Hi all,

This boiler choice FAQ is nearly twice the size of the original and
has incorporated a number but not all of suggestions.

Phil - you may certainly add this to the main FAQ site. However there are
still some hopefully small edits needed.

Anyone know where the simplified boiler sizing estimator from the SAP of
the building regs can be found?

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

On Tue, 03 Jan 2006 23:45:01 +0000, Ed Sirett wrote:

Anyone know where the simplified boiler sizing estimator from the SAP of
the building regs can be found?

Either of these what you're looking for?

http://www.est.org.uk/housingbuildin.../boilersizing/

http://www.idhe.org.uk/calculator.html


I also have a spreadsheet that does it (correctly, AFAICT, unlike at least
one if the above - unless they've fixed it since I complained to them).

On Tue, 03 Jan 2006 23:45:01 +0000, Ed Sirett wrote:

Hi all,

This boiler choice FAQ is nearly twice the size of the original and
has incorporated a number but not all of suggestions.

Great stuff: thanks for your work on this Ed.

There are a few rough edges and typos which I'm assuming you'll fix, but
here are a few more substantial points I hope you'll consider.


"2. Help! Help! The boiler has died! What Next?
....
The fear of having a cold house in winter can push some people to make
unwise or hasty decisions"

Even if the boiler hasn't died .... I had an email discussion with a
client along these lines:

The British Gas man has just serviced the boiler and ... they have
said that if, e.g. any there is any problem with
the case, the flue or the heat exchanger then there are no parts
available for this heater,..... anywhere. ( Potterton Netaheat 10 - 16
( Mk II F ) )

Now, is this scaremongering or fact?

Both :-)

I daresay none of those parts is avalable any longer, but none is
particularly likely to fail either (although cases and heat exchangers
do eventually corrode, so it's curtains for the boiler if that happens).
Parts that are more likely to fail are the fan, PCB and gas valve, all
of which are readily available

To put it in perspective there are failures which can occur on fairly
new boilers which can put them out of action for 2-3 (working) days
while one gets new parts, which isn't a lot less bad if it happens on a
Friday evening in the depths of winter than needing a whole new boiler
(which can be installed in a couple of days).

I think the best preparation is to have a supply of warm woolies, hot
water bottles and a couple of electric radiators or fan heaters. You can
borrow or buy more heaters if you know you'll need them for a few days
or even a week or two, and a modern, well-insulated house like yours
won't cost a fortune to heat even with peak-rate electricity. I think
you've got an electric immersion heater in your hot water cylinder,
haven't you? So you wouldn't be without hot water. That would save you
being panicked into paying through the nose for an emergency boiler
repair or replacement.

Where you say:
"If you have a stored HW system you can turn the electric immersion heater
on (if the original installer added one!)"
maybe add: "or even install one to get hot water immediately
(especially if you would be keeping the stored HW system even if you were
replacing the boiler)."



"3. Why can’t I have ‘old faithful’ back again?
....
[Footnote: There is an exemption procedure but unless you have a
back-boiler in a terraced house or flat you can forget it.]."

This reads (to me) that you have to have a back boiler (in either a
house or a flat) to get an exemption. How about rewording as:
"There is an exemption procedure but unless you are in a
flat or have a back-boiler in a terraced house you can forget
it.]."



"6 Conservatory type extensions also must be an independent heating zone."
Where did you get this from? I haven't scoured the ADs but I don't recall
it.


The next point is a bit OT to the FAQ.
"For non-combi boiler systems where there is stored HW you also will need:
1. Independent time control for the heating of HW.
2. Temperature control of the HW (usually done by a cylinder thermostat)."

I phoned Gledhill today but forgot to ask about this. I've just done a job
at a flat with a Boilermate installed in it, and that has no time control
on the DHW. I'm not sure it even has a temp control. I wonder what the
position is there?

Ed Sirett wrote:

This boiler choice FAQ is nearly twice the size of the original and
has incorporated a number but not all of suggestions.

Nice work Ed.

A few odd bits that jumped out:

"As a rough rule of thumb using 2005 figures I estimate any repair of
less than £100 is worth doing. For a boiler less than 20 years old you
may want to allow a bit more on a sliding scale so that with a younger
boiler you are prepared to much more for its repair"

Seems like you need a "spend" toward the end of that.

"The condensate is slightly acidic same as fruit juice it might just rot
a metal pipe given time but not overnight."

Needs a comma or perhaps a "the" in there.

"This is not a disadvantage nearly always there is more wall space than
floor space."

"since nearly always"?

Very end of section 5 you have a embedded br tag after the end
paragrapoh tag /p - that upsets the formatting (causing the end of the
sentance to be chopped) when the font sizes are increased in Mozilla.

On the flue location bit toward the end of chapter 8, might it be worth
including the building regs minimum distance (600mm?) from a boundary as
well as your recommendation for 2.5m as a distance that ought to
completely avoid the issue?

"The third group obvious have relatively little influence"

"obviously"?

Glossary:

"A feature where the boiler can alters it power output usually to suit
conditions."

"alter"?

"The cloud of steam (actually a mist of tiny water droplets) often seen
coming out of a condensing boiler flue in cold damp weather. "

"cold dry weather" would cause a more noticable effect would it not?

"or electromagnetically bewitching the input mains water (efficacy
uncertain)." LOL - I like that turn of phrase!





--
Cheers,

John.

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

On Wed, 04 Jan 2006 00:20:55 +0000, John Stumbles wrote:

On Tue, 03 Jan 2006 23:45:01 +0000, Ed Sirett wrote:

Anyone know where the simplified boiler sizing estimator from the SAP of
the building regs can be found?

Either of these what you're looking for?

http://www.est.org.uk/housingbuildin.../boilersizing/


broken for me. 8-(


http://www.idhe.org.uk/calculator.html


That'll do nicely.


I also have a spreadsheet that does it (correctly, AFAICT, unlike at least
one if the above - unless they've fixed it since I complained to them).
--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

On Wed, 04 Jan 2006 01:11:45 +0000, John Stumbles wrote:

On Tue, 03 Jan 2006 23:45:01 +0000, Ed Sirett wrote:

Hi all,

This boiler choice FAQ is nearly twice the size of the original and
has incorporated a number but not all of suggestions.

Great stuff: thanks for your work on this Ed.

There are a few rough edges and typos which I'm assuming you'll fix, but
here are a few more substantial points I hope you'll consider.


"2. Help! Help! The boiler has died! What Next?
...
The fear of having a cold house in winter can push some people to make
unwise or hasty decisions"

Even if the boiler hasn't died .... I had an email discussion with a
client along these lines:

The British Gas man has just serviced the boiler and ... they have
said that if, e.g. any there is any problem with
the case, the flue or the heat exchanger then there are no parts
available for this heater,..... anywhere. ( Potterton Netaheat 10 - 16
( Mk II F ) )

Now, is this scaremongering or fact?

Both :-)

I daresay none of those parts is avalable any longer, but none is
particularly likely to fail either (although cases and heat exchangers
do eventually corrode, so it's curtains for the boiler if that happens).
Parts that are more likely to fail are the fan, PCB and gas valve, all
of which are readily available

To put it in perspective there are failures which can occur on fairly
new boilers which can put them out of action for 2-3 (working) days
while one gets new parts, which isn't a lot less bad if it happens on a
Friday evening in the depths of winter than needing a whole new boiler
(which can be installed in a couple of days).

I think the best preparation is to have a supply of warm woolies, hot
water bottles and a couple of electric radiators or fan heaters. You can
borrow or buy more heaters if you know you'll need them for a few days
or even a week or two, and a modern, well-insulated house like yours
won't cost a fortune to heat even with peak-rate electricity. I think
you've got an electric immersion heater in your hot water cylinder,
haven't you? So you wouldn't be without hot water. That would save you
being panicked into paying through the nose for an emergency boiler
repair or replacement.
4
Where you say:
"If you have a stored HW system you can turn the electric immersion heater
on (if the original installer added one!)"
maybe add: "or even install one to get hot water immediately
(especially if you would be keeping the stored HW system even if you were
replacing the boiler)."

I didn't want to encourage peoples hopes too much here. It may well be
possible to add one, but there may be no electrical supply. Also it may
not be possible to get the blanking plug out with out destroying the
cylinder.

About 12 month ago this happen to a customer, I was able to replace the
failed immersion and check the gas fire over and so buy a few days time
for the replacement.




"3. Why cant I have €˜old faithful back again?
...
[Footnote: There is an exemption procedure but unless you have a
back-boiler in a terraced house or flat you can forget it.]."

This reads (to me) that you have to have a back boiler (in either a
house or a flat) to get an exemption. How about rewording as:
"There is an exemption procedure but unless you are in a
flat or have a back-boiler in a terraced house you can forget
it.]."

No really, AIUI, if you look at the procedure more or less you need a
back-boiler AND a flat or terraced house. A back-boiler in a semi won't
cut it. A flat might do it if the drain is difficult but it probably won't
be.

"6 Conservatory type extensions also must be an independent heating
zone." Where did you get this from? I haven't scoured the ADs but I
don't recall it.

Isn't it about the fact that conservatories are not meant to be year round
habitable spaces. It's something I picked up. It's certainly best practice
even if not mandatory. Since there is some uncertainty I'll just drop it
out.



The next point is a bit OT to the FAQ. "For non-combi boiler systems
where there is stored HW you also will need:
1. Independent time control for the heating of HW. 2. Temperature
control of the HW (usually done by a cylinder thermostat)."

I phoned Gledhill today but forgot to ask about this. I've just done a
job at a flat with a Boilermate installed in it, and that has no time
control on the DHW. I'm not sure it even has a temp control. I wonder
what the position is there?

Does the CH come form the boiler or form the store?
I'll, just change it to a HW cylinder (for which the comment is certainly
true).

Part of my motivation for the work was that I'd be able to use it for
'work'. At the back of my mind this FAQ was written with a view to trying to
persuade, perhaps an older customer, that is very happy with the existing
setup why a lot of things have to be changed.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

On Wed, 04 Jan 2006 03:46:13 +0000, John Rumm wrote:

Ed Sirett wrote:

This boiler choice FAQ is nearly twice the size of the original and
has incorporated a number but not all of suggestions.

Nice work Ed.
Ta!


A few odd bits that jumped out:

"As a rough rule of thumb using 2005 figures I estimate any repair of
less than £100 is worth doing. For a boiler less than 20 years old you
may want to allow a bit more on a sliding scale so that with a younger
boiler you are prepared to much more for its repair"

Seems like you need a "spend" toward the end of that.

"The condensate is slightly acidic same as fruit juice it might just rot
a metal pipe given time but not overnight."

Needs a comma or perhaps a "the" in there.

"This is not a disadvantage nearly always there is more wall space than
floor space."

"since nearly always"?

Very end of section 5 you have a embedded br tag after the end
paragrapoh tag /p - that upsets the formatting (causing the end of the
sentance to be chopped) when the font sizes are increased in Mozilla.

All the above accepted with thanks.


On the flue location bit toward the end of chapter 8, might it be worth
including the building regs minimum distance (600mm?) from a boundary as
well as your recommendation for 2.5m as a distance that ought to
completely avoid the issue?

I check on the ODPM site they are saying 2.5m either as the rules or as a
proposed amendment, I was unable to work out which.
The 600mm would be from the installation manual and typically would be
repeat the contents of BS 5440. I.e 600mm to face a wall or fence and
1200mm to another terminal.

In practice I take into account all sort of factors like:
How they get on with the current neighbours.
Which boiler might be fitted and what bits are available. Does the
neighbour have a pluming flue already fitted.





"The third group obvious have relatively little influence"

"obviously"?


Glossary:

"A feature where the boiler can alters it power output usually to suit
conditions."

"alter"?

"The cloud of steam (actually a mist of tiny water droplets) often seen
coming out of a condensing boiler flue in cold damp weather. "

"cold dry weather" would cause a more noticable effect would it not?
In dry weather which in winter is usually cold weather the plume
dissipates but in damp still conditions (Foggy weather) it lingers.
However the two effects might well work against each other so I'll just
say "cold weather".


"or electromagnetically bewitching the input mains water (efficacy
uncertain)." LOL - I like that turn of phrase!

As Terry Pratchett says: "Writing is as much fun as anyone can have by
themselves." My favourite bit is the "Hades Utopia 80 CF" anyone in the
game will picture exactly the model of boiler I mean.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

On Wed, 04 Jan 2006 18:27:57 +0000, Ed Sirett wrote:

On Wed, 04 Jan 2006 00:20:55 +0000, John Stumbles wrote:

http://www.idhe.org.uk/calculator.html


That'll do nicely.

Unfortunately it still seems to me to be broken. If a mid-floor flat is
specified then there should be no heatloss factor for the roof, but the
results show a non-zero figure for "ROOF heat loss". If one changes the
type of roof (e.g. thickness of insulation) then this factor (and
consequently the reported boiler size required) changes.

My spreadsheet is at http://82.24.138.95/~john/boiler_sizing.xls (or
http://82.24.138.95/~john/boiler_sizing.sxc if you have OpenOffice)

On Wed, 04 Jan 2006 18:50:15 +0000, Ed Sirett wrote:

On Wed, 04 Jan 2006 01:11:45 +0000, John Stumbles wrote:

On Tue, 03 Jan 2006 23:45:01 +0000, Ed Sirett wrote:


Where you say:
"If you have a stored HW system you can turn the electric immersion heater
on (if the original installer added one!)"
maybe add: "or even install one to get hot water immediately
(especially if you would be keeping the stored HW system even if you were
replacing the boiler)."

I didn't want to encourage peoples hopes too much here. It may well be
possible to add one, but there may be no electrical supply.

I suppose it would have the Part P-p-p-police down on us like a ton of
bricks to even think of plugging it into a 13A socket, pro tem.... ?

Also it may
not be possible to get the blanking plug out with out destroying the
cylinder.

True, but that may happen with replacing an existing immersion heater too.
And in these circumstances at least it doesn't leave the customer without
HW which they had before :-)


About 12 month ago this happen to a customer, I was able to replace the
failed immersion and check the gas fire over and so buy a few days time
for the replacement.

The point I was trying to make was that getting a new boiler is a pretty
significant expenditure, and an opportunity to change other aspects
of the ch + dwh system to better suit the users (e.g. conventional -
combi or combi - mains pressure stored hw), so one oughtn't rush into it
just because it's cold outside (or even inside!). Spending even a few
£100 on electric heating for a few weeks may pay off if one then ends up
with the right system.


"3. Why can’t I have ‘old faithful’ back again?
...
[Footnote: There is an exemption procedure but unless you have a
back-boiler in a terraced house or flat you can forget it.]."

This reads (to me) that you have to have a back boiler (in either a
house or a flat) to get an exemption. How about rewording as:
"There is an exemption procedure but unless you are in a
flat or have a back-boiler in a terraced house you can forget
it.]."

No really, AIUI, if you look at the procedure more or less you need a
back-boiler AND a flat or terraced house. A back-boiler in a semi won't
cut it. A flat might do it if the drain is difficult but it probably won't
be.

My C&G 6084 tutor pointed out that in some flats there's just nowhere
to site a condi where the flue isn't too close to the boundary.
Also I'm not sure I've even seen a bb in a flat, but I suppose there
must be some.



"6 Conservatory type extensions also must be an independent heating
zone." Where did you get this from? I haven't scoured the ADs but I
don't recall it.

Isn't it about the fact that conservatories are not meant to be year round
habitable spaces. It's something I picked up. It's certainly best practice
even if not mandatory. Since there is some uncertainty I'll just drop it
out.

Or how about putting in what you've just said? It's useful info.


The next point is a bit OT to the FAQ. "For non-combi boiler systems
where there is stored HW you also will need:
1. Independent time control for the heating of HW. 2. Temperature
control of the HW (usually done by a cylinder thermostat)."

I phoned Gledhill today but forgot to ask about this. I've just done a
job at a flat with a Boilermate installed in it, and that has no time
control on the DHW. I'm not sure it even has a temp control. I wonder
what the position is there?

Does the CH come form the boiler or form the store?
I'll, just change it to a HW cylinder (for which the comment is certainly
true).

Well as I said it's OT to the FAQ - I should prolly have put my comment in
a separate post really. It's just that what you said reminded me of this
question that had occured to me when I'd seen the Boilermate installation.
The CH comes off the thermal store so I guess there's an argument that the
store becomes part of the boiler system (like the thermal store inside a
storage combi) but I'd like to see what Gledhill say about it. They're
supposed to be sending me a manual for it so I'll wait to see what that
says. As regards the FAQ however I think this sort of arrangement is so
unusual it doesn't qualify for the 'F' part :-)


Part of my motivation for the work was that I'd be able to use it for
'work'. At the back of my mind this FAQ was written with a view to trying to
persuade, perhaps an older customer, that is very happy with the existing
setup why a lot of things have to be changed.

I can see myself pointing folks in that direction too!

On Thu, 05 Jan 2006 00:44:19 +0000, John Stumbles wrote:

On Wed, 04 Jan 2006 18:50:15 +0000, Ed Sirett wrote:

On Wed, 04 Jan 2006 01:11:45 +0000, John Stumbles wrote:

On Tue, 03 Jan 2006 23:45:01 +0000, Ed Sirett wrote:


Where you say:
"If you have a stored HW system you can turn the electric immersion heater
on (if the original installer added one!)"
maybe add: "or even install one to get hot water immediately
(especially if you would be keeping the stored HW system even if you were
replacing the boiler)."

I didn't want to encourage peoples hopes too much here. It may well be
possible to add one, but there may be no electrical supply.

I suppose it would have the Part P-p-p-police down on us like a ton of
bricks to even think of plugging it into a 13A socket, pro tem.... ?

Never thought of doing that mate! wink


Also it may
not be possible to get the blanking plug out with out destroying the
cylinder.

True, but that may happen with replacing an existing immersion heater too.
And in these circumstances at least it doesn't leave the customer without
HW which they had before :-)



About 12 month ago this happen to a customer, I was able to replace the
failed immersion and check the gas fire over and so buy a few days time
for the replacement.

The point I was trying to make was that getting a new boiler is a pretty
significant expenditure, and an opportunity to change other aspects
of the ch + dwh system to better suit the users (e.g. conventional -
combi or combi - mains pressure stored hw), so one oughtn't rush into it
just because it's cold outside (or even inside!). Spending even a few
£100 on electric heating for a few weeks may pay off if one then ends up
with the right system.

Quite, this is more or less what the FAQ says.
In my experience may people don't even know they have an immersion until
you point it out.



"3. Why cant I have €˜old faithful back again?
...
[Footnote: There is an exemption procedure but unless you have a
back-boiler in a terraced house or flat you can forget it.]."

This reads (to me) that you have to have a back boiler (in either a
house or a flat) to get an exemption. How about rewording as:
"There is an exemption procedure but unless you are in a
flat or have a back-boiler in a terraced house you can forget
it.]."

No really, AIUI, if you look at the procedure more or less you need a
back-boiler AND a flat or terraced house. A back-boiler in a semi won't
cut it. A flat might do it if the drain is difficult but it probably won't
be.

My C&G 6084 tutor pointed out that in some flats there's just nowhere
to site a condi where the flue isn't too close to the boundary.
Also I'm not sure I've even seen a bb in a flat, but I suppose there
must be some.

According to the ODPM the angle of the flue should be taken into account.
So if the flue's straight out through the wall even if it's close to the
boundary there shouldn't be a problem.

Round here there is an estate of 1950s partly ex council housing where
BBUs were installed about 25 years. These are low rise blocks of flats.



--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

John Stumbles wrote:

Unfortunately it still seems to me to be broken. If a mid-floor flat is
specified then there should be no heatloss factor for the roof, but the
results show a non-zero figure for "ROOF heat loss". If one changes the
type of roof (e.g. thickness of insulation) then this factor (and
consequently the reported boiler size required) changes.

My spreadsheet is at http://82.24.138.95/~john/boiler_sizing.xls (or
http://82.24.138.95/~john/boiler_sizing.sxc if you have OpenOffice)


Seems to be broken on your spreadsheet too. (OO version).


--
David Clark

$message_body_include ="PLES RING IF AN RNSR IS REQIRD"

On Tue, 03 Jan 2006 23:45:01 +0000, in uk.d-i-y Ed Sirett
wrote:

Hi all,

This boiler choice FAQ is nearly twice the size of the original and
has incorporated a number but not all of suggestions.

Phil - you may certainly add this to the main FAQ site. However there are
still some hopefully small edits needed.

Ok, let me know when you have finished your updates. I think you said
you are working in Word doc, in which case it's best if you give me your
doc file to put into FAQ css style.

Phil
The uk.d-i-y FAQ is at http://www.diyfaq.org.uk/
The Google uk.d-i-y archive is at http://tinyurl.com/65kwq
Remove NOSPAM from address to email me

On Thu, 05 Jan 2006 19:46:58 +0000, Phil Addison wrote:

On Tue, 03 Jan 2006 23:45:01 +0000, in uk.d-i-y Ed Sirett
wrote:

Hi all,

This boiler choice FAQ is nearly twice the size of the original and
has incorporated a number but not all of suggestions.

Phil - you may certainly add this to the main FAQ site. However there are
still some hopefully small edits needed.

Ok, let me know when you have finished your updates. I think you said
you are working in Word doc, in which case it's best if you give me your
doc file to put into FAQ css style.


I've spotted a few more typos. which I'm fixing now.
The main text was written using open office (an Office clone).
But it was always saved/opened in HTML.
The link fixing was done in Mozilla's composer.

What you see is what I have.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://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
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

On Thu, 05 Jan 2006 10:41:12 +0000, Ed Sirett wrote:

On Thu, 05 Jan 2006 00:44:19 +0000, John Stumbles wrote:

On Wed, 04 Jan 2006 18:50:15 +0000, Ed Sirett wrote:

On Wed, 04 Jan 2006 01:11:45 +0000, John Stumbles wrote:

On Tue, 03 Jan 2006 23:45:01 +0000, Ed Sirett wrote:

In my experience may people don't even know they have an immersion until
you point it out.

Too true: came across a brand spanking new upmarket flat with an Ideal
I-whateveritscalled boiler+unvented cyl and the immersion was switched on
full time, presumably because it was on an unlabelled neon switch next to
the FCU which it seemed obvious to switch on.


My C&G 6084 tutor pointed out that in some flats there's just nowhere
to site a condi where the flue isn't too close to the boundary. Also
I'm not sure I've even seen a bb in a flat, but I suppose there must be
some.

According to the ODPM the angle of the flue should be taken into
account. So if the flue's straight out through the wall even if it's
close to the boundary there shouldn't be a problem.

True, but to put a condensing flue through the wall of the
kitchen of a flat which is next door to - and about 1m away from the
window of - the lounge of the flat next door then that's quite likely
to wind up the nieigbours. I think that's what our tutor was getting at.

On Thu, 05 Jan 2006 14:24:55 +0000, DJC wrote:

John Stumbles wrote:

Unfortunately it still seems to me to be broken. If a mid-floor flat is
specified then there should be no heatloss factor for the roof, but the
results show a non-zero figure for "ROOF heat loss". If one changes the
type of roof (e.g. thickness of insulation) then this factor (and
consequently the reported boiler size required) changes.

My spreadsheet is at http://82.24.138.95/~john/boiler_sizing.xls (or
http://82.24.138.95/~john/boiler_sizing.sxc if you have OpenOffice)


Seems to be broken on your spreadsheet too. (OO version).

How do you mean?

Not in respect of the roof of the flat - if you don't put a 1 in any of
the roof options boxes then the 'roof heat loss' figure (cell B18) is 0.

I _think_ I've got the calculations right, but if you can show me that
I've got them wrong somewhere I'll be very happy and keen to fix it.

Unlike the folks at idhe.org.uk who simply ignored my email in
which I pointed out the error I think I found on theirs.

John Stumbles wrote:
On Thu, 05 Jan 2006 14:24:55 +0000, DJC wrote:
John Stumbles wrote:
My spreadsheet is at http://82.24.138.95/~john/boiler_sizing.xls (or
http://82.24.138.95/~john/boiler_sizing.sxc if you have OpenOffice)

Seems to be broken on your spreadsheet too. (OO version).

How do you mean?

Not in respect of the roof of the flat - if you don't put a 1 in any of
the roof options boxes then the 'roof heat loss' figure (cell B18) is 0.

Perhaps it is just rather confusing then; a case of the user interface
rather than the calculation itself. A note that putting 0 in the roof
section is an option rather than "Put '1' in one of these boxes"

Perhaps as the the roof calc is conditional on B9 being 1, a note to
the effect that "Nr. of external walls,roof,floor" can be modified from
the default. I realise a roof and a ceiling are not the same thing but
these things do confuse, even if the roof is not imediately below my
flat I still have a roof over my head.(Is there always a floor value for
a flat or does floor in this case mean ground floor?)
Also I need to set the window factor to 0.35 rather than 1 to make
window area represent my window area, And External walls 1.5 allowing
for the stairwell in common parts.
Water heating default is 2000kW, not 2kW?

Depending on how I interpret the required input my results vary from
4.6kW to over 7kW.

[No matter in my case, as that's less than the lowest modulated output
of my combi.]



--
David Clark

$message_body_include ="PLES RING IF AN RNSR IS REQIRD"

On Fri, 06 Jan 2006 01:06:52 +0000, DJC wrote:

John Stumbles wrote:
On Thu, 05 Jan 2006 14:24:55 +0000, DJC wrote:
John Stumbles wrote:
My spreadsheet is at http://82.24.138.95/~john/boiler_sizing.xls (or
http://82.24.138.95/~john/boiler_sizing.sxc if you have OpenOffice)

Seems to be broken on your spreadsheet too. (OO version).

Perhaps it is just rather confusing then; a case of the user interface
rather than the calculation itself. A note that putting 0 in the roof
section is an option rather than "Put '1' in one of these boxes"

User interface?!!! :-)

It was never meant to be particularly user-friendly, just something I
knocked up for myself to do the calcs to my own satisfaction. I thought
I'd better put in some explanatory notes if I was going to put it up for
others to use, but thanks anyway on how I could explain it better. However
it does really presuppose an understanding of the method, which I think
is described on one of the sites I mentioned in my post in reply to Ed's
about the boiler FAQ.

Perhaps as the the roof calc is conditional on B9 being 1, a note to
the effect that "Nr. of external walls,roof,floor" can be modified from
the default. I realise a roof and a ceiling are not the same thing but
these things do confuse, even if the roof is not imediately below my
flat I still have a roof over my head.(Is there always a floor value for
a flat or does floor in this case mean ground floor?)

Ground floor: this is a simplified calculation which ignores heat losses
through party walls etc assuming that adjacent buildings will be equal
temperature. I was skeptical at first about many of the simplifying
assumptions but it seems that whoever devised this method have checked it
out reasonably well and made sure that the simplifications involve
small enough errors that the overall results are still valid.

Also I need to set the window factor to 0.35 rather than 1 to make
window area represent my window area

I'm not clear what you mean about the window factor - the value for a flat
is 0.25, which is what you should set.

... And External walls 1.5 allowing
for the stairwell in common parts.

I'd treat the stairwell as external unless it's well heated.

The point about this method is it is simplified so don't try and fine-tune
it for your particular place: if you want a more accurate calculation you
can do a full heat-loss calc for each room as per the Myson or Barlo
calculators (I also have a spreadsheet I use to do this but I wouldn't
dream of exposing it to public scrutiny!)


Water heating default is 2000kW, not 2kW?

Oops, yes.


Depending on how I interpret the required input my results vary from
4.6kW to over 7kW.

[No matter in my case, as that's less than the lowest modulated output
of my combi.]