though.

o plumber 2 (who spent a considerable amount of time with me - what
patience) suggested going to a combi boiler (although he would fit a
conventional one) - in fact a Worcester Greenstar 440 floor standing
combi boiler. He said

a) at 20l/min at 35 degrees C rise, running on mains pressure (subject
to testing mains pressure which I'm given to believe is good) it was
more than sufficient to match my existing pumped shower and everything
else.

b) it would be cheaper to install than keeping my existing system as
it was far less components and mostly required ripping (bypassing)
existing system out rather than renewing/replacing. Basically, the
cold water tank would be bypassed, the cylinder goes, my shower pump
goes, electrics are trivial since all that is needed it something to
the boiler. I liked the sound of losing my shower pump IF the output
at the shower head was as good since the shower pump is noisy.

c) my gas supply to boiler was 15mm and needed to be 22mm. There is no
easy way to get a 22mm pipe from the 22mm pipe at the back of my meter
to the boiler but it could be run outside (around a 3m run) so long as
the pipe was held off the wall.

d) To check the new system would cope/match my existing shower pump I
needed to lookup the output from my pump (i've struggles with this as
the plate on it quote 3 l/min numbers). Also, I needed to check the
spec of the shower valve in my ensuite to ensure it was OK for the new
increased standing pressure.

e) we discussed pluming etc and the flue would be routed outside and
up the wall to above head height.

f) we discussed reliability of Worcester 440 and he said he had fitted
loads, it was good, needed to be serviced once a year and although
slightly more involved than a conventional boiler was not time
consuming or expensive. On board diagnostics would even detect a leak
in my heating system.

g) Mentioning some pipework in concrete floor he was unperturbed,
suggesting the increased pressure of my new sealed system was not that
high and if existing system was working I'd be OK.

h) I mentioned past experience of combi boilers (over 12 years ago)
and he said the worcester 440 was miles ahead of whatever I had then
and I would not suffer from excessive reduced flow in winter. He did
go on quite a bit about what temperature my shower ran at and how I
was mixing alot of cold water with hot to get confortable.

i) he said my existing cylinder (although only 5 years old) was not up
to spec since it did not have 2" of insulation (I might have the exact
number wrong).

j) all (optional but included in his price) would be in the boiler
itself except for a room thermostat. He pointed out the problem with
having a room thermstat in the hall where the radiator had a TRV.

k) the worcester 440 had an in built 12l (I think) vessel which had
some advantage in the speed in which hot water reached my taps - not
sure exactly.

Cost £2600 (for combi boiler worcester 440 floor standing boiler,
replacement gas supply to boiler, ripping out / bypassing old system)
- sealed system.

o plumber number 2

quote not received yet but it was for a wall mounting Worcester 3XX
(something) 12l/min output at X degrees C rise (have not got the
brochure).

o concurred with plumber 1 than cylinder was not up to spec. Also said
the hot water feed to my shower pump was too high in the cylinder.
Also said the cylninder would be better turned through 90 degrees for
easier access to valve - fair enough.

o concurred with plumber 1 re TRV and room therm in same room.

o on business of 22mm gas feed to boiler - some needed it some don't -
often plumbers size up from 15 to 22 - a bit wishy washy - I was not
certain what was required but if a 22mm pipe was required as with
plumber 1 it could be run along outside wall.

o on combi boilers he would do a quote for both but a combi would be
more expensive since it required ripping out a lot of stuff - somewhat
at odds with plumber 1 who said the exact opposite.

o as with plumber 1 he'd need specs for ensuite shower valve as it
might not be up to increased standing pressure if we went combi boiler
but the myra shower valve in bathroom was certainly OK (I knew this
anyway as some tosser who previously installed shower in bathromm
before we moved here plumbed it in to the bath supply where the cold
water was mains pressure). When it leaked badly I needed to replace it
in a hurry and found I needed a more expensive valve to handle the
imbalance. Since then it has been replumbed to the cold tank.

o on combi boilers and my concern over loss of output in winter and at
my main ensuite shower he said it would cope so long as someone did
not use any water elsewhere in the house (whether cold or hot). He
recommended not having a combi boiler.

o servicing required for worcester 3XX was once every 12 to 18 months
and would cost around £50.

o room thermostat was required and they would not need to put cables
in as it was a (cableless) radio one.

o would quote for a powerflush at £395 which would take the best part
of a day as it involved connecting to heating system and flushing
through plus connecting to each radiator individually. When I
suggested this sounded alot (BG quoted £200) he said if the system had
been drained recently and was clean I could just ignore that in the
quote. They would have to drain the system twice anyway and lfush it
with some agent. He didn't try to sell it to me especially when I said
the system had been drained more than 5 times in the last 2 years
alone and drained out clean (also all of my radiators except one is
brand new).

o mains pressure was good in my area and not a worry.

o it cost them £5 to register the installation with Corgi who would
send me something I needed to keep as it would be required when I sold
my house.

o gas mains was being updated in my area since it fell off too much
(and caused some boilers to shut down) early in the morning when all
these new condensing boilers switched on.

What I think is a summary of the "true" bits of advice/information I
received from BG, local plumbers and this news group a

o you have to fit a condensing boiller unless you can amass 1000 pts
on a rather difficult to achieve scale. Certainly, a replacement
boiler is unlikey to achieve 1000 pts.

o plumning - I'm not going there - it seems a contentious issue.

o when moving to a condensing boiler you need a fully pumped system
(no gravity fed hot water) - this is law.

o don't have TRV on the radiator in the same room as a room thermostat
- also avoid rooms with other heat sources - kitchen, rooms with fires
etc Ed.

o condensing boilers produce condensate which is slightly acidic and
has to have somewhere to drain away.

o some boilers come with bypass valves, some don't. You can't go all
TRVs without a bypass valve.

o You need a "boiler interlock" that completely turns off the boiler
when the house is hot. Normally this is supplied by the room
thermostat. If there is none, another method must be used, such as a
flow switch on the heating circuit - thanks Christian/Andy/John.

o some condensing boilers are modulating so instead of a constant
power output they adjust to conditions. Minimum outout of boiler is
worht looking at.

o There should be electrical bonding from the meter to the main
earthing point in the house. The service bonding ought to be done on
the consumer side of the meter rather than the supply as used to be
the case.

o water cylinders are subject to building regs and upgrading a system
might (or must) mean upgrading the cylinder to current regs. Also, see
fast recovery cylinders (this was not mentioned to me by anyone
quoting).

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.

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.

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.

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.

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.

6. condensate from new boiler was not a problem since the boiler will
be sited next to a soil pipe.

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.

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.

9. It was around 3 days work.

10. the quote left has a "the effects of pluming have been explained"
but they never were.

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.

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).

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?

Martin

--
Martin J. Evans
Wetherby, UK