I know - done to death.. A customer has asked me this question. I have come
up with the following list. Any other thoughts - sensible ones.. no need to
start a debate about the merits - just need a list!

Conventional
Pros
Stored hot water - so water (hot and cold) available if mains supply
fails
Immersion heater backup - hot water if boiler or gas fails
Warm airing cupboard
Cons
Cylinder needs replacement (in this case to comply with building regs)
Storing hot water not as energy efficient
More complex controls
More costly than combi to install


Combi
Pros
High pressure showers without pumps
Only heats hot water you use
No stored water (flooding issue)
Frees cupboard space
Cons
slower bath filling
No warm airing cupboard




---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.698 / Virus Database: 455 - Release Date: 08/06/2004

On Thu, 17 Jun 2004 21:20:48 +0100, "Colin eclipse 2"
wrote:

I know - done to death.. A customer has asked me this question. I have come
up with the following list. Any other thoughts - sensible ones.. no need to
start a debate about the merits - just need a list!

Conventional
Pros
Stored hot water - so water (hot and cold) available if mains supply
fails
Immersion heater backup - hot water if boiler or gas fails
Warm airing cupboard
Cons
Cylinder needs replacement (in this case to comply with building regs)
Storing hot water not as energy efficient
More complex controls
More costly than combi to install


Combi
Pros
High pressure showers without pumps
Only heats hot water you use
No stored water (flooding issue)
Frees cupboard space
Cons
slower bath filling
No warm airing cupboard




---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.698 / Virus Database: 455 - Release Date: 08/06/2004

Conventional wins hands down for me,especially in higher demand
situations.. It seems to me that storing hot water isnt really a big
issue becuase of the turnover rate, i.e not stored for a great length
of time. Well insulated storage vessels and lagging plus possible use
of plastic piping would lower heat losses even more. Compare this to
lower flow rates and wastage of water run off and for a family
home,its conventional all the time,preferably pressurised stored
system.

Just my views for what they are worth.

In an earlier contribution to this discussion,
Colin eclipse 2 wrote:

I know - done to death.. A customer has asked me this question. I
have come up with the following list. Any other thoughts - sensible
ones.. no need to start a debate about the merits - just need a list!

Conventional
Pros
Stored hot water - so water (hot and cold) available if mains
supply fails
Immersion heater backup - hot water if boiler or gas fails
Warm airing cupboard
Cons
Cylinder needs replacement (in this case to comply with
building regs) Storing hot water not as energy efficient
More complex controls
More costly than combi to install


Combi
Pros
High pressure showers without pumps
Only heats hot water you use
No stored water (flooding issue)
Frees cupboard space
Cons
slower bath filling
No warm airing cupboard


I'm not at all sure that a system based on a conventional boiler *does* have
more complex controls. More complex external controls, perhaps - but the
diverter valve in a combi is at least as complex as (say) a mid-position
3-port valve - and seems to be at least as unreliable based on posts in this
NG.

Also on the Cons side for combis, you only get a decent flow of hot water if
you've got sufficient heating power in the boiler *and* a mains cold water
system with sufficient flow capacity. Many houses don't have sufficient cold
flow capacity, and *need* to have stored water systems.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

"Colin eclipse 2" wrote in message
...
I know - done to death.. A customer has asked me this question. I have
come
up with the following list. Any other thoughts - sensible ones.. no need
to
start a debate about the merits - just need a list!

Conventional
Pros
Stored hot water - so water (hot and cold) available if mains supply
fails
Immersion heater backup - hot water if boiler or gas fails
Warm airing cupboard
Cons
Cylinder needs replacement (in this case to comply with building
regs)
Storing hot water not as energy efficient
More complex controls
More costly than combi to install


Combi
Pros
High pressure showers without pumps
Only heats hot water you use
No stored water (flooding issue)
Frees cupboard space
Cons
slower bath filling
No warm airing cupboard


snipped

====================
You can have the best of both worlds if you have the space. Conventional
boiler for CH only and a separate 'Multipoint' for hot water only.

Cic.

In message , Colin eclipse 2
writes
I know - done to death.. A customer has asked me this question. I have come
up with the following list. Any other thoughts - sensible ones.. no need to
start a debate about the merits - just need a list!

Conventional
Pros
Stored hot water - so water (hot and cold) available if mains supply
fails
Immersion heater backup - hot water if boiler or gas fails
Warm airing cupboard
Cons
Cylinder needs replacement (in this case to comply with building regs)
Storing hot water not as energy efficient
More complex controls
More costly than combi to install


Combi
Pros
High pressure showers without pumps
Only heats hot water you use
No stored water (flooding issue)
Frees cupboard space
Cons
slower bath filling
No warm airing cupboard

Combi pcbs are more complex and tend to be a bit more expensive than
conventional boilers

Conventional boilers (correct me if I'm wrong) tend to have an immersion
heater in the HW tank giving DHW backup

--
geoff

In article ,
"Cicero" writes:
====================
You can have the best of both worlds if you have the space. Conventional
boiler for CH only and a separate 'Multipoint' for hot water only.

That's what I've got. It wasn't really by design -- multipoint
blew up a month before I was going to put heating in (see the
FAQ humor section for the details;-) Buying a new one had the
hot water back working in a few hours. Having got a brand new
one, it didn't make sense to rip it out when heating went in,
so boiler just does the heating, and multipoint does hot water.

--
Andrew Gabriel

"Colin eclipse 2" wrote in message
...

I know - done to death.. A customer has asked me this question. I have
come
up with the following list. Any other thoughts - sensible ones.. no need
to
start a debate about the merits - just need a list!

Conventional
Pros
Stored hot water - so water (hot and cold)
available if mains supply fails

-This is so rare an event that is it is not worth taking into consideration.

Immersion heater backup - hot water if boiler or gas fails
Warm airing cupboard

That can be achieved with any heating system, so not so.

Cons
Cylinder needs replacement (in this case to comply with building
regs)

-Cylinders may need replacing every 8 to 10 years in hard water areas.

Storing hot water not as energy efficient
More complex controls
More costly than combi to install

-Very poor shower pressure, having to use an expensive and noisy power
shower pump in some situations.

-The cylinder takes up space.
-Ugly zone valves and pumps around cylinder.

Combi
Pros
High pressure showers without pumps
Only heats hot water you use
No stored water (flooding issue)
Frees cupboard space

-No wating for cylinder to reheat
-HIgh pressure shower after shower can be taken.
-Have a high output, so house warms up faster.
-All the system is inside the one white box.
-No pipes to freeze in the loft

Cons
slower bath filling

High flowrate combi's are available, so not true.

No warm airing cupboard

A small rad can be installed in the airing cupboard taking up no space.

"Set Square" wrote in message
...
In an earlier contribution to this discussion,
Colin eclipse 2 wrote:

I know - done to death.. A customer has asked me this question. I
have come up with the following list. Any other thoughts - sensible
ones.. no need to start a debate about the merits - just need a list!

Conventional
Pros
Stored hot water - so water (hot and cold) available if mains
supply fails
Immersion heater backup - hot water if boiler or gas fails
Warm airing cupboard
Cons
Cylinder needs replacement (in this case to comply with
building regs) Storing hot water not as energy efficient
More complex controls
More costly than combi to install


Combi
Pros
High pressure showers without pumps
Only heats hot water you use
No stored water (flooding issue)
Frees cupboard space
Cons
slower bath filling
No warm airing cupboard


I'm not at all sure that a system based on a conventional boiler *does*
have
more complex controls. More complex external controls, perhaps - but the
diverter valve in a combi is at least as complex as (say) a mid-position
3-port valve - and seems to be at least as unreliable based on posts in
this
NG.

Not so. A few combi;s don't have 3-ways valves in them.

Also on the Cons side for combis, you only get a decent flow of hot water
if
you've got sufficient heating power in the boiler *and* a mains cold water
system with sufficient flow capacity. Many houses don't have sufficient
cold
flow capacity, and *need* to have stored water systems.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

On Fri, 18 Jun 2004 01:20:53 +0100, "IMM" strung
together this:

Not so. A few combi;s don't have 3-ways valves in them.

A few conventional systems don't have 3 way valves either. This is a
'in general' list, not a national statistical survey.
Muppets, I'm just surrounded by ****ing muppets.
--

SJW
A.C.S. Ltd

On Fri, 18 Jun 2004 01:18:47 +0100, "IMM" strung
together this:

Well, he didn't actually, I snipped it all. I was going to point out
the glaring errors, but got bored of typing.
--

SJW
A.C.S. Ltd

On Fri, 18 Jun 2004 01:18:47 +0100, "IMM" wrote:


"Colin eclipse 2" wrote in message
...

I know - done to death.. A customer has asked me this question. I have
come
up with the following list. Any other thoughts - sensible ones.. no need
to
start a debate about the merits - just need a list!

Conventional
Pros
Stored hot water - so water (hot and cold)
available if mains supply fails

-This is so rare an event that is it is not worth taking into consideration.

It happens to me every few months......


Immersion heater backup - hot water if boiler or gas fails
Warm airing cupboard

That can be achieved with any heating system, so not so.


Cons
Cylinder needs replacement (in this case to comply with building
regs)

-Cylinders may need replacing every 8 to 10 years in hard water areas.

One can use a water softener or phosphate doser to avoid this. If
the water is untreated, then heat exchangers on some combis are liable
to scaling.



Storing hot water not as energy efficient
More complex controls
More costly than combi to install

-Very poor shower pressure, having to use an expensive and noisy power
shower pump in some situations.

Flow from a combi can also be poor if it is not a large one.


-The cylinder takes up space.

So does a combi if of high capacity and fitted with some form of
storage.


-Ugly zone valves and pumps around cylinder.

One can have a system boiler.....




Combi
Pros
High pressure showers without pumps
Only heats hot water you use
No stored water (flooding issue)
Frees cupboard space

-No wating for cylinder to reheat

This is irrelevant if the cylinder is adequately sized.

-HIgh pressure shower after shower can be taken.

That depends on the water supply and temperature and rating of the
combi.


-Have a high output, so house warms up faster.

Than what? A system boiler can be equally effective.


-All the system is inside the one white box.

A system boiler can achieve that as well, with the exception of the
cylinder.


-No pipes to freeze in the loft

Irrelevant if they are properly insulated.



Cons
slower bath filling

High flowrate combi's are available, so not true.

We've had that debate and there are demonstrable limitations.



No warm airing cupboard

A small rad can be installed in the airing cupboard taking up no space.


A post suggesting that there are no disadvantages to combis should be
regarded as suspect. Nothing is ever as clear cut.






..andy

To email, substitute .nospam with .gl

"IMM" wrote in message
...

"Colin eclipse 2" wrote in message
...

I know - done to death.. A customer has asked me this question. I have
come
up with the following list. Any other thoughts - sensible ones.. no need
to
start a debate about the merits - just need a list!

Conventional
Pros
Stored hot water - so water (hot and cold)
available if mains supply fails

-This is so rare an event that is it is not worth taking into
consideration.

Immersion heater backup - hot water if boiler or gas fails
Warm airing cupboard

That can be achieved with any heating system, so not so.

Cons
Cylinder needs replacement (in this case to comply with building
regs)

-Cylinders may need replacing every 8 to 10 years in hard water areas.

Storing hot water not as energy efficient
More complex controls
More costly than combi to install

-Very poor shower pressure, having to use an expensive and noisy power
shower pump in some situations.

-The cylinder takes up space.
-Ugly zone valves and pumps around cylinder.

Combi
Pros
High pressure showers without pumps
Only heats hot water you use
No stored water (flooding issue)
Frees cupboard space

-No wating for cylinder to reheat
-HIgh pressure shower after shower can be taken.
-Have a high output, so house warms up faster.
-All the system is inside the one white box.
-No pipes to freeze in the loft

Cons
slower bath filling

High flowrate combi's are available, so not true.

No warm airing cupboard

A small rad can be installed in the airing cupboard taking up no space.

Where do you buy these 'zero volume' radiators? I could do with a few of
them!

"Lurch" wrote in message
...
On Fri, 18 Jun 2004 01:20:53 +0100, "IMM" strung
together this:

Not so. A few combi's don't have
3-ways valves in them.

A few conventional systems don't
have 3 way valves either.

That is true, as it is even worse, they TWO 2-ways valves.

This is a 'in general' list, not a national statistical survey.
Muppets, I'm just surrounded by ****ing muppets.

Then divorce your wife and leave all your family.

"Lurch" wrote in message
...
On Fri, 18 Jun 2004 01:18:47 +0100, "IMM" strung
together this:

Well, he didn't actually, I snipped it all. I was going to point out
the glaring errors, but got bored of typing.

Mr Poll! Bean, now refrain.

"Andy Hall" wrote in message
...
On Fri, 18 Jun 2004 01:18:47 +0100, "IMM" wrote:


"Colin eclipse 2" wrote in message
...

I know - done to death.. A customer has asked me this question. I have
come
up with the following list. Any other thoughts - sensible ones.. no
need
to
start a debate about the merits - just need a list!

Conventional
Pros
Stored hot water - so water (hot and cold)
available if mains supply fails

-This is so rare an event that is it is not worth taking into
consideration.

It happens to me every few months......

Stop making things up.

Immersion heater backup - hot water if boiler or gas fails
Warm airing cupboard

That can be achieved with any heating system, so not so.


Cons
Cylinder needs replacement (in this case to comply with building
regs)

-Cylinders may need replacing every 8 to 10 years in hard water areas.

One can use a water softener or phosphate
doser to avoid this.

Water softener at approx £400 just to buy then the cost of salt too and they
take up space. A de-scaler will only delay the inevitable.

If the water is untreated, then heat exchangers
on some combis are liable
to scaling.

Storing hot water not as energy efficient
More complex controls
More costly than combi to install

-Very poor shower pressure, having to use an expensive and noisy power
shower pump in some situations.

Flow from a combi can also be poor if it is not a large one.

You size accordingly. Many conventional boilers will not fully heat a house
and leave the occupants cold in winter. So, when you fit one you size to
suit. You don't undersize. The same with combi's.

-The cylinder takes up space.

So does a combi if of high capacity
and fitted with some form of
storage.

Such strange logic. A conventional system takes up two lost of space and a
cylinder takes up lots of space unless you go square like an Elson. You
obviously can't figure this out.

-Ugly zone valves and pumps around cylinder.

One can have a system boiler.....

You still need a 3-way vale or TWO 2-way valves.

Combi
Pros
High pressure showers without pumps
Only heats hot water you use
No stored water (flooding issue)
Frees cupboard space

-No wating for cylinder to reheat

This is irrelevant if the cylinder is adequately sized.

You mean oversized, taking up space and more standing heat losses.

-High pressure shower after shower can be taken.

That depends on the water supply
and temperature and rating of the
combi.

You size to suit. Duh...

-Have a high output, so house warms up faster.

Than what? A system boiler can be equally effective.

Combi boiler by their nature have outputs. Conventional boilers are sized
only for a particular house requirements. A combi in 90% of cases will have
spare heating capacity.

-All the system is inside the one white box.

A system boiler can achieve that as
well, with the exception of the
cylinder.

....and the cylinder takes up lots of space and has standing heat losses and
a 3-way va;lve has to be installed as well.

-No pipes to freeze in the loft

Irrelevant if they are properly insulated.

Which is more expense.

Cons
slower bath filling

High flowrate combi's are available, so not true.

We've had that debate and there are demonstrable limitations.

Stop babbling balls..."High flowrate combi's are available".

No warm airing cupboard

A small rad can be installed in the airing cupboard taking up no space.

A post suggesting that there are no
disadvantages to combis should be
regarded as suspect. Nothing is ever as clear cut.

You know nothing of combi's to come out with a ridiculous statement.

"wattie" wrote in message
...

"IMM" wrote in message
...

"Colin eclipse 2" wrote in message
...

I know - done to death.. A customer has asked me this question. I have
come
up with the following list. Any other thoughts - sensible ones.. no
need
to
start a debate about the merits - just need a list!

Conventional
Pros
Stored hot water - so water (hot and cold)
available if mains supply fails

-This is so rare an event that is it is not worth taking into
consideration.

Immersion heater backup - hot water if boiler or gas fails
Warm airing cupboard

That can be achieved with any heating system, so not so.

Cons
Cylinder needs replacement (in this case to comply with building
regs)

-Cylinders may need replacing every 8 to 10 years in hard water areas.

Storing hot water not as energy efficient
More complex controls
More costly than combi to install

-Very poor shower pressure, having to use an expensive and noisy power
shower pump in some situations.

-The cylinder takes up space.
-Ugly zone valves and pumps around cylinder.

Combi
Pros
High pressure showers without pumps
Only heats hot water you use
No stored water (flooding issue)
Frees cupboard space

-No wating for cylinder to reheat
-HIgh pressure shower after shower can be taken.
-Have a high output, so house warms up faster.
-All the system is inside the one white box.
-No pipes to freeze in the loft

Cons
slower bath filling

High flowrate combi's are available, so not true.

No warm airing cupboard

A small rad can be installed in the airing cupboard taking up no space.

Where do you buy these 'zero volume' radiators? I could do with a few of
them!

The ultimate zero volume rads are forced air or underfloor heating. Go for
it.

In article ,
Cicero wrote:
You can have the best of both worlds if you have the space. Conventional
boiler for CH only and a separate 'Multipoint' for hot water only.

Sounds to me like the worst of both worlds.

--
*I'm pretty sure that sex is better than logic, but I can't prove it.

Dave Plowman London SW 12
RIP Acorn

That is true, as it is even worse, they TWO 2-ways valves.

2 port valves are usually much more reliable than 3 port mid position
valves, though.

Christian.

I know - done to death.. A customer has asked me this question. I have
come
up with the following list. Any other thoughts - sensible ones.

As the cylinder needs replacing, you'll also need to explain the relative
benefits of different storage systems.

1. Unvented cylinders.
2. Heatbanks
3. Conventional gravity fed.

Christian.

In article ,
IMM wrote:
Stored hot water - so water (hot and cold)
available if mains supply fails

-This is so rare an event that is it is not worth taking into
consideration.

Really? Happens here in London often enough to be a consideration.

Immersion heater backup - hot water if boiler or gas fails
Warm airing cupboard

That can be achieved with any heating system, so not so.

Perhaps you advocate instant electric water heaters above every basin etc
just in case?

Cons
Cylinder needs replacement (in this case to comply with building
regs)

-Cylinders may need replacing every 8 to 10 years in hard water areas.

Do you source them from China, like your power tools? Good quality ones
won't be effected by hard water - why should they?

Storing hot water not as energy efficient
More complex controls
More costly than combi to install

-Very poor shower pressure, having to use an expensive and noisy power
shower pump in some situations.

As opposed to poor flow from a combi fed one?

-The cylinder takes up space.
-Ugly zone valves and pumps around cylinder.

Some might say them being easily acessible a benefit. Of course they would
be ugly if you fitted them since you're not a plumber...

Combi
Pros
High pressure showers without pumps
Only heats hot water you use
No stored water (flooding issue)
Frees cupboard space

-No wating for cylinder to reheat

Never heard of fast recovery cylinders?

-HIgh pressure shower after shower can be taken.

Becuase they will allow the above...

-Have a high output, so house warms up faster.

I take it you always fit undersized conventional boilers if you have
problems with speed of warmup?

-All the system is inside the one white box.

So it all needs replacing at once with some failures?

-No pipes to freeze in the loft

You've not heard of insulation? Strange.

Cons
slower bath filling

High flowrate combi's are available, so not true.

Please give comparitive costs of uprating incoming water and gas mains,
and the extra cost and size of your little white box that can do all this
to match even a modest storage system in this respect?

No warm airing cupboard

A small rad can be installed in the airing cupboard taking up no space.

Did you get frightened by a storage system as a child, or is installing a
storage system properly just beyond you - the most likely explanation.

--
*The older you get, the better you realize you were.

Dave Plowman London SW 12
RIP Acorn

"Christian McArdle" wrote in message
t...
That is true, as it is even worse, they TWO 2-ways valves.

2 port valves are usually much more reliable than 3 port mid position
valves, though.

And they don't restrict the flow so much.

Rgds

Andy R

"Christian McArdle" wrote in message
t...
I know - done to death.. A customer has asked me this question. I have
come
up with the following list. Any other thoughts - sensible ones.

As the cylinder needs replacing, you'll also need to explain the relative
benefits of different storage systems.

1. Unvented cylinders.
2. Heatbanks
3. Conventional gravity fed.

Correct. A heat bank may the perfect solution to their requirements and
functionality, space and cost.

"Andy R" wrote in message
...

"Christian McArdle" wrote in message
t...
That is true, as it is even worse, they TWO 2-ways valves.

2 port valves are usually much more reliable than 3 port mid position
valves, though.

The so-called reliability is negated by have two of them.

And they don't restrict the flow so much.

Depends on what model you buy. Some restrict it a hell of a lot.

In article ,
Colin eclipse 2 wrote:
I know - done to death.. A customer has asked me this question. I have
come up with the following list. Any other thoughts - sensible ones.. no
need to start a debate about the merits - just need a list!

Only if IMM is on holiday.

--
*A bicycle can't stand alone because it's two tyred.*

Dave Plowman London SW 12
RIP Acorn

Colin eclipse 2 wrote:
I know - done to death.. A customer has asked me this question. I
have come up with the following list. Any other thoughts - sensible
ones.. no need to start a debate about the merits - just need a list!

Conventional
Pros
Stored hot water - so water (hot and cold) available if mains
supply fails
Immersion heater backup - hot water if boiler or gas fails
Warm airing cupboard
Cons
Cylinder needs replacement (in this case to comply with
building regs) Storing hot water not as energy efficient
More complex controls
More costly than combi to install


Combi
Pros
High pressure showers without pumps
Only heats hot water you use
No stored water (flooding issue)
Frees cupboard space
Cons
slower bath filling
No warm airing cupboard


I think combis are a handy compact solution for small flats. Anything
bigger and you're better off with a conventional system, or a thermal store
if you want mains pressure hot water and would like to free up the space in
the roof.

If I had to replace the hot water tank as well as the boiler, I'd be looking
at thermal stores for sure.

Bob

"Bob" wrote in message
...
Colin eclipse 2 wrote:
I know - done to death.. A customer has asked me this question. I
have come up with the following list. Any other thoughts - sensible
ones.. no need to start a debate about the merits - just need a list!

Conventional
Pros
Stored hot water - so water (hot and cold) available if mains
supply fails
Immersion heater backup - hot water if boiler or gas fails
Warm airing cupboard
Cons
Cylinder needs replacement (in this case to comply with
building regs) Storing hot water not as energy efficient
More complex controls
More costly than combi to install


Combi
Pros
High pressure showers without pumps
Only heats hot water you use
No stored water (flooding issue)
Frees cupboard space
Cons
slower bath filling
No warm airing cupboard


I think combis are a handy compact
solution for small flats. Anything
bigger and you're better off with a
conventional system,

Nonsense. Read this thread. There are high flowrate combi's available.
You obviously don't know of these.

if you want mains pressure hot water
and would like to free up the space in
the roof.

Getting better, or put the thermal store in the loft and free up space in
the living areas.

If I had to replace the hot water tank
as well as the boiler, I'd be looking
at thermal stores for sure.

Or a high flowrate combi.

"Christian McArdle" wrote in message
t...
That is true, as it is even worse, they TWO 2-ways valves.

2 port valves are usually much more reliable than 3 port mid position
valves, though.

But then you have TWO to go wrong. 3-way "diverter" valves are essentially
2-ports.

"Lurch" wrote
| Muppets, I'm just surrounded by ****ing muppets.

I didn't know that muppets has the anatomical equipment to, er,

wonders if bendy rubber Kermit has perished in his box in the attic

Owain

On Fri, 18 Jun 2004 09:10:56 +0100, "IMM" strung
together this:

That is true, as it is even worse, they TWO 2-ways valves.

Why is it worse, it makes wiring simpler and gives more flexible
control options.

Then divorce your wife and leave all your family.

I'm not married, but nonetheless, I'll get straight onto the leaving
the family bit. Thanks for the tip.
--

SJW
A.C.S. Ltd

"Lurch" wrote in message
news
On Fri, 18 Jun 2004 09:10:56 +0100, "IMM" strung
together this:

That is true, as it is even worse, they TWO 2-ways valves.

Why is it worse, it makes wiring
simpler and gives more flexible
control options.

Two valve to go wrong. With a combi, there is no wiring.

Then divorce your wife and leave all your family.

I'm not married,

that is understanbdable.

but nonetheless, I'll get straight onto the leaving
the family bit. Thanks for the tip.

In article ,
IMM wrote:
Why is it worse, it makes wiring
simpler and gives more flexible
control options.

Two valve to go wrong. With a combi, there is no wiring.

Well, you apparently don't read this group where internal 'wiring'
problems are a prime cause of boiler failure. Or are you recommending some
non electric boiler with a clockwork timer?

--
*Confession is good for the soul, but bad for your career.

Dave Plowman London SW 12
RIP Acorn

Two valve to go wrong. With a combi, there is no wiring.

Yes, two valves, each costing 30 quid, rather than a 3 port valve modified
just enough by the combi manufacturer for the express purpose of being able
to charge 150 quid for it.

Christian.

Christian McArdle wrote:
Two valve to go wrong. With a combi, there is no wiring.

Yes, two valves, each costing 30 quid, rather than a 3 port valve
modified just enough by the combi manufacturer for the express
purpose of being able to charge 150 quid for it.

Christian.

Make that two _easily accesible_ valves, in most cases.

Apart from leaving myself gasping on the floor due to not turning off the
mains before putting some tape round the connector block, fixing a broken 2
port valve motor was a breeze.

Bob

"Christian McArdle" wrote in message
t...
Two valve to go wrong. With a combi, there is no wiring.

Yes, two valves, each costing 30 quid,

Or £40 or £50.

rather than a 3 port valve modified
just enough by the combi manufacturer for the express purpose of being
able
to charge 150 quid for it.

Combi's use diverter valves and not all are £150. There are combi's that do
not have 3-way valves at all. A conventional system needs valves.

"Bob" wrote in message
...
Christian McArdle wrote:
Two valve to go wrong. With a combi, there is no wiring.

Yes, two valves, each costing 30 quid, rather than a 3 port valve
modified just enough by the combi manufacturer for the express
purpose of being able to charge 150 quid for it.

Christian.

Make that two _easily accesible_ valves, in most cases.

Yes, stuck behind a cylinder.

In article , Imm wrote:
Yes, two valves, each costing 30 quid,

Or £40 or £50.

And £10-12 to fix if it's just the motor - which IME it usually is.

--
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

"Christian McArdle" wrote in
t:


As the cylinder needs replacing, you'll also need to explain the relative
benefits of different storage systems.

1. Unvented cylinders.
2. Heatbanks
3. Conventional gravity fed.

AAAaaaaaarrrrgghhhhhh!

mike

On Fri, 18 Jun 2004 13:44:04 +0100, "IMM" strung
together this:

With a combi, there is no wiring.

I wish I'd have known that when I fitted my combi, I had to wire it
into the mains and fit a temperature controller. I'll not bother with
all that malarkey next time and just connect the 'mains in' terminals
to the room stat connections and hopefully it will self power itself
somehow.
Come to think of it, I'm going to go and disconnect it from the mains
now, it's using electricity up as we speak, if there's no need for it
I'm not paying for it.
--

SJW
A.C.S. Ltd

On Fri, 18 Jun 2004 09:30:25 +0100, "IMM" wrote:


Stored hot water - so water (hot and cold)
available if mains supply fails

-This is so rare an event that is it is not worth taking into
consideration.

It happens to me every few months......

Stop making things up.

Would you like to see the copies of letters to and from the water
supplier? Email me your address and I will be pleased to send you
copies.


-Cylinders may need replacing every 8 to 10 years in hard water areas.

One can use a water softener or phosphate
doser to avoid this.

Water softener at approx £400 just to buy then the cost of salt too and they
take up space. A de-scaler will only delay the inevitable.

Rubbish. The cost of the water softener can easily be offset
against the cost of cylinder replacements. When I replaced mine a
couple of years ago after 20 years, the inside was still pristine.

The cost of salt is more than offset by the savings in detergents and
shampoos. I have posted full details of this previously.


-Very poor shower pressure, having to use an expensive and noisy power
shower pump in some situations.

Flow from a combi can also be poor if it is not a large one.

You size accordingly. Many conventional boilers will not fully heat a house
and leave the occupants cold in winter. So, when you fit one you size to
suit. You don't undersize. The same with combi's.

The issue is the lack of the storage element as you well know,



-The cylinder takes up space.

So does a combi if of high capacity
and fitted with some form of
storage.

Such strange logic. A conventional system takes up two lost of space and a
cylinder takes up lots of space unless you go square like an Elson. You
obviously can't figure this out.

It is a question of location as well as of size.



-Ugly zone valves and pumps around cylinder.

One can have a system boiler.....

You still need a 3-way vale or TWO 2-way valves.

So what.


-No wating for cylinder to reheat

This is irrelevant if the cylinder is adequately sized.

You mean oversized, taking up space and more standing heat losses.

This discussion has also been done to death before. The incremental
space is negligible as is any additional heat loss with a properly
insulated cylinder. I presented calculated numbers on these on
previous occasions.


-High pressure shower after shower can be taken.

That depends on the water supply
and temperature and rating of the
combi.

You size to suit. Duh...

One still cannot get a quart from a pint pot....



-Have a high output, so house warms up faster.

Than what? A system boiler can be equally effective.

Combi boiler by their nature have outputs.

Get away.

Conventional boilers are sized
only for a particular house requirements. A combi in 90% of cases will have
spare heating capacity.

You know full well that that comment is utter crap. System boilers
are widely available with large ranges of modulation.



-All the system is inside the one white box.

A system boiler can achieve that as
well, with the exception of the
cylinder.

...and the cylinder takes up lots of space and has standing heat losses and
a 3-way va;lve has to be installed as well.

Cylinders do not take up any more space than the equivalent storage
capacity built into a combi or CPSU.

This is of course unless you have perfected the technology to compress
liquid phase water.



-No pipes to freeze in the loft

Irrelevant if they are properly insulated.

Which is more expense.

This is rubbish too. The cost is negligible as you often point out
when proposing ridiculously large amounts of loft insulation.




Cons
slower bath filling

High flowrate combi's are available, so not true.

We've had that debate and there are demonstrable limitations.

Stop babbling balls..."High flowrate combi's are available".

This depends upon your definition of "high flow rate". I would not
consider 22lpm at 40 degrees to be high flow rate.



No warm airing cupboard

A small rad can be installed in the airing cupboard taking up no space.

A post suggesting that there are no
disadvantages to combis should be
regarded as suspect. Nothing is ever as clear cut.

You know nothing of combi's to come out with a ridiculous statement.

So you're saying that there are no disadvantages at all? You really
have been drinking the Koolade, haven't you......


..andy

To email, substitute .nospam with .gl

On Thu, 17 Jun 2004 21:20:48 +0100, Colin eclipse 2 wrote:

I know - done to death.. A customer has asked me this question. I have come
up with the following list. Any other thoughts - sensible ones.. no need to
start a debate about the merits - just need a list!

Conventional
Pros
Stored hot water - so water (hot and cold) available if mains supply
fails
Immersion heater backup - hot water if boiler or gas fails
Warm airing cupboard
Cons
Cylinder needs replacement (in this case to comply with building regs)
Storing hot water not as energy efficient
More complex controls
More costly than combi to install


Combi
Pros
High pressure showers without pumps
Only heats hot water you use
No stored water (flooding issue)
Frees cupboard space
Cons
slower bath filling
No warm airing cupboard


The FAQ does contain an extensive and fair spectrum of opinions and views
on this matter. Doubtless such a spectrum will also become apparent in
this thread!

I agree with your list.
I estimate the 'half-life' of the heat in a Grade 3, Part L compliant
cylinder to be around 24 hours. [1]
The major issues in my experience.
a) Customer preference (they may well already be very pro or anti combis)
and it is just not worth reducating them if they have already made up
their mind.
b) Customer preference after being informed about the significant issues.
Backup yes/no. Cylinder space needed. Yes/No. Fast bath filling Yes/No.


[1]The water cools to "off then chill" (say 30C) if we go away for 48 hours with the
HW off. It is, however, really important to pay attention to details like
lagging the draw-off and vent pipes for a metre or so from the cylinder.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at 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