C&G 6084 (Energy efficiency).
 

I thought one or two of you might be interested to know how I got on with
the 'Energy Efficiency Course'. (mandatory exam pass before 31/3/6
required to remain CORGI registered).

We had considerable discussion about several contentious issues.

1) The boiler sizing method makes no allowance for the draughtiness of the
home and will come up with (IMHO) too small a boiler if the assessment
procedures are used without thought.

2) Currently there is a massive culture of continuing to fit
non-condensing units claiming an exception where non are allowed.
Since the replacement of boilers is now notifiable this leads to a
problem. However on the CORGI web site for notifying the work (self
certified as complying) there are exemption codes to allow you to specify
that a regular boiler is compliant. Make of that what you sill.

3) Now this will please you know who - not.
We (That is at least three of the students) argued with the tutor when he
started to tell us that a 45litre super-fast [1] recovery cylinder could
provide continuous hot water enough to supply a 4 bar ST power shower. The
guy next to me said he'd just taken one out because it did not work. The
tutor said that he often had a fights almost break out over this subject.
The arguments became quite heated and caused the boss to come in to
reinforce the 'staff' who then made a you-know-who style declaration from
the sales brochure.

He said half a ton of water at 26.5 litre minute when connected to a 30kW
boiler with 35C rise. The cylinder initially at 60C. I carefully wrote
down his claim and then come lunch
time did calculations showed that this was plainly impossible. I sort of
guessed it was over the top but the calculations showed it was not even
close.

Afterwards he confided that whilst he agreed with my calculations he
wanted to get people thinking about the need to store less HW (with its
storage losses). I pointed out that the merits of fast recovery cylinders
don't need sales spin...

[1]
1" connection divides into a multiple-10mm microbore indirect coils
each of about 6 turns.


--
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

"Ed Sirett" wrote in message
n.co.uk...
I thought one or two of you might be interested to know how I got on with
the 'Energy Efficiency Course'. (mandatory exam pass before 31/3/6
required to remain CORGI registered).

Afterwards he confided that whilst he agreed with my calculations he
wanted to get people thinking about the need to store less HW (with its
storage losses).

Oh dear.

Storage losses on a highly insulated tank (Albion Mainsflow for example) are
low. And in any case most/all of the loss is to the house so you just don't
use the CH quite so much to make up. I would have thought having a boiler
frantically trying to modulate itself to one's use of the shower would be
far more inefficient.

Ed Sirett wrote:

I thought one or two of you might be interested to know how I got on with
the 'Energy Efficiency Course'. (mandatory exam pass before 31/3/6
required to remain CORGI registered).

We had considerable discussion about several contentious issues.

1) The boiler sizing method makes no allowance for the draughtiness of the
home and will come up with (IMHO) too small a boiler if the assessment
procedures are used without thought.

The method makes a number of other simplifying assumptions e.g. no allowance
for types of floor, and just adding the rad output for extensions, which
also seem quite wrong. We raised these issues and were told that they'd
been simplified out because they made little enough difference to the
requirement of the whole house that it didn't matter: our lecturer said
he'd been sceptical at first but had checked the figures against
traditional methods and convinced himself.

Looking at the figures for a house I did recently the vent loss was about
1/6th of the fabric loss, so this also seems a reasonable simplification. I
suppose a house would have to be pathologically draughty (like no glass in
the windows!) to seriously skew the figures.


2) Currently there is a massive culture of continuing to fit
non-condensing units claiming an exception where non are allowed.
Since the replacement of boilers is now notifiable this leads to a
problem. However on the CORGI web site for notifying the work (self
certified as complying) there are exemption codes to allow you to specify
that a regular boiler is compliant. Make of that what you sill.

I thought there were only exemptions for contracts (ahem!) "agreed" before
1/4/5 (which have to be completed by 1/7/5) and replacement under warranty.
Something like 7777 and 8888.



BTW where did you do yours?

"Ed Sirett" wrote in message
n.co.uk...

I thought one or two of you might be interested to know how I got on with
the 'Energy Efficiency Course'. (mandatory exam pass before 31/3/6
required to remain CORGI registered).

We had considerable discussion about several contentious issues.

1) The boiler sizing method makes no allowance for the draughtiness of the
home and will come up with (IMHO) too small a boiler if the assessment
procedures are used without thought.

2) Currently there is a massive culture of continuing to fit
non-condensing units claiming an exception where non are allowed.
Since the replacement of boilers is now notifiable this leads to a
problem. However on the CORGI web site for notifying the work (self
certified as complying) there are exemption codes to allow you to specify
that a regular boiler is compliant. Make of that what you sill.

3) Now this will please you know who - not.
We (That is at least three of the students) argued with the tutor when he
started to tell us that a 45litre super-fast [1] recovery cylinder could
provide continuous hot water enough to supply a 4 bar ST power shower. The
guy next to me said he'd just taken one out because it did not work.

What did not work?

The tutor said that he often had a fights almost break out over this
subject.
The arguments became quite heated and caused the boss to come in to
reinforce the 'staff' who then made a you-know-who style declaration from
the sales brochure.

He said half a ton of water at 26.5 litre minute when connected to a 30kW
boiler with 35C rise. The cylinder initially at 60C. I carefully wrote
down his claim and then come lunch
time did calculations showed that this was plainly impossible. I sort of
guessed it was over the top but the calculations showed it was not even
close.

It could be close if the temperature on the inlet water is very high.

Ballpark is that 30kW will deliver about 12-13 l/m of instant hot water @
35C temp rise. If there is 45 litres of hot water stored at 60C and the
coil takes all of the boilers output, then to be infinitely continuous, the
shower must be not more than 13 l/min. Anything over this and the hot water
in the cylinder will gradually deplete. It will fill an average bath OK,
then run out of hot water. Depending on how the coil is arranged inside the
cylinder, it could drop back to about 12 l/min and never run cold.

Afterwards he confided that whilst he agreed with my calculations he
wanted to get people thinking about the need to store less HW (with its
storage losses). I pointed out that the merits of fast recovery cylinders
don't need sales spin...

They do. Few people use them. One old hand on a plumbers merchants counter
I know had never even heard of them.

[1]
1" connection divides into a multiple-10mm microbore indirect coils
each of about 6 turns.


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Mike wrote:

"Ed Sirett" wrote in message
n.co.uk...
I thought one or two of you might be interested to know how I got on with
the 'Energy Efficiency Course'. (mandatory exam pass before 31/3/6
required to remain CORGI registered).

Afterwards he confided that whilst he agreed with my calculations he
wanted to get people thinking about the need to store less HW (with its
storage losses).

Oh dear.

Storage losses on a highly insulated tank (Albion Mainsflow for example) are
low. And in any case most/all of the loss is to the house so you just don't

Not to mention that a roll of loft insulation wrapped round the tank seriously
helps the numbers too.

In article , John Stumbles
wrote:
Looking at the figures for a house I did recently the vent loss was
about 1/6th of the fabric loss, so this also seems a reasonable
simplification. I suppose a house would have to be pathologically
draughty (like no glass in the windows!) to seriously skew the
figures.

On the model detached house we use to check our SuperHeat program the
ventilation rate used in the SAP worksheet is 0.81 ach and the
ventilation heat loss (fabric to current BR standards) is 38% of the
total. Obviously as you make the fabric standards tighter and tighter
the ventilation loss as a proportion of the whole tends to increase,
which is why there is now a lot more emphasis on 'build tight, ventilate
right' and possible compulsory pressure testing of new dwellings.

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm
[Latest version QSEDBUK 1.10 released 4 April 2005]

On Mon, 23 May 2005 22:40:06 +0000, John Stumbles wrote:

Ed Sirett wrote:

I thought one or two of you might be interested to know how I got on with
the 'Energy Efficiency Course'. (mandatory exam pass before 31/3/6
required to remain CORGI registered).

We had considerable discussion about several contentious issues.

1) The boiler sizing method makes no allowance for the draughtiness of the
home and will come up with (IMHO) too small a boiler if the assessment
procedures are used without thought.

The method makes a number of other simplifying assumptions e.g. no allowance
for types of floor, and just adding the rad output for extensions, which
also seem quite wrong. We raised these issues and were told that they'd
been simplified out because they made little enough difference to the
requirement of the whole house that it didn't matter: our lecturer said
he'd been sceptical at first but had checked the figures against
traditional methods and convinced himself.

Looking at the figures for a house I did recently the vent loss was about
1/6th of the fabric loss, so this also seems a reasonable simplification. I
suppose a house would have to be pathologically draughty (like no glass in
the windows!) to seriously skew the figures.


2) Currently there is a massive culture of continuing to fit
non-condensing units claiming an exception where non are allowed.
Since the replacement of boilers is now notifiable this leads to a
problem. However on the CORGI web site for notifying the work (self
certified as complying) there are exemption codes to allow you to specify
that a regular boiler is compliant. Make of that what you sill.

I thought there were only exemptions for contracts (ahem!) "agreed" before
1/4/5 (which have to be completed by 1/7/5) and replacement under warranty.
Something like 7777 and 8888.



BTW where did you do yours?

1st Training (Nr. Huntingdon).

--
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