Having looked at various replies to the question' How do I work out what
size boiler I require?' it's noticeable that many take the form of 'I
haven't trained as a heating engineer for 30 years to tell you how to do
it for free! Get yourself a book or go to college.' What's wrong with
doing a bit of research when you're going to spend £2000+. If they don't
want to help, why don't they just mind their own business? Oh and is
there anyone who has some pointers? I've tried a 'Whole house
calculator' for my semi and it comes out at 7.7KWs, which seems low but
then I'm not an expert !!!

Andy C

"Andy Cap" wrote in message
o.uk...
Having looked at various replies to the question' How do I work out what
size boiler I require?' it's noticeable that many take the form of 'I
haven't trained as a heating engineer for 30 years to tell you how to do
it for free! Get yourself a book or go to college.' What's wrong with
doing a bit of research when you're going to spend £2000+. If they don't
want to help, why don't they just mind their own business? Oh and is there
anyone who has some pointers? I've tried a 'Whole house calculator' for my
semi and it comes out at 7.7KWs, which seems low but then I'm not an
expert !!!

I agree with them. It would seem that you were asking the questions and
they were minding their own business.

On 07/09/2013 05:13 PM, Mr Pounder wrote:
"Andy Cap" wrote in message
o.uk...
Having looked at various replies to the question' How do I work out what
size boiler I require?' it's noticeable that many take the form of 'I
haven't trained as a heating engineer for 30 years to tell you how to do
it for free! Get yourself a book or go to college.' What's wrong with
doing a bit of research when you're going to spend £2000+. If they don't
want to help, why don't they just mind their own business? Oh and is there
anyone who has some pointers? I've tried a 'Whole house calculator' for my
semi and it comes out at 7.7KWs, which seems low but then I'm not an
expert !!!

I agree with them. It would seem that you were asking the questions and
they were minding their own business.

So if I wanted to know about say Smart TVs and ask on a public forum
about them, it's OK if TV engineers come one and say, get stuffed?
Sorry, I don't get it. If they aren't interest in sharing their
expertise, just don't reply. Is that so difficult?

Andy Cap wrote:
Having looked at various replies to the question' How do I work out what
size boiler I require?' it's noticeable that many take the form of 'I
haven't trained as a heating engineer for 30 years to tell you how to do
it for free! Get yourself a book or go to college.' What's wrong with
doing a bit of research when you're going to spend £2000+. If they don't
want to help, why don't they just mind their own business? Oh and is
there anyone who has some pointers? I've tried a 'Whole house
calculator' for my semi and it comes out at 7.7KWs, which seems low but
then I'm not an expert !!!

Andy C
That does seem very low. Might be worth a double check on your input
figures and units (feet/metres etc?)

I can possibly understand the reaction from pros because there is no
quick answer so some work is needed and there are an abundance of
calculators online for DIY use.

I've done mine recently and got about 18 for a 4bed detached - mixed new
and older construction. I had an old 18kW boiler in there and I knew it
was struggling in the depths of winter so I've just put in a 24kW - time
will tell.
The advice I was given was not to go too big on a just in case basis
otherwise the boiler does not run efficiently.

"Andy Cap" wrote in message
o.uk...
Having looked at various replies to the question' How do I work out what
size boiler I require?' it's noticeable that many take the form of 'I
haven't trained as a heating engineer for 30 years to tell you how to do
it for free! Get yourself a book or go to college.' What's wrong with
doing a bit of research when you're going to spend £2000+. If they don't
want to help, why don't they just mind their own business? Oh and is there
anyone who has some pointers? I've tried a 'Whole house calculator' for my
semi and it comes out at 7.7KWs, which seems low but then I'm not an
expert !!!

Andy C

7.7Kw would be low. Around 20Kw would be more averaqge.

It is not a topic that can be explained in a couple of paragraphs.
So you won't get an anwer here..
Assuming you have basic arithmetic/ science, at least four hours explanation
to cover most aspects.
So the correct answer IS to buy a book or go to college.

On 09/07/13 16:58, Andy Cap wrote:
Having looked at various replies to the question' How do I work out
what size boiler I require?' it's noticeable that many take the form
of 'I haven't trained as a heating engineer for 30 years to tell you
how to do it for free! Get yourself a book or go to college.' What's
wrong with doing a bit of research when you're going to spend £2000+.
If they don't want to help, why don't they just mind their own
business? Oh and is there anyone who has some pointers? I've tried a
'Whole house calculator' for my semi and it comes out at 7.7KWs, which
seems low but then I'm not an expert !!!


that sounds about right. I did one of those (had it done for me) and it
came to 10KW, so in went a 12KW boiler.

NOW it is certainly true it can hold the temperature at 19C when its -5C
outside, that's ALL it can do,. and heaven help me if the temp goes
lower or the house needs further warming.

7.7KW is the steady state heat loss. You should aim at least 50% over
that to ensure the boiler isn't running flat out in winter all the time,
and possibly not at its most efficient if its a modulating boiler. And
you have fast warm up times.

Fortunately I have wood burners in three rooms for when its extra parky.,




Andy C


--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

On Tuesday, July 9, 2013 5:29:37 PM UTC+1, harryagain wrote:
"Andy Cap" wrote in message

So the correct answer IS to buy a book or go to college.

Yes, bit pointless to try to explain it on the internet when there's lots of books in the library and lots of websites explaining it.

Do an Excel spreadsheet.

Heat loss through each structural element is Q, where Q = UAdT

Heat loss due to ventilation is (IIRC) 0.33 x N x Vol x dT.

That's it.

Most heating engineers don't calculate it, they rely on rules of thumb, experienec and oversize everything (you can turn a too-big rad down, but you can't turn a too small rad up).

The other heating engineers can't calculate it.

On 07/09/2013 05:23 PM, Bob Minchin wrote:

The advice I was given was not to go too big on a just in case basis
otherwise the boiler does not run efficiently.

Yes, I've read that too. Looks like I need a book ! I did rate all the
radiators at one point, when I shifted a few around, but I just wanted a
rough idea, which can't be that difficult in a pretty standard,
brick-built semi with cavity insulation and adequate thickness in the
loft. Good job the electricians here aren't so sensitive ! ;-)

Andy C

"Andy Cap" wrote in message
...
On 07/09/2013 05:13 PM, Mr Pounder wrote:
"Andy Cap" wrote in message
o.uk...
Having looked at various replies to the question' How do I work out what
size boiler I require?' it's noticeable that many take the form of 'I
haven't trained as a heating engineer for 30 years to tell you how to do
it for free! Get yourself a book or go to college.' What's wrong with
doing a bit of research when you're going to spend £2000+. If they don't
want to help, why don't they just mind their own business? Oh and is
there
anyone who has some pointers? I've tried a 'Whole house calculator' for
my
semi and it comes out at 7.7KWs, which seems low but then I'm not an
expert !!!

I agree with them. It would seem that you were asking the questions and
they were minding their own business.

So if I wanted to know about say Smart TVs and ask on a public forum about
them, it's OK if TV engineers come one and say, get stuffed? Sorry, I
don't get it. If they aren't interest in sharing their expertise, just
don't reply. Is that so difficult?

You did not say that you asked on a public forum.

On 07/09/2013 05:56 PM, The Natural Philosopher wrote:

'Whole house calculator' for my semi and it comes out at 7.7KWs, which
seems low but then I'm not an expert !!!


that sounds about right. I did one of those (had it done for me) and it
came to 10KW, so in went a 12KW boiler.

NOW it is certainly true it can hold the temperature at 19C when its -5C
outside, that's ALL it can do,. and heaven help me if the temp goes
lower or the house needs further warming.

7.7KW is the steady state heat loss. You should aim at least 50% over
that to ensure the boiler isn't running flat out in winter all the time,
and possibly not at its most efficient if its a modulating boiler. And
you have fast warm up times.

Fortunately I have wood burners in three rooms for when its extra parky.,


Thanks for that, it all makes sense. I've also got a gas fire for a bit
of a boost but I'd prefer not to use it and have the extra extra boiler
capacity. Looks like some sums are necessary. All I want is a ball-park
figure in mind, for when I'm getting quotes from the experts.

"Andy Cap" wrote in message
o.uk...
On 07/09/2013 05:23 PM, Bob Minchin wrote:

The advice I was given was not to go too big on a just in case basis
otherwise the boiler does not run efficiently.

Yes, I've read that too. Looks like I need a book ! I did rate all the
radiators at one point, when I shifted a few around, but I just wanted a
rough idea, which can't be that difficult in a pretty standard,
brick-built semi with cavity insulation and adequate thickness in the
loft. Good job the electricians here aren't so sensitive ! ;-)


Can't you just find out what other people have in similar size/age/level of
insulation properties and be guided by that.

mark

On Tue, 09 Jul 2013 16:58:02 +0100, Andy Cap wrote:

Having looked at various replies to the question' How do I work out what
size boiler I require?' it's noticeable that many take the form of 'I
haven't trained as a heating engineer for 30 years to tell you how to do
it for free! Get yourself a book or go to college.' What's wrong with
doing a bit of research when you're going to spend £2000+. If they don't
want to help, why don't they just mind their own business? Oh and is
there anyone who has some pointers? I've tried a 'Whole house
calculator' for my semi and it comes out at 7.7KWs, which seems low but
then I'm not an expert !!!

Andy C

Just to note that the radiators may not have the biggest demand on the
boiler if it is a combi.

Hot water for two good showers running at once takes a lot more poke than
that required to heat the radiators.

This does of course mean that the boiler is over sized for the radiators
so you lose some efficiency.

I sized the boiler for two showers, and the plumber doing the install said
"I assume you sized the boiler for the showers not the radiators?".

I would assume (although I haven't been down that route) that if you sized
individual rooms for radiators then there should be a straight forward
calculation for how much boiler you need to heat all the radiators.

Cheers

Dave R

On Tuesday 09 July 2013 16:58 Andy Cap wrote in uk.d-i-y:

Having looked at various replies to the question' How do I work out what
size boiler I require?' it's noticeable that many take the form of 'I
haven't trained as a heating engineer for 30 years to tell you how to do
it for free! Get yourself a book or go to college.' What's wrong with
doing a bit of research when you're going to spend £2000+. If they don't
want to help, why don't they just mind their own business? Oh and is
there anyone who has some pointers? I've tried a 'Whole house
calculator' for my semi and it comes out at 7.7KWs, which seems low but
then I'm not an expert !!!

Andy C

Well, where did you post? Trades forums are notorious for having a good few
folk doing an impression of a Klein bottle. The IET forums can be a little
like that and it is noticeable that the more helpful people are either
industrial sparkies or electrical engineers.

Whereas the "WTF do you think you are doing touching electricity - you'll
kill everyone and go to prison!" are more often than not domestic sparkies
who've never done anything else (with no implied disrespect to Adam who is a
fine gentleman and not at all like that).


--
Tim Watts Personal Blog: http://squiddy.blog.dionic.net/

http://www.sensorly.com/ Crowd mapping of 2G/3G/4G mobile signal coverage

Reading this on the web? See:
http://wiki.diyfaq.org.uk/index.php?title=Usenet

On Tue, 09 Jul 2013 17:33:07 +0000, David.WE.Roberts wrote:

Just to note that the radiators may not have the biggest demand on the
boiler if it is a combi.

Hot water for two good showers running at once takes a lot more poke
than that required to heat the radiators.

The combi at our last place was just fine for rads and showers. The
biggest restriction was the speed of filling the bath...

On 07/09/2013 06:32 PM, mark wrote:


Can't you just find out what other people have in similar size/age/level of
insulation properties and be guided by that.

mark


I could. I just thought I'd like some understanding of what might be
installed, but it looks like I'm going to have to go to college ! ;-)

On 09/07/13 18:15, Andy Cap wrote:
On 07/09/2013 05:56 PM, The Natural Philosopher wrote:

'Whole house calculator' for my semi and it comes out at 7.7KWs, which
seems low but then I'm not an expert !!!


that sounds about right. I did one of those (had it done for me) and it
came to 10KW, so in went a 12KW boiler.

NOW it is certainly true it can hold the temperature at 19C when its -5C
outside, that's ALL it can do,. and heaven help me if the temp goes
lower or the house needs further warming.

7.7KW is the steady state heat loss. You should aim at least 50% over
that to ensure the boiler isn't running flat out in winter all the time,
and possibly not at its most efficient if its a modulating boiler. And
you have fast warm up times.

Fortunately I have wood burners in three rooms for when its extra
parky.,


Thanks for that, it all makes sense. I've also got a gas fire for a
bit of a boost but I'd prefer not to use it and have the extra extra
boiler capacity. Looks like some sums are necessary. All I want is a
ball-park figure in mind, for when I'm getting quotes from the experts.

look at where the boiler you intend to buy is at its most efficient, and
size for that output into the winter.

Assuming its a stored hot water thing.

The most fuel is burnt in the months of November December January and
February. That will be over half the total heating bill - maybe 2/3rds.
Forget about summer costs - you want to be as efficient as possible
heating against a 0-5C ambient outside.
If the calcs show 7.7KW look at a boiler than can maintain that
efficiently, but can peak well over 12KW. Thats still not a huge boiler
especially for a combi. But unless it's a one person flat don't install
a combi.

(a Combi +heat bank is just as expensive, if not more so, than a system
boiler + pressurised tank system, and pumps are more expensive than a
water softener to KEEP that pressurised hot water system scale free.
Unless you have intermittent or very low pressure water, soften it, heat
it and store it)

Buying bigger wont be a disaster., Buying to small may well be.

And the more zones you have, the better control over room temps and fuel
burn you have too. If its a total reinstall, think in terms of running 4
core wires everywhere to have motorised valves and stats on almost a
per room basis.

To be able to turn spare rooms down completely is a good thing. And a
sight easier than TRVS on multiple rads.


--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

Tim Watts wrote:
On Tuesday 09 July 2013 16:58 Andy Cap wrote in uk.d-i-y:

Having looked at various replies to the question' How do I work out
what size boiler I require?' it's noticeable that many take the form
of 'I haven't trained as a heating engineer for 30 years to tell you
how to do it for free! Get yourself a book or go to college.' What's
wrong with doing a bit of research when you're going to spend
£2000+. If they don't want to help, why don't they just mind their
own business? Oh and is there anyone who has some pointers? I've
tried a 'Whole house calculator' for my semi and it comes out at
7.7KWs, which seems low but then I'm not an expert !!!

Andy C

Well, where did you post? Trades forums are notorious for having a
good few folk doing an impression of a Klein bottle. The IET forums
can be a little like that and it is noticeable that the more helpful
people are either industrial sparkies or electrical engineers.

Whereas the "WTF do you think you are doing touching electricity -
you'll kill everyone and go to prison!" are more often than not
domestic sparkies who've never done anything else (with no implied
disrespect to Adam who is a fine gentleman and not at all like that).

I have a theory about the difference between industrial and domestic
electricians.

However that theory is not potential.

--
Adam

On Tue, 09 Jul 2013 09:57:27 -0700, Onetap wrote:

On Tuesday, July 9, 2013 5:29:37 PM UTC+1, harryagain wrote:
"Andy Cap" wrote in message

So the correct answer IS to buy a book or go to college.

Yes, bit pointless to try to explain it on the internet when there's
lots of books in the library and lots of websites explaining it.

Do an Excel spreadsheet.

Heat loss through each structural element is Q, where Q = UAdT

Heat loss due to ventilation is (IIRC) 0.33 x N x Vol x dT.

That's it.

Most heating engineers don't calculate it, they rely on rules of thumb,
experienec and oversize everything (you can turn a too-big rad down, but
you can't turn a too small rad up).

The other heating engineers can't calculate it.

When I did my C&G 6084 Energy Efficiency for Domestic Heating back in
2005 (when the Building Regs were changing to mandate mainly High
Efficiency boilers) our instructor said that the Whole House Boiler
Sizing Method[1] had been designed and checked to give an accurate
estimate compared to the elemental method. Still, if one distrusts it's
easy enough to do a simplified elemental for a house. I think I did check
them out side by side a couple of years back and they corresponded
reasonably well.

[1] which I've written up on the wiki

--
John Stumbles

When I was a kid I used to pray every night for a new bicycle. Then I
realised that the Lord doesn't work that way so I stole one and asked Him
to forgive me

On 07/09/2013 07:14 PM, The Natural Philosopher wrote:

The most fuel is burnt in the months of November December January and
February. That will be over half the total heating bill - maybe 2/3rds.
Forget about summer costs - you want to be as efficient as possible
heating against a 0-5C ambient outside.
If the calcs show 7.7KW look at a boiler than can maintain that
efficiently, but can peak well over 12KW. Thats still not a huge boiler
especially for a combi. But unless it's a one person flat don't install
a combi.

(a Combi +heat bank is just as expensive, if not more so, than a system
boiler + pressurised tank system, and pumps are more expensive than a
water softener to KEEP that pressurised hot water system scale free.
Unless you have intermittent or very low pressure water, soften it, heat
it and store it)

Buying bigger wont be a disaster., Buying to small may well be.

And the more zones you have, the better control over room temps and fuel
burn you have too. If its a total reinstall, think in terms of running 4
core wires everywhere to have motorised valves and stats on almost a
per room basis.

To be able to turn spare rooms down completely is a good thing. And a
sight easier than TRVS on multiple rads.



Thanks. I've now done a room by room assessment and the requirement
works out even slightly less. The 15KW Vaillant 415 open-vent boiler I'd
been considering would be more than adequate. I like the simplicity of
system I have and only really want to change the boiler as the
Glowworm's getting a bit long in the tooth now.

Actually though, there are ways to reply which would not put folks backs up
as much as the reply quoted.

The sorry, this is commercially sensitive information which we do not
disclose is much better.
Brian

--
From the Sofa of Brian Gaff Reply address is active
"Mr Pounder" wrote in message
...

"Andy Cap" wrote in message
o.uk...
Having looked at various replies to the question' How do I work out what
size boiler I require?' it's noticeable that many take the form of 'I
haven't trained as a heating engineer for 30 years to tell you how to do
it for free! Get yourself a book or go to college.' What's wrong with
doing a bit of research when you're going to spend £2000+. If they don't
want to help, why don't they just mind their own business? Oh and is
there anyone who has some pointers? I've tried a 'Whole house calculator'
for my semi and it comes out at 7.7KWs, which seems low but then I'm not
an expert !!!

I agree with them. It would seem that you were asking the questions and
they were minding their own business.

In article ,
Andy Cap wrote:


Thanks. I've now done a room by room assessment and the requirement
works out even slightly less. The 15KW Vaillant 415 open-vent boiler I'd
been considering would be more than adequate. I like the simplicity of
system I have and only really want to change the boiler as the
Glowworm's getting a bit long in the tooth now.

What's wrong with an old boiler? Mine dates from 1989 - also Glowworm.

--
From KT24

Using a RISC OS computer running v5.18

On Wed, 10 Jul 2013 08:41:10 +0100, charles wrote:

What's wrong with an old boiler? Mine dates from 1989 - also Glowworm.

It might be rather inefficient, look it up in the SEBUK database
http://www.boilers.org.uk. There could be a 20% or so reduction in
your gas consumption between an old cast iron non condensing boiler
and a modern condensing one. Note condensing does *not* mean combi.

24 years old, spares could well be getting a bit thin on the ground.
Wouldn't be pleasant to have to do a unplanned and rushed boiler swap
in the middle of winter should it breakdown and no spare(s)
available. Better to do a bit of planning and research, then schedule
as swap at your convience (if that is the conclusion) to a boiler
best suited.

--
Cheers
Dave.

On Tuesday, July 9, 2013 7:14:55 PM UTC+1, The Natural Philosopher wrote:
look at where the boiler you intend to buy is at its most efficient, and

size for that output into the winter.

There is, I believe, little difference in the efficiency of a modulating combi boiler at various outputs, providing that the return temperature is low enough to ensure that it is in the condensing region.
A search for efficiency graphs should confirm that.

Multiple boiler installations were usually sequenced so that the minimum number of boilers were firing, i.e., No 2 fired when No 1 was on 100%, No 3 fired when No 2 was on 100%, etc..

I was told (by a manufacturer) that having all the boilers firing at the same part-load would be more efficient.

On 07/10/2013 08:56 AM, Dave Liquorice wrote:

It might be rather inefficient, look it up in the SEBUK database
http://www.boilers.org.uk. There could be a 20% or so reduction in
your gas consumption between an old cast iron non condensing boiler
and a modern condensing one. Note condensing does *not* mean combi.

24 years old, spares could well be getting a bit thin on the ground.
Wouldn't be pleasant to have to do a unplanned and rushed boiler swap
in the middle of winter should it breakdown and no spare(s)
available. Better to do a bit of planning and research, then schedule
as swap at your convience (if that is the conclusion) to a boiler
best suited.


All true. 65% against 90% in my case. I'm really in no haste to dump the
old boiler, because I doubt all the blurb that there's these great
savings to be made, because this old boiler has cost me virtually
nothing over the years and they never factor in replacement costs or
faults, BUT with gas getting ever more expensive, the cost saving *is*
becoming a factor and as you say, getting hold of a gas valve will be
nigh-on impossible. There's the odd second-hand one on Ebay, even one
new one I noticed the other day, but of course that understandably comes
at a premium price.

On 07/09/2013 06:13 PM, Mr Pounder wrote:

So if I wanted to know about say Smart TVs and ask on a public forum about
them, it's OK if TV engineers come one and say, get stuffed? Sorry, I
don't get it. If they aren't interest in sharing their expertise, just
don't reply. Is that so difficult?

You did not say that you asked on a public forum.


I never actually posted anything. I was just looking through previous
questions and the impression I got was the professionals were pretty
off-hand, which I can understand, but if they want a closed-shop then
have a private members group which you have to register for, it's not
difficult. When you hear all the horror stories of people being ripped
off by so-called professionals, it's to be expected that customers will
want to get better informed, before accepting any old quote.

On 10/07/13 08:41, charles wrote:
In article ,
Andy Cap wrote:


Thanks. I've now done a room by room assessment and the requirement
works out even slightly less. The 15KW Vaillant 415 open-vent boiler I'd
been considering would be more than adequate. I like the simplicity of
system I have and only really want to change the boiler as the
Glowworm's getting a bit long in the tooth now.
What's wrong with an old boiler? Mine dates from 1989 - also Glowworm.

700 quid buys a lot of gas...


--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

On Wed, 10 Jul 2013 09:41:58 +0100, The Natural Philosopher wrote:

700 quid buys a lot of gas...

It's only three times the February (mains) gas bill for the 70m2 cottage
we spent the winter in...

On 09/07/2013 16:58, Andy Cap wrote:
Having looked at various replies to the question' How do I work out what
size boiler I require?' it's noticeable that many take the form of 'I
haven't trained as a heating engineer for 30 years to tell you how to do
it for free! Get yourself a book or go to college.' What's wrong with
doing a bit of research when you're going to spend £2000+. If they don't
want to help, why don't they just mind their own business? Oh and is
there anyone who has some pointers? I've tried a 'Whole house
calculator' for my semi and it comes out at 7.7KWs, which seems low but
then I'm not an expert !!!

Why should a professional who has invested time, effort and money in
learning his, or her, trade give you free advice? The rule of thumb is
that free advice is worth what you pay for it. Unless there is some
reasonable prospect of getting some work then you should do your own
homework. There are plenty of websites and library books to help you.

--
Peter Crosland

On Wednesday 10 July 2013 11:55 Peter Crosland wrote in uk.d-i-y:

On 09/07/2013 16:58, Andy Cap wrote:
Having looked at various replies to the question' How do I work out what
size boiler I require?' it's noticeable that many take the form of 'I
haven't trained as a heating engineer for 30 years to tell you how to do
it for free! Get yourself a book or go to college.' What's wrong with
doing a bit of research when you're going to spend £2000+. If they don't
want to help, why don't they just mind their own business? Oh and is
there anyone who has some pointers? I've tried a 'Whole house
calculator' for my semi and it comes out at 7.7KWs, which seems low but
then I'm not an expert !!!

Why should a professional who has invested time, effort and money in
learning his, or her, trade give you free advice? The rule of thumb is
that free advice is worth what you pay for it. Unless there is some
reasonable prospect of getting some work then you should do your own
homework. There are plenty of websites and library books to help you.


Why shouldn't he? A large number of people on uk.d-i-y are professionals in
some area or the other and contribute free advice in their area as well as
others.

Paid advice is Ok but how do you know the person you are paying isn't an
idiot?

I would suggest the only way is by taking a consensus of opinion from people
who have a track record of knowing something.

And besides, it well might come back as a paind job for one of the
professionals.



--
Tim Watts Personal Blog: http://squiddy.blog.dionic.net/

http://www.sensorly.com/ Crowd mapping of 2G/3G/4G mobile signal coverage

Reading this on the web? See:
http://wiki.diyfaq.org.uk/index.php?title=Usenet

On 07/10/2013 11:55 AM, Peter Crosland wrote:
On 09/07/2013 16:58, Andy Cap wrote:
Having looked at various replies to the question' How do I work out what
size boiler I require?' it's noticeable that many take the form of 'I
haven't trained as a heating engineer for 30 years to tell you how to do
it for free! Get yourself a book or go to college.' What's wrong with
doing a bit of research when you're going to spend £2000+. If they don't
want to help, why don't they just mind their own business? Oh and is
there anyone who has some pointers? I've tried a 'Whole house
calculator' for my semi and it comes out at 7.7KWs, which seems low but
then I'm not an expert !!!

Why should a professional who has invested time, effort and money in
learning his, or her, trade give you free advice? The rule of thumb is
that free advice is worth what you pay for it. Unless there is some
reasonable prospect of getting some work then you should do your own
homework. There are plenty of websites and library books to help you.


.... and yet there are several electricians on here who give advice. The
odd question from some stranger in another part of the country is hardly
likely to affect their business. There are loads of boards where you can
get advice on a whole range of stuff. If a guy was actually helpful and
lived in the vicinity, I'd probably offer him the job !

On 09/07/2013 16:58, Andy Cap wrote:
Having looked at various replies to the question' How do I work out what
size boiler I require?' it's noticeable that many take the form of 'I
haven't trained as a heating engineer for 30 years to tell you how to do
it for free! Get yourself a book or go to college.' What's wrong with
doing a bit of research when you're going to spend £2000+. If they don't
want to help, why don't they just mind their own business? Oh and is
there anyone who has some pointers? I've tried a 'Whole house
calculator' for my semi and it comes out at 7.7KWs, which seems low but
then I'm not an expert !!!

Andy C

If you have got a cylinder which has a halfway decent coil (or might in
the future have one), then 7.7kW is unlikely to be sufficient even to
maximise the transfer of that coil. Without any heat going anywhere else.

--
Rod

On Wednesday, July 10, 2013 11:55:01 AM UTC+1, Peter Crosland wrote:

Why should a professional who has invested time, effort and money in
learning his, or her, trade give you free advice? The rule of thumb is
that free advice is worth what you pay for it. Unless there is some
reasonable prospect of getting some work then you should do your own
homework. There are plenty of websites and library books to help you.

That is a reasonable point, but I think it is not the point that the OP was making. He was not complaining that professionals did not respond but that sometimes they did respond only to say they would not help.

Robert

On 10/07/2013 11:55, Peter Crosland wrote:
On 09/07/2013 16:58, Andy Cap wrote:
Having looked at various replies to the question' How do I work
out what size boiler I require?' it's noticeable that many take
the form of 'I haven't trained as a heating engineer for 30 years
to tell you how to do it for free! Get yourself a book or go to
college.' What's wrong with doing a bit of research when you're
going to spend £2000+. If they don't want to help, why don't they
just mind their own business? Oh and is there anyone who has some
pointers? I've tried a 'Whole house calculator' for my semi and it
comes out at 7.7KWs, which seems low but then I'm not an expert
!!!

Why should a professional who has invested time, effort and money in
learning his, or her, trade give you free advice? The rule of thumb
is that free advice is worth what you pay for it. Unless there is
some reasonable prospect of getting some work then you should do
your own homework. There are plenty of websites and library books to
help you.


I use free advice to gauge how competent the professional is as well as
determining his friendly nature. If someone is seemingly obstructive,
that is how I would anticipate him to be after any work when something
has gone wrong.

That is my policy in my own field and I feel it works and gives
confidence to my customers. The alternative is giving the perception of
hiding my ignorance.

On 09/07/2013 18:07, Andy Cap wrote:
On 07/09/2013 05:23 PM, Bob Minchin wrote:

The advice I was given was not to go too big on a just in case basis
otherwise the boiler does not run efficiently.

Yes, I've read that too. Looks like I need a book ! I did rate all the
radiators at one point, when I shifted a few around, but I just wanted a
rough idea, which can't be that difficult in a pretty standard,
brick-built semi with cavity insulation and adequate thickness in the
loft. Good job the electricians here aren't so sensitive ! ;-)

Its not really that difficult with a spreadsheet - and in reality you
will get a much more accurate answer than you will from most "pros"
simply because they don't have the time to do the work required just for
an estimate.

If you start he

http://wiki.diyfaq.org.uk/index.php?title=Heat_loss

It will show you how to work out what the house heat loss is likely to
be. Note that if you are going for a combi boiler, then that becomes a
moot point since you will need to size it for the require hot water
performance.

One you have figures for "worst case" and "normal" you can try and pick
a boiler that will cope with the former, but also modulate down low
enough for the latter.



--
Cheers,

John.

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On 10/07/2013 00:11, John Stumbles wrote:
On Tue, 09 Jul 2013 09:57:27 -0700, Onetap wrote:

On Tuesday, July 9, 2013 5:29:37 PM UTC+1, harryagain wrote:
"Andy Cap" wrote in message

So the correct answer IS to buy a book or go to college.

Yes, bit pointless to try to explain it on the internet when there's
lots of books in the library and lots of websites explaining it.

Do an Excel spreadsheet.

Heat loss through each structural element is Q, where Q = UAdT

Heat loss due to ventilation is (IIRC) 0.33 x N x Vol x dT.

That's it.

Most heating engineers don't calculate it, they rely on rules of thumb,
experienec and oversize everything (you can turn a too-big rad down, but
you can't turn a too small rad up).

The other heating engineers can't calculate it.

When I did my C&G 6084 Energy Efficiency for Domestic Heating back in
2005 (when the Building Regs were changing to mandate mainly High
Efficiency boilers) our instructor said that the Whole House Boiler
Sizing Method[1] had been designed and checked to give an accurate
estimate compared to the elemental method. Still, if one distrusts it's
easy enough to do a simplified elemental for a house. I think I did check
them out side by side a couple of years back and they corresponded
reasonably well.

[1] which I've written up on the wiki

For which, a lickable clink:

http://wiki.diyfaq.org.uk/index.php?...Fboiler_sizing



--
Cheers,

John.

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On 09/07/2013 18:15, Andy Cap wrote:
On 07/09/2013 05:56 PM, The Natural Philosopher wrote:

'Whole house calculator' for my semi and it comes out at 7.7KWs, which
seems low but then I'm not an expert !!!


that sounds about right. I did one of those (had it done for me) and it
came to 10KW, so in went a 12KW boiler.

NOW it is certainly true it can hold the temperature at 19C when its -5C
outside, that's ALL it can do,. and heaven help me if the temp goes
lower or the house needs further warming.

7.7KW is the steady state heat loss. You should aim at least 50% over
that to ensure the boiler isn't running flat out in winter all the time,
and possibly not at its most efficient if its a modulating boiler. And
you have fast warm up times.

Fortunately I have wood burners in three rooms for when its extra parky.,


Thanks for that, it all makes sense. I've also got a gas fire for a bit
of a boost but I'd prefer not to use it and have the extra extra boiler
capacity. Looks like some sums are necessary. All I want is a ball-park
figure in mind, for when I'm getting quotes from the experts.

When I did the numbers on my previous place 3/5 bed semi, it was about
8.6kW IIRC.



--
Cheers,

John.

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On 07/10/2013 02:56 PM, John Rumm wrote:

Thanks for that, it all makes sense. I've also got a gas fire for a bit
of a boost but I'd prefer not to use it and have the extra extra boiler
capacity. Looks like some sums are necessary. All I want is a ball-park
figure in mind, for when I'm getting quotes from the experts.

When I did the numbers on my previous place 3/5 bed semi, it was about
8.6kW IIRC.




I've just finished mine, adding in the water heating and it's come out
at 8.854kw !

On 09/07/2013 18:33, David.WE.Roberts wrote:
On Tue, 09 Jul 2013 16:58:02 +0100, Andy Cap wrote:

Having looked at various replies to the question' How do I work out what
size boiler I require?' it's noticeable that many take the form of 'I
haven't trained as a heating engineer for 30 years to tell you how to do
it for free! Get yourself a book or go to college.' What's wrong with
doing a bit of research when you're going to spend £2000+. If they don't
want to help, why don't they just mind their own business? Oh and is
there anyone who has some pointers? I've tried a 'Whole house
calculator' for my semi and it comes out at 7.7KWs, which seems low but
then I'm not an expert !!!

Andy C

Just to note that the radiators may not have the biggest demand on the
boiler if it is a combi.

Hot water for two good showers running at once takes a lot more poke than
that required to heat the radiators.

This does of course mean that the boiler is over sized for the radiators
so you lose some efficiency.

You tend to find that many which have very high outputs to the DHW have
a lower normal output to the rads anyway. On the 35kW one I used at the
last place its max output to the CH was 24kW, and it modulated down to
about 8kW



--
Cheers,

John.

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\================================================= ================/

On 10/07/2013 12:33, polygonum wrote:
On 09/07/2013 16:58, Andy Cap wrote:
Having looked at various replies to the question' How do I work out what
size boiler I require?' it's noticeable that many take the form of 'I
haven't trained as a heating engineer for 30 years to tell you how to do
it for free! Get yourself a book or go to college.' What's wrong with
doing a bit of research when you're going to spend £2000+. If they don't
want to help, why don't they just mind their own business? Oh and is
there anyone who has some pointers? I've tried a 'Whole house
calculator' for my semi and it comes out at 7.7KWs, which seems low but
then I'm not an expert !!!

Andy C

If you have got a cylinder which has a halfway decent coil (or might in
the future have one), then 7.7kW is unlikely to be sufficient even to
maximise the transfer of that coil. Without any heat going anywhere else.

Indeed - although depending on use patterns that may not actually
matter. Many folks cope with a cylinder heated from either a 3kW
immersion or from a slow indirect coil dumping only 3 - 5kW into it.

(my "fast recovery" unvented cylinder mind you can take heat at 22kW if
the boiler can manage it).


--
Cheers,

John.

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\================================================= ================/

Peter Crosland wrote:
On 09/07/2013 16:58, Andy Cap wrote:
Having looked at various replies to the question' How do I work out
what size boiler I require?' it's noticeable that many take the form
of 'I haven't trained as a heating engineer for 30 years to tell you
how to do it for free! Get yourself a book or go to college.' What's
wrong with doing a bit of research when you're going to spend
£2000+. If they don't want to help, why don't they just mind their
own business? Oh and is there anyone who has some pointers? I've
tried a 'Whole house calculator' for my semi and it comes out at
7.7KWs, which seems low but then I'm not an expert !!!

Why should a professional who has invested time, effort and money in
learning his, or her, trade give you free advice?

They do not have to give free advice.

The easiest way that they can do this is by not posting replies to a forum.

--
Adam