I had British Gas around last week to see if I could replace my
existing wall mounted boiler in the kitchen with a combi, allowing me
to ditch the ShowerMax in the bathroom.  They informed me that as of
April this year, all new Combi's must be condensing, which require a
22mm feed.  Unfortunately, my existing boiler has a 15mm feed, the 22mm
feed into the house, post meter, drops into the concrete floor in the
garage and at some stage before popping out the wall in the kitchen
changes to 15mm.

So it looks like I have two options, either:

a) Replace boiler in same position - will require digging up of
concrete ground floor to locate the start of the 15mm pipe.

b) Move boiler to garage - will require lifting of upstairs' floor
to redirect pipe work from bathroom.

I believe both options will require a vertical extended flue over 2m,
as distance of the existing/new horizontal flue terminal to
neighbouring boundary is/would be <2.5m.

Using the 'Guide to the Condensing Boiler Installation Assessment
Procedure for Dwellings'
(http://www.odpm.gov.uk/stellent/groups/odpm_buildreg/documents/page/odpm_breg_037022.pdf)
I calculated the 'cost' of these options to be:

a)	Detached 590  Extended  flue 200 = 790
b)	Detached 590  New boiler position 350  Extended flue 200 = 1140

Now, the guide states:

"It should be noted that when considering boiler locations for the
purposes of the assessment procedure, obstacles such as furniture and
fitments must be ignored."

My question is: Is my concrete ground floor considered as furniture or
fitments? i.e. would the relocation to the garage be considered the
"only feasible" option and with a cost >1000 would this mean I
would qualify for a non-condensing boiler?

I can't believe that the government expects anyone requiring a new
boiler to have to replace it with a condensing boiler at any
'monetary cost' because the 'assessment cost' is below 1000.

To add to the confusion, the British Gas guy was unaware of the new
2.5m minimum distance rule and still believed it to by 0.6m, he even
checked the documentation on his laptop, which he informed me, made no
reference to the new distance. This is a little worrying considering
British Gas have been fitting condensing boilers under the new
regulations for several months now.  He also said they could fit a
plume divertor terminal if it was going to be an issue, however, I
believe this would still be too close to my property boundary?

Any expert advice would be greatly appreciated as I am looking at
having to layout £3500 if I am forced to go down the condensing combi
route.

mmccar wrote:

> I had British Gas around last week to see if I could replace my
> existing wall mounted boiler in the kitchen with a combi, allowing me
> to ditch the ShowerMax in the bathroom.  They informed me that as of
> April this year, all new Combi's must be condensing, which require a
> 22mm feed.  


AIUI your existing boiler is not a combi? I don't know what a Showermax is.

The larger gas feed is required because the new boiler is a combi and 
has to provide instantaneous hot water, not because it's condensing.

If you think about it, a condensing boiler would require a *smaller* has 
feed for the same output, because it's more efficient.

New boilers must usually be condensing, but they don't have to be combi.

Owain

In article ,
	"mmccar"  writes:

>I had British Gas around last week to see if I could replace my
>existing wall mounted boiler in the kitchen with a combi, allowing me
>to ditch the ShowerMax in the bathroom.  They informed me that as of
>April this year, all new Combi's must be condensing, which require a
>22mm feed.  Unfortunately, my existing boiler has a 15mm feed, the 22mm


There's a mistake here. The larger pipe is because it's a combi,
and nothing to do with it being condensing.

-- 
Andrew Gabriel

"mmccar"  wrote in message 
news:1125399150.346097.26230@z14g2000cwz.googlegroups.com...
I had British Gas around last week to see if I could replace my
existing wall mounted boiler in the kitchen with a combi, allowing me
to ditch the ShowerMax in the bathroom.  They informed me that as of
April this year, all new Combi's must be condensing, which require a
22mm feed.  Unfortunately, my existing boiler has a 15mm feed, the 22mm
feed into the house, post meter, drops into the concrete floor in the
garage and at some stage before popping out the wall in the kitchen
changes to 15mm.

So it looks like I have two options, either:

a) Replace boiler in same position - will require digging up of
concrete ground floor to locate the start of the 15mm pipe.

b) Move boiler to garage - will require lifting of upstairs' floor
to redirect pipe work from bathroom.

I believe both options will require a vertical extended flue over 2m,
as distance of the existing/new horizontal flue terminal to
neighbouring boundary is/would be <2.5m.

Using the 'Guide to the Condensing Boiler Installation Assessment
Procedure for Dwellings'
(http://www.odpm.gov.uk/stellent/groups/odpm_buildreg/documents/page/odpm_breg_037022.pdf)
I calculated the 'cost' of these options to be:

a) Detached 590 + Extended  flue 200 = 790
b) Detached 590 + New boiler position 350 + Extended flue 200 = 1140

Now, the guide states:

"It should be noted that when considering boiler locations for the
purposes of the assessment procedure, obstacles such as furniture and
fitments must be ignored."

My question is: Is my concrete ground floor considered as furniture or
fitments? i.e. would the relocation to the garage be considered the
"only feasible" option and with a cost >1000 would this mean I
would qualify for a non-condensing boiler?

I can't believe that the government expects anyone requiring a new
boiler to have to replace it with a condensing boiler at any
'monetary cost' because the 'assessment cost' is below 1000.

To add to the confusion, the British Gas guy was unaware of the new
2.5m minimum distance rule and still believed it to by 0.6m, he even
checked the documentation on his laptop, which he informed me, made no
reference to the new distance. This is a little worrying considering
British Gas have been fitting condensing boilers under the new
regulations for several months now.  He also said they could fit a
plume divertor terminal if it was going to be an issue, however, I
believe this would still be too close to my property boundary?

Any expert advice would be greatly appreciated as I am looking at
having to layout 3500 if I am forced to go down the condensing combi
route.

Not too sure about the distance of the flue to the boundary: the problem 
with
condensing combis is that they put out large clouds of steam on some days as
the exhaust is so cool, and that would constitute a nuisance to a neighbour. 
If the
BG man can deflect the existing flue upward perhaps this will be ok, AKAIK 
the
issue of distance to boundary oly really applies for sideways facing flues. 
You can
dig the relevant regulations up on the web, some of the combi manufacturers 
have
them as .pdf files on their websites.
      As for the gas pipe, then if you are fitting a combi that is much more 
powerful
than your existing boiler ( a typical combi might be 28kW, I don't know what
power your existing boiler is ), then the feed pipe by rule of thumb needs 
to be
22mm to within 1metre of the combi, then 15mm is allowable for the last 
meter.
The reason is the pressure drop will be far too great if you use 15mm pipe 
for
the combi to work within specification. There are calculator websites 
available
on the web to help you work out the actual pressure drop, but certainly 15mm
will not do.

Andy.

Thanks everyone for your replies.

Andy, so if my 22mm pipe drops to 15mm within 1m of the boiler I may be
ok - I'm thinking the pipe change may be in the wall as opposed to the
under floor - any ideas what the standard practice is, is it even
permissible to lay concreate on a 15mm pipe?  Can I get a Corgi
engineer measure the pressure to see if the 15mm pipe will suffice?

Thanks everyone for your replies.

Andy, so if my 22mm pipe drops to 15mm within 1m of the boiler I may be
ok - I'm thinking the pipe change may be in the wall as opposed to
under the floor - any ideas what the standard practice is, is it even
permissible to lay concreate on a 15mm pipe?  Can I get a Corgi
engineer to measure the pressure to see if the 15mm pipe will suffice?

On 30 Aug 2005 03:52:30 -0700, "mmccar"
 wrote:


>I had British Gas around last week to see if I could replace my
>existing wall mounted boiler in the kitchen with a combi, allowing me
>to ditch the ShowerMax in the bathroom.  They informed me that as of
>April this year, all new Combi's must be condensing, which require a
>22mm feed.  Unfortunately, my existing boiler has a 15mm feed, the 22mm
>feed into the house, post meter, drops into the concrete floor in the
>garage and at some stage before popping out the wall in the kitchen
>changes to 15mm.


Not quite.  All new gas boilers must be condensing, unless you qualify
under the points system not to have one.




>
>So it looks like I have two options, either:
>
>a) Replace boiler in same position - will require digging up of
>concrete ground floor to locate the start of the 15mm pipe.


You are going to have to do something about the gas supply anyway. the
issue is the gas rate required by the combi - it is not an issue of
condensing or not.   Perhaps it is possible to do this with running a
new pipe other than through the floor?


>
>b) Move boiler to garage - will require lifting of upstairs' floor
>to redirect pipe work from bathroom.
>
>I believe both options will require a vertical extended flue over 2m,
>as distance of the existing/new horizontal flue terminal to
>neighbouring boundary is/would be <2.5m.


>
>Using the 'Guide to the Condensing Boiler Installation Assessment
>Procedure for Dwellings'
>(http://www.odpm.gov.uk/stellent/groups/odpm_buildreg/documents/page/odpm_breg_037022.pdf)
>I calculated the 'cost' of these options to be:
>
>a)	Detached 590 + Extended  flue 200 = 790
>b)	Detached 590 + New boiler position 350 + Extended flue 200 = 1140


Option a) would apply since it is possible to install in the existing
position.  For the purpose of the assessment, the lowest scored option
is used.  If you choose to re-site, that is your choice - you can't
use it to increase the points as you suggest in option (b)



>
>Now, the guide states:
>
>"It should be noted that when considering boiler locations for the
>purposes of the assessment procedure, obstacles such as furniture and
>fitments must be ignored."
>
>My question is: Is my concrete ground floor considered as furniture or
>fitments? i.e. would the relocation to the garage be considered the
>"only feasible" option and with a cost >1000 would this mean I
>would qualify for a non-condensing boiler?


It doesn't make any difference.



>
>I can't believe that the government expects anyone requiring a new
>boiler to have to replace it with a condensing boiler at any
>'monetary cost' because the 'assessment cost' is below 1000.
>


We live in a nanny state.  This is what people voted for.



>To add to the confusion, the British Gas guy was unaware of the new
>2.5m minimum distance rule and still believed it to by 0.6m, he even
>checked the documentation on his laptop, which he informed me, made no
>reference to the new distance. This is a little worrying considering
>British Gas have been fitting condensing boilers under the new
>regulations for several months now.  


He is looking at the safety requirement which is 0.6m.   The other is
only to avoid potential nuisance to the neighbour from a possible
plume.   With a very long flue, it is quite likely that there would
not be significant pluming anyway because much of the water vapour
would condense and run back to the boiler.



>He also said they could fit a
>plume divertor terminal if it was going to be an issue, however, I
>believe this would still be too close to my property boundary?
>


Two things here.

Look at other suppliers as well as BG and you will discover that they
are charging much more than most independent heating engineers - often
up to twice as much.

You could look at a boiler which will take twin plastic flues.  Quite
a number have this as an option and they are implemented using 50mm
muPVC high temperature waste pipe.   This gives a much neater and
cheaper solution for long runs, especially if you have to have some
gymnastics with the routing.



>Any expert advice would be greatly appreciated as I am looking at
>having to layout 3500 if I am forced to go down the condensing combi
>route.


It should be possible to do this for under 2000.  If you choose an
independent installer.   Much of the work will be with running a new
gas service which you'll need anyway and a new flue.   The difference
in boiler cost is not going to be great in the equation, so you might
as well have a condensing product and save on gas as well.  Roughly
speaking the comparison is between 80% vs 90% seasonal efficiency so
you should be able to achieve a payback within the lifetime of the
boiler.



-- 

..andy

To email, substitute .nospam with .gl

On 30 Aug 2005 05:59:40 -0700, "mmccar"
 wrote:


>Thanks everyone for your replies.
>
>Andy, so if my 22mm pipe drops to 15mm within 1m of the boiler I may be
>ok - I'm thinking the pipe change may be in the wall as opposed to the
>under floor - any ideas what the standard practice is, is it even
>permissible to lay concreate on a 15mm pipe?  Can I get a Corgi
>engineer measure the pressure to see if the 15mm pipe will suffice?


This is a bit difficult to do since the existing boiler is running at
a lower gas rate than the combi would. The point would be the pressure
drop from meter to boiler which must be no more than 1mB.  However
that has to be measured under load conditions.

You can calculate based on the guidelines at 

http://www.cda.org.uk/megab2/build/pub124/default.htm

Generally, if the 15mm run is about 1m, it should be OK as long as the
rest is 22mm.

It is common to use iron pipe in concrete, but the internal diameter
is only slightly more than 15mm copper, unfortunately.

Perhaps you could excavate near the boiler and see what the pipe is?

Copper pipe can be run in concrete provided that it is sleeved in some
way to prevent corrosion of the copper - a material issue not a size
one.




-- 

..andy

To email, substitute .nospam with .gl

mmccar wrote:


> Andy, so if my 22mm pipe drops to 15mm within 1m of the boiler I may be
> ok - I'm thinking the pipe change may be in the wall as opposed to
> under the floor - any ideas what the standard practice is, is it even
> permissible to lay concreate on a 15mm pipe?  Can I get a Corgi
> engineer to measure the pressure to see if the 15mm pipe will suffice?


To be sure, you wil need to do the sums. The first thing to find out is 
the maximum input gas rate of the boiler (it will be in the handbook, 
which you can download from the makers web site). Then use the CDA 
document that Andy posted a link to to see if your existing pipework 
will do the job.


-- 
Cheers,

John.

/=================================================================\
|          Internode Ltd -  http://www.internode.co.uk            |
|-----------------------------------------------------------------|
|        John Rumm - john(at)internode(dot)co(dot)uk              |
\=================================================================/

Andy Hall wrote:


> You are going to have to do something about the gas supply anyway. the
> issue is the gas rate required by the combi - it is not an issue of
> condensing or not.   Perhaps it is possible to do this with running a
> new pipe other than through the floor?


One commonly used solution these days is to run the gas pipe round the 
*outside* of the house, and just come back in near the boiler.


>>I believe both options will require a vertical extended flue over 2m,
>>as distance of the existing/new horizontal flue terminal to
>>neighbouring boundary is/would be <2.5m.


I think you can have less than 2.5m if required.


> He is looking at the safety requirement which is 0.6m.   The other is
> only to avoid potential nuisance to the neighbour from a possible
> plume.   With a very long flue, it is quite likely that there would
> not be significant pluming anyway because much of the water vapour
> would condense and run back to the boiler.


The longest "throw" of visble steam from the flue on my boiler 
(installed on the side of the house - pointing at the neighbours 
property some 2.2m away), is at most 400mm. So it does not even get as 
far as the boundary.


-- 
Cheers,

John.

/=================================================================\
|          Internode Ltd -  http://www.internode.co.uk            |
|-----------------------------------------------------------------|
|        John Rumm - john(at)internode(dot)co(dot)uk              |
\=================================================================/

Thank you all for your replies, got an independent installer coming
around next week, if we can't find distance of 22mm from boiler will
suggest running pipe round the outside of the house. :-)

In message , 
mmccar  writes

>I had British Gas around last week to see if I could replace my
>existing wall mounted boiler in the kitchen with a combi, allowing me
>to ditch the ShowerMax in the bathroom.  They informed me that as of
>April this year, all new Combi's must be condensing,


That's what the law says (with certain exceptions)


>
>Any expert advice would be greatly appreciated as I am looking at
>having to layout 3500 if I am forced to go down the condensing combi
>route.
>

First piece of advice

Don't go to British Gas unless you have more money than sense

Get some other quotes

-- 
geoff