I need to replace my aging Vaillant combi with a new combi boiler. It needs
to serve a three bed house with 9 radiators. I suppose a modern day Vaillant
would probably require minimal re-jigging of pipework but I am just as
interested in efficency/reliability. Many thanks.

"Wainscotting" wrote in message
...
I need to replace my aging Vaillant combi with a new combi boiler. It
needs
to serve a three bed house with 9 radiators. I suppose a modern day
Vaillant
would probably require minimal re-jigging of pipework but I am just as
interested in efficency/reliability. Many thanks.

If you are satisfied with the Vaillants flowrate then replace it for a
condesning version. If you want a higher flowrate, Vaillants are not
brilliant flowrates, then go for a Worcester Bosch Greestar 40kW or an Alpha
CD50. Both of these may be larger than your existing boiler. The Alpha has
a very good flowrate by storing water to assist, inside the combi case.
Look at the web sites and see the sizes.

http://www.alpha-boilers.co.uk/products/CD50.html
http://www.worcester-bosch.co.uk

"IMM" wrote in message
...

"Wainscotting" wrote in message
...
I need to replace my aging Vaillant combi with a new combi boiler. It
needs
to serve a three bed house with 9 radiators. I suppose a modern day
Vaillant
would probably require minimal re-jigging of pipework but I am just as
interested in efficency/reliability. Many thanks.

If you are satisfied with the Vaillants flowrate then replace it for a
condesning version. If you want a higher flowrate, Vaillants are not
brilliant flowrates, then go for a Worcester Bosch Greestar 40kW or an
Alpha
CD50. Both of these may be larger than your existing boiler. The Alpha
has
a very good flowrate by storing water to assist, inside the combi case.
Look at the web sites and see the sizes.

http://www.alpha-boilers.co.uk/products/CD50.html
http://www.worcester-bosch.co.uk



I think my present Vaillant's dhw flow is around 6-7 lpm. Going up to
between 9 and 11 on the Turbomax range would be like heaven. I will have a
look at the links you have provided. Thanks for the info.

"Wainscotting" wrote in message
...

"IMM" wrote in message
...

"Wainscotting" wrote in message
...
I need to replace my aging Vaillant combi with a new combi boiler. It
needs
to serve a three bed house with 9 radiators. I suppose a modern day
Vaillant
would probably require minimal re-jigging of pipework but I am just as
interested in efficency/reliability. Many thanks.

If you are satisfied with the Vaillants flowrate then replace it for a
condesning version. If you want a higher flowrate, Vaillants are not
brilliant flowrates, then go for a Worcester Bosch Greestar 40kW or an
Alpha
CD50. Both of these may be larger than your existing boiler. The Alpha
has
a very good flowrate by storing water to assist, inside the combi case.
Look at the web sites and see the sizes.

http://www.alpha-boilers.co.uk/products/CD50.html
http://www.worcester-bosch.co.uk



I think my present Vaillant's dhw flow is around 6-7 lpm. Going up to
between 9 and 11 on the Turbomax range would be like heaven. I will have a
look at the links you have provided. Thanks for the info.

Greenstar 16 litres/min
CB50 approx 18-19 litres/min.

Using one of these will be heaven

"IMM" wrote in message
...

"Wainscotting" wrote in message
...

"IMM" wrote in message
...

"Wainscotting" wrote in message
...
I need to replace my aging Vaillant combi with a new combi boiler. It
needs
to serve a three bed house with 9 radiators. I suppose a modern day
Vaillant
would probably require minimal re-jigging of pipework but I am just as
interested in efficency/reliability. Many thanks.

If you are satisfied with the Vaillants flowrate then replace it for a
condesning version. If you want a higher flowrate, Vaillants are not
brilliant flowrates, then go for a Worcester Bosch Greestar 40kW or an
Alpha
CD50. Both of these may be larger than your existing boiler. The
Alpha
has
a very good flowrate by storing water to assist, inside the combi case.
Look at the web sites and see the sizes.

http://www.alpha-boilers.co.uk/products/CD50.html
http://www.worcester-bosch.co.uk



I think my present Vaillant's dhw flow is around 6-7 lpm. Going up to
between 9 and 11 on the Turbomax range would be like heaven. I will have
a
look at the links you have provided. Thanks for the info.

Greenstar 16 litres/min
CB50 approx 18-19 litres/min.

Using one of these will be heaven







I read a statement on a website that from 2006 the condensing boilers are
going to be compulsory (I assume for new installations) - is this correct?
Should I be looking at replacing with one of these (as you suggested in
previous message)? I realise that they are supposed to be more energy
efficient and environmentally friendly (apart from the condensate) but is it
true thet they can be more troublesome (whatever that means), have a shorter
life span, only work in condensing mode when the working conditions are
correct and that the system may be to restricted if you have a lot of TRV's?
Just quoting some info. from a website I was looking at. I haven't included
the link as I don't want to get flamed.

On Sun, 16 Jan 2005 23:37:55 -0000, "Wainscotting"
wrote:



I read a statement on a website that from 2006 the condensing boilers are
going to be compulsory (I assume for new installations) - is this correct?

The current intention is April this year (2005).


Should I be looking at replacing with one of these (as you suggested in
previous message)?

It can be a good idea, but check the specifications very carefully
regarding flow rate. Pay particular attention to get the real
numbers for any with internal storage. Seemingly good numbers are
quoted in the marketing blurb, but these are for when the store is
being used. When that runs out - which it will because most are 50
litres or less) the flow rate drops to whatever is implied by the
boiler power output. If the manufacturer hasn't been honest enough
to give the true figure, you can deduce it by comparing with
equivalent power boilers from other manufacturers.

This is not to say that an internal store might not be useful, but do
remember that you can't get a quart out of a pint pot.

All flow rates depend on the ability of the mains to deliver them.

I realise that they are supposed to be more energy
efficient and environmentally friendly (apart from the condensate) but is it
true thet they can be more troublesome (whatever that means), have a shorter
life span, only work in condensing mode when the working conditions are
correct and that the system may be to restricted if you have a lot of TRV's?
Just quoting some info. from a website I was looking at. I haven't included
the link as I don't want to get flamed.


There is a lot of misinformation on this. However:

- early generation UK designed and made condensing boilers did have
reliability problems. Those from Holland and Germany were 3rd
generation at least at that stage and reliable and in those countries
condensing boilers have been used for 20 years.

- nowadays there is not a lot of complexity difference between a
decent conventional boiler and decent condensing boiler. Even the UK
ones have improved considerably - largely because firms have been
acquired by German manufacturers in many cases.

- condensing boilers are more efficient anyway than quite recent
conventional boilers. Efficiency increases at lower temperatures,
and below the temperature at which condensing starts (about 54 degrees
on the return), it increases more rapidly with falling temperature.
It isn't the case that it's necessary for condensing to happen for
there to be a benefit, and neither is it the case that some nirvana is
reached when it happens. It's simply an increase in rate of efficency
with falling temperature.




--

..andy

To email, substitute .nospam with .gl

Andy Hall wrote:

All flow rates depend on the ability of the mains to deliver them.

Could not agree more. My recently installed WB Greenstar 40 plus does
not even need to get its full gear out for the 10l/min that my mains
supplies. My plumber has a go at the stop tap as Yorkshire Water
insists that the mains on street delivers 30l/min. But I really,
really, really should have checked all this before.

Fred

"Fred" wrote in message
...
Andy Hall wrote:

All flow rates depend on the ability of the mains to deliver them.

Could not agree more. My recently installed WB Greenstar 40 plus does
not even need to get its full gear out for the 10l/min that my mains
supplies. My plumber has a go at the stop tap

??

as Yorkshire Water
insists that the mains on street delivers 30l/min. But I really,
really, really should have checked all this before.

You have replaced the stop cock?

"Andy Hall" wrote in message
...
On Sun, 16 Jan 2005 23:37:55 -0000, "Wainscotting"
wrote:



I read a statement on a website that from 2006 the condensing boilers are
going to be compulsory (I assume for new installations) - is this
correct?

The current intention is April this year (2005).


Should I be looking at replacing with one of these (as you suggested in
previous message)?

It can be a good idea, but check the specifications very carefully
regarding flow rate. Pay particular attention to get the real
numbers for any with internal storage. Seemingly good numbers are
quoted in the marketing blurb, but these are for when the store is
being used. When that runs out - which it will because most are 50
litres or less)

Wrong. Most are 50-60. The Alpha is 57 litres. When the hot water is
being drawn off, the boiler is also re-heating the incoming water fast too.
You just don't get only 57 litres into your bath at the high flowrate, you
get far more at the high flowrate. When the store is exhausted about 13-14
litres/min is produced. This will still fill an average modern bath (80-100
litres) pronto. The boiler re-heats the store of water in a matter of a few
minutes.

All flow rates depend on the ability of the mains to deliver them.

There is a lot of misinformation on this. However:

.............and on this ng too.

On Mon, 17 Jan 2005 01:41:44 -0000, "IMM" wrote:


"Andy Hall" wrote in message


It can be a good idea, but check the specifications very carefully
regarding flow rate. Pay particular attention to get the real
numbers for any with internal storage. Seemingly good numbers are
quoted in the marketing blurb, but these are for when the store is
being used. When that runs out - which it will because most are 50
litres or less)

Wrong. Most are 50-60. The Alpha is 57 litres.

That's the conventional CB50. The condensing CD50 is 52 litres.

When the hot water is
being drawn off, the boiler is also re-heating the incoming water fast too.

It can only add in heat at the max output rate of the boiler part.

You just don't get only 57 litres into your bath at the high flowrate, you
get far more at the high flowrate.

You get *some* more. As soon as the initial pre-heated store is
being used, the flow rate will begin to fall because you are taking
energy out faster than it is going in. If the temperature is to
remain constant, then the flow rate will automatically begin to fall.

There is a built in flow regulator, but it is thermostat rather than
sensor controlled, so it would appear that the drop in flow rate will
be sudden.


When the store is exhausted about 13-14
litres/min is produced.

The CB50 produces a max of 28kW to hot water. This equates to 11.5
litres per minute.

The CD50 produces a max of 32kW to hot water. This equates to
13.1lpm, not 13-14.

If you are going to quote specs. do read them properly and try to
stick to one at a time rather than picking the most favourable figures
from different models.


This will still fill an average modern bath (80-100
litres) pronto.

This may be the capacity of your bath, but standard ones require
around 150 litres.


The boiler re-heats the store of water in a matter of a few
minutes.

The manufacturer claims that the CD50 will "fully recharge the store"
in "about 3 minutes" in the marketing blurb. However, in their
specification that time is *only* if the boiler was firing and *only*
to reach 70% of the total.
Through a more realistic 50 degree rise in temperature of the store,
it takes 7 minutes.
The CB50 is even worse at 8 minutes.


There is marketing licence here to put it mildly.

Functionally this thing is like a system boiler with a built in small
storage cylinder and nothing more than that. One might as well have
a separate system boiler and decent sized cylinder and do the job
properly.

It should also be mentioned that this is a pressurised cylinder
product and will have to be professionally installed, tundish fitted
and everything else required for a pressurised storage system.





All flow rates depend on the ability of the mains to deliver them.

There is a lot of misinformation on this. However:

............and on this ng too.

You're telling me......




--

..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...

It can be a good idea, but check the specifications very carefully
regarding flow rate. Pay particular attention to get the real
numbers for any with internal storage. Seemingly good numbers are
quoted in the marketing blurb, but these are for when the store is
being used. When that runs out - which it will because most are 50
litres or less)

Wrong. Most are 50-60. The Alpha is 57 litres.

That's the conventional CB50. The condensing CD50 is 52 litres.

Not less than 50 as you implied

When the hot water is
being drawn off, the boiler is also
re-heating the incoming water fast too.

It can only add in heat at the max
output rate of the boiler part.

I would think so, unless you add your Ronson lighter to assist.

You just don't get only 57 litres into your bath at the high flowrate,
you
get far more at the high flowrate.

You get *some* more. As soon as the initial pre-heated store is
being used, the flow rate will begin to fall because you are taking
energy out faster than it is going in. If the temperature is to
remain constant, then the flow rate will automatically begin to fall.

There is a built in flow regulator, but it is thermostat rather than
sensor controlled, so it would appear that the drop in flow rate will
be sudden.


When the store is exhausted about 13-14
litres/min is produced.

The CB50 produces a max of 28kW to hot water. This equates to 11.5
litres per minute.

The CD50 produces a max of 32kW to hot water. This equates to
13.1lpm, not 13-14.

13.1 is between 13-14. It is isn't it?

If you are going to quote specs.

...and he thinks he can count.

This will still fill an average modern bath (80-100
litres) pronto.

This may be the capacity of your bath,
but standard ones require
around 150 litres.

No. modern standard are 80-100. Get a new bath, a smaller one, you an
environmental disaster area. A one family pollution machine.

The boiler re-heats the store of water in a matter of a few
minutes.

The manufacturer claims that the CD50 will "fully recharge the store"
in "about 3 minutes" in the marketing blurb. However, in their
specification that time is *only* if the boiler was firing and *only*
to reach 70% of the total.
Through a more realistic 50 degree rise in temperature of the store,
it takes 7 minutes.
The CB50 is even worse at 8 minutes.

I would not cal 7 minutes from bad. It is v good. As most of the time it
will not be depleted re-heat is zippo.

Functionally this thing is like a
system boiler with a built in small
storage cylinder and nothing more
than that.

That is all a combi is, with a water section added. Well spotted 10/10.

One might as well have
a separate system boiler
and decent sized cylinder and do the job
properly.

No. A combi then doesn't have the silly cylinders and tanks taking up
space, and NEVER runs out of hot water.

It should also be mentioned that
this is a pressurised cylinder
product and will have to be professionally
installed, tundish fitted and everything
else required for a pressurised storage system.

No tundish as all taken care of inside the casing. I'm not sure if an
unvented combi has to conform to BBA approval.

There is a lot of misinformation on this. However:

............and on this ng too.

You're telling me......

I am.

On Mon, 17 Jan 2005 02:58:22 -0000, "IMM" wrote:

"Andy Hall" wrote in message
.. .


That's the conventional CB50. The condensing CD50 is 52 litres.

Not less than 50 as you implied

Granted, byt many have titchy little tanks and the purpose of those is
quite different.



When the hot water is
being drawn off, the boiler is also
re-heating the incoming water fast too.

It can only add in heat at the max
output rate of the boiler part.

I would think so, unless you add your Ronson lighter to assist.

Don't use them.



You just don't get only 57 litres into your bath at the high flowrate,
you
get far more at the high flowrate.

You get *some* more. As soon as the initial pre-heated store is
being used, the flow rate will begin to fall because you are taking
energy out faster than it is going in. If the temperature is to
remain constant, then the flow rate will automatically begin to fall.

There is a built in flow regulator, but it is thermostat rather than
sensor controlled, so it would appear that the drop in flow rate will
be sudden.


When the store is exhausted about 13-14
litres/min is produced.

The CB50 produces a max of 28kW to hot water. This equates to 11.5
litres per minute.

The CD50 produces a max of 32kW to hot water. This equates to
13.1lpm, not 13-14.

13.1 is between 13-14. It is isn't it?

It's very much closer to 13 than 14, so implying anything approaching
14 is misleading.


If you are going to quote specs.

..and he thinks he can count.

Better than you, it would appear.



This will still fill an average modern bath (80-100
litres) pronto.

This may be the capacity of your bath,
but standard ones require
around 150 litres.

No. modern standard are 80-100. Get a new bath, a smaller one, you an
environmental disaster area. A one family pollution machine.

No they are not. A standard bath requires 150 litres if you want
more than a dribble in the bottom. If you want to use one with your
knees under your chin, that's up to you - unless Archimedes principle
helps you, of course.



The boiler re-heats the store of water in a matter of a few
minutes.

The manufacturer claims that the CD50 will "fully recharge the store"
in "about 3 minutes" in the marketing blurb. However, in their
specification that time is *only* if the boiler was firing and *only*
to reach 70% of the total.
Through a more realistic 50 degree rise in temperature of the store,
it takes 7 minutes.
The CB50 is even worse at 8 minutes.

I would not cal 7 minutes from bad. It is v good. As most of the time it
will not be depleted re-heat is zippo.

It's neither bad nor good, but entirely predictable from the power.
The point is that the marketing blurb, which you are using as
reference, quotes only the best case. It will be depleted
completely when a bath is run, or a decent shower used for a
reasonable time.




Functionally this thing is like a
system boiler with a built in small
storage cylinder and nothing more
than that.

That is all a combi is, with a water section added. Well spotted 10/10.

This isn't even that - it's a system boiler with a cylinder in the
box. It isn't even using the cylinder as a heatbank.



One might as well have
a separate system boiler
and decent sized cylinder and do the job
properly.

No. A combi then doesn't have the silly cylinders and tanks taking up
space, and NEVER runs out of hot water.

Oh good grief. Been drinking the Kool-Aid again? The small cylinder
is inside the box rather than having a proper sized one separately.
Unless you have away of compressing water in the liquid phase, then
the space required for 50 litres of water doesn't change.

"Never runs out of hot water" is a marketing bull**** claim.

I can achieve precisely the same thing with a conventional fast
recovery cylinder under the same flow-reduced operating conditions.




It should also be mentioned that
this is a pressurised cylinder
product and will have to be professionally
installed, tundish fitted and everything
else required for a pressurised storage system.

No tundish as all taken care of inside the casing. I'm not sure if an
unvented combi has to conform to BBA approval.

Go and read the installation book.

A tundish is required and it does fall under building control for
installation (and I don't mean just part L1).



There is a lot of misinformation on this. However:

............and on this ng too.

You're telling me......

I am.


Try reading the specs rather than the glossy, and also look at one
product at a time so that you don't confuse yourself.




--

..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Mon, 17 Jan 2005 02:58:22 -0000, "IMM" wrote:

"Andy Hall" wrote in message
.. .


That's the conventional CB50. The condensing CD50 is 52 litres.

Not less than 50 as you implied

Granted, byt many have titchy little
tanks and the purpose of those is
quite different.

You are on about combi's that have dead leg draw-off lag reduction. Not the
same thing, althiough a largeer stored water combi would do the same thing.

You just don't get only 57 litres into
your bath at the high flowrate,
you get far more at the high flowrate.

You get *some* more.

Tsk, tsk. At 18 litres/min draw-off that will exhaust the store in approx 3
mins, but it is being re-heated at 13 litres/min at the same time. So,
approx an extra 2 mins 18 l/min, which delivers approx 90 litres at a high
flowrate. After the store is exhausted the flow reduced to an infinitely
continuous 13 litres plus for ever. So, an average sized bath can be filled
as quick as a normal cylinder tank setup, when you take into account cold
has to be added too.

There you are.

As soon as the initial pre-heated store is
being used, the flow rate will begin to fall because you are taking
energy out faster than it is going in. If the temperature is to
remain constant, then the flow rate will automatically begin to fall.

There is a built in flow regulator, but it is thermostat rather than
sensor controlled, so it would appear that the drop in flow rate will
be sudden.


When the store is exhausted about 13-14
litres/min is produced.

The CB50 produces a max of 28kW to hot water. This equates to 11.5
litres per minute.

The CD50 produces a max of 32kW to hot water. This equates to
13.1lpm, not 13-14.

13.1 is between 13-14. It is isn't it?

It's very much closer to 13 than 14, so implying anything approaching
14 is misleading.


If you are going to quote specs.

..and he thinks he can count.

Better than you, it would appear.



This will still fill an average modern bath (80-100
litres) pronto.

This may be the capacity of your bath,
but standard ones require
around 150 litres.

No. modern standard are 80-100. Get a new bath, a smaller one, you an
environmental disaster area. A one family pollution machine.

A standard bath requires 150 litres

On what do you base this article of faith?

Functionally this thing is like a
system boiler with a built in small
storage cylinder and nothing more
than that.

That is all a combi is, with a water section added. Well spotted 10/10.

This isn't even that - it's a system
boiler with a cylinder in the
box. It isn't even using the cylinder
as a heatbank.

But it does deliver an average bath at high flowrates and drop to a 2nd
stage flowrate for ever. It never runs out. Got it?

One might as well have
a separate system boiler
and decent sized cylinder and do the job
properly.

No. A combi then doesn't have the silly cylinders and tanks taking up
space, and NEVER runs out of hot water.

"Never runs out of hot water" is
a marketing bull**** claim.

No, an actuallity, unless a) the combi brakes down b) the gas cut off c) the
wateris cut off.

I can achieve precisely the same
thing with a conventional fast
recovery cylinder under the same
flow-reduced operating conditions.

But you have a separate cylinder with all the controls, taking up space,
adding complexity with external zone valves, stats, etc, and looks ugly like
a school boiler house, gives no more than good high flow combi. Appalling.
A high flow combi is a neat all in one case. Fabulous.

The OP wants to know the best combi. A high flow combi will be wonderful
for him. The business. He can also look at the W-B 440 high flow combi too.
Fabulous.

IMM wrote:

No. A combi then doesn't have the silly cylinders and tanks taking up
space, and NEVER runs out of hot water.

This statement (with regard to the Alpha), always strikes me as
disingenious.

You are technically correct that it will not stop producing hot water.
However, as has been pointed out, there will be a time when its flow
rate drops significantly. One must also presume that its temperature
will also drop given that the temperature of the store may be higher
than that which the boiler can susstain for heating cold mains water on
an ongoing basis once the store is exhaused.

So if you start running a bath (especially a normal bath, and not an IMM
special "micro bath"), with 65 degree hot water from the boiler mixed
with (say) 40% cold water, you are going to need to sit there at watch
for the point it runs out of accumulated hot water, otherwise you are
going to return to a bath where the last third has been mixed from 40%
hot water at 40 degrees, mixed with 60% cold! i.e. 'kin freezing.

Similar story in the shower... if you have a fast reacting thermostatic
one you may get away with just a drop in flow rate, but chances are you
will get a least a spell of cold water.

I am not suggesting the Alpha is neccesarily a poor product, it may in
fact be very good and well suited to some installations. So why the
continual overselling of it as a cure to all combi ils?


--
Cheers,

John.

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

On Mon, 17 Jan 2005 10:46:09 -0000, "IMM" wrote:




You just don't get only 57 litres into
your bath at the high flowrate,
you get far more at the high flowrate.

You get *some* more.

Tsk, tsk. At 18 litres/min draw-off that will exhaust the store in approx 3
mins, but it is being re-heated at 13 litres/min at the same time. So,
approx an extra 2 mins 18 l/min, which delivers approx 90 litres at a high
flowrate.

That would assume no internal mixing of the water in the little
cylinder which is not the case, especially since it is so small.

Even the manufacturer doesn't believe that because they put the
thermostat to control flow rate reduction near the bottom.

After the store is exhausted the flow reduced to an infinitely
continuous 13 litres plus for ever.

Plus 0.1. That's it.

So, an average sized bath can be filled
as quick as a normal cylinder tank setup, when you take into account cold
has to be added too.

You have to add cold in either case......


There you are.

This is nonsense.




This will still fill an average modern bath (80-100
litres) pronto.

This may be the capacity of your bath,
but standard ones require
around 150 litres.

No. modern standard are 80-100. Get a new bath, a smaller one, you an
environmental disaster area. A one family pollution machine.

A standard bath requires 150 litres

On what do you base this article of faith?

It's called measurement as opposed to your assertions which certainly
are an article of faith.




Functionally this thing is like a
system boiler with a built in small
storage cylinder and nothing more
than that.

That is all a combi is, with a water section added. Well spotted 10/10.

This isn't even that - it's a system
boiler with a cylinder in the
box. It isn't even using the cylinder
as a heatbank.

But it does deliver an average bath at high flowrates and drop to a 2nd
stage flowrate for ever. It never runs out. Got it?

It delivers part of an average bath at 18lpm and the rest at 13lpm.

The implication of what you say is that a conventional cylinder would
run out. If the flow rate is reduced to a similar level, the water
from that would never run out either. Of course, with a proper sized
cylinder, the issue doesn't arise anyway.



One might as well have
a separate system boiler
and decent sized cylinder and do the job
properly.

No. A combi then doesn't have the silly cylinders and tanks taking up
space, and NEVER runs out of hot water.

"Never runs out of hot water" is
a marketing bull**** claim.

No, an actuallity, unless a) the combi brakes down b) the gas cut off c) the
wateris cut off.

It's a marketing bull**** claim that can be equally applied to any
system where the flow rate is reduced to match power input.

I'm surprised that you fall for this nonsense.

Actually, perhaps I'm not.



I can achieve precisely the same
thing with a conventional fast
recovery cylinder under the same
flow-reduced operating conditions.

But you have a separate cylinder with all the controls, taking up space,
adding complexity with external zone valves, stats, etc, and looks ugly like
a school boiler house, gives no more than good high flow combi. Appalling.

Yours may look like that - mine is pretty neat because I took time and
trouble over it and followed the manufacturer's instructions.

Of course it's totally untrue that an external cylinder does not give
more than the combi you describe. The storage capacity is larger.


A high flow combi is a neat all in one case. Fabulous.

I wouldn't regard a huge, heavy box like this "neat".



The OP wants to know the best combi. A high flow combi will be wonderful
for him. The business.

It may or may not be. I am simply pointing out the potential
shortcomings that of course are not mentioned in the manufacturer's
brochure and have to be deduced from the spec. sheet.

That is not to say that the product may not be suitable, but it is not
necessarily the best thing since Adam had intercourse with Eve.


He can also look at the W-B 440 high flow combi too.
Fabulous.

Does it say so in the brochure? That's good.

This product at least has the store used as a heatbank, although isn't
small.




--

..andy

To email, substitute .nospam with .gl

"John Rumm" wrote in message
...
IMM wrote:

No. A combi then doesn't have
the silly cylinders and tanks taking up
space, and NEVER runs out of hot water.

This statement (with regard to the Alpha),
always strikes me as disingenious.

You are technically correct that it will
not stop producing hot water.
However, as has been pointed out,
there will be a time when its flow
rate drops significantly.

They don't cover the fact that it is a two stage flowrate setup. The pint
is that in norm al one bathroom average house usage it will be turning out
at high flowrate for approx 95% plus of the time it is used. It can also be
used for a two bathroom house, as long as the baths are not filed at the
same time. Fill one and it recovers in minutes and fill the other.

My sister has a full 2 bathroom house and in 20 years, with teenage kids,
has never filled two baths at the same time. The house was fitted with
300-350 litre cylinder that was in reality was overkill storing hot water
that loses heat to standing losses. When it was replaced a smaller quick
recovery cylinder went in. They have never ran out of hot water with the
smaller cylinder.

One must also presume that its temperature
will also drop given that the temperature
of the store may be higher than that which
the boiler can susstain for heating cold mains water on
an ongoing basis once the store is exhausted.

The normal combi situation then, which is not a problem to countless
millions all over the world.

So if you start running a bath (especially a
normal bath, and not an IMM
special "micro bath"),

A modern average bath is now 80-100 litres. That is "not" my assessment.

with 65 degree hot water from the boiler mixed
with (say) 40% cold water, you are going to need to sit there at watch
for the point it runs out of accumulated hot water, otherwise you are
going to return to a bath where the last third has been mixed from 40%
hot water at 40 degrees, mixed with 60% cold! i.e. 'kin freezing.

No you are not.

Similar story in the shower... if you have
a fast reacting thermostatic
one you may get away with just a drop
in flow rate, but chances are you
will get a least a spell of cold water.

Again not the case

I am not suggesting the Alpha is neccesarily
a poor product, it may in
fact be very good and well suited to
some installations. So why the
continual overselling of it as a cure to all combi ils?

It is one of many. There is one poster here who has a hate campaign against
it. It does deliver. In normal everyday usage they do deliver. See, one
happy user:


From: Jape )
Subject: Most powerful combi boiler
Newsgroups: uk.d-i-y
Date: 2005-01-07 01:02:05 PST


I've had fitted an alpha cb50 for exactly those reasons and it fits the bill
perfectly

Shower will take your skin off, and bath fills v quickly with scaldingly hot
water (you can of course turn the thermostat down)

"Andy Hall" wrote in message
...
On Mon, 17 Jan 2005 10:46:09 -0000, "IMM" wrote:




You just don't get only 57 litres into
your bath at the high flowrate,
you get far more at the high flowrate.

You get *some* more.

Tsk, tsk. At 18 litres/min draw-off that will exhaust the store in
approx 3
mins, but it is being re-heated at 13 litres/min at the same time. So,
approx an extra 2 mins 18 l/min, which delivers approx 90 litres at a
high
flowrate.

That would assume no internal mixing of the water in the little
cylinder which is not the case, especially since it is so small.

Even the manufacturer doesn't believe that because they put the
thermostat to control flow rate reduction near the bottom.

After the store is exhausted the flow reduced to an infinitely
continuous 13 litres plus for ever.

Plus 0.1. That's it.

Making things up again.

snip drivel

"Never runs out of hot water" is
a marketing bull**** claim.

No, an actuallity, unless a) the
combi brakes down b) the gas cut off c) the
wateris cut off.

It's a marketing bull**** claim

snip total drivel

Seek professional advise.

IMM wrote:

They don't cover the fact that it is a two stage flowrate setup. The pint
is that in norm al one bathroom average house usage it will be turning out
at high flowrate for approx 95% plus of the time it is used. It can also be

Can't see that... I have never seen one of your 80-100L baths installed
in a real house, hence you will be using both flow rates every time you
fill a bath.

One must also presume that its temperature
will also drop given that the temperature
of the store may be higher than that which
the boiler can susstain for heating cold mains water on
an ongoing basis once the store is exhausted.


The normal combi situation then, which is not a problem to countless
millions all over the world.

Huh? nonsense.

With a normal combi you turn on the tap and water will come out at a
temperature. Come back 20 mins later at it will still be producing water
at the same rate and flow. The Alpha however will not - the flow will
have fallen as will the temperature.

So if you start running a bath (especially a
normal bath, and not an IMM
special "micro bath"),


A modern average bath is now 80-100 litres. That is "not" my assessment.

You keep repeating it and it is still wrong...

I just had a look at the Armitage Shanks site - they have some 20 baths
listed - appart from one one "shower tub" and one extra short 1.5m bath
all of the others held significantly more than 80 - 100L

What sort of average are you computing?

Also when are you going to realise that "most" houses do not have an
"average modern bath" anyway, they have the same bath that was installed
10 to 20 years ago! Not everyone rips and replaces their bathroom every
five years.

More importantly, why when attempting to advise on things like tank size
(be it built into a boiler or not) do you not ask the poster what
capacity bath thay actually have? Rather than making an assumption
designed to reflect your advice in the best possible terms?


with 65 degree hot water from the boiler mixed
with (say) 40% cold water, you are going to need to sit there at watch
for the point it runs out of accumulated hot water, otherwise you are
going to return to a bath where the last third has been mixed from 40%
hot water at 40 degrees, mixed with 60% cold! i.e. 'kin freezing.


No you are not.

I am not what?

Think it through and do the sums...

Similar story in the shower... if you have
a fast reacting thermostatic
one you may get away with just a drop
in flow rate, but chances are you
will get a least a spell of cold water.


Again not the case

The hot drops in flow rate and temperature, in the case of flow rate
this is a step change. Please explain the logic of your statement?



--
Cheers,

John.

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

On Mon, 17 Jan 2005 12:40:39 -0000, "IMM" wrote:




After the store is exhausted the flow reduced to an infinitely
continuous 13 litres plus for ever.

Plus 0.1. That's it.

Making things up again.

snip drivel

Do the sums.


"Never runs out of hot water" is
a marketing bull**** claim.

No, an actuallity, unless a) the
combi brakes down b) the gas cut off c) the
wateris cut off.

It's a marketing bull**** claim

snip total drivel

Seek professional advise.

Hasn't helped you, has it?



--

..andy

To email, substitute .nospam with .gl

"John Rumm" wrote in message
...
IMM wrote:

They don't cover the fact that it is
a two stage flowrate setup. The point
is that in normal one bathroom average
house usage it will be turning out
at high flowrate for approx 95% plus
of the time it is used. It can also be

Can't see that... I have never seen
one of your 80-100L baths installed
in a real house, hence you will be using
both flow rates every time you fill a bath.

I'm sure you never used UFH too, but it is there.

One must also presume that its temperature
will also drop given that the temperature
of the store may be higher than that which
the boiler can susstain for heating cold mains water on
an ongoing basis once the store is exhausted.


The normal combi situation then, which is
not a problem to countless
millions all over the world.

Huh? nonsense.

No it isn't a problem at all. Millions use combi's and love them

So if you start running a bath (especially a
normal bath, and not an IMM
special "micro bath"),


A modern average bath is now 80-100 litres. That is "not" my
assessment.

You keep repeating it and it is still wrong...

It IS correct!!!! Maybe not in your hosue.

I just had a look at the Armitage Shanks site - they have some 20 baths
listed - appart from one one "shower tub" and one extra short 1.5m bath
all of the others held significantly more than 80 - 100L

What sort of average are you computing?

Also when are you going to realise that "most" houses do not have an
"average modern bath" anyway, they have the same bath that was installed
10 to 20 years ago! Not everyone rips and replaces their bathroom every
five years.

I know many who do. Avocado is trendy at the mo.

More importantly, why when attempting
to advise on things like tank size
(be it built into a boiler or not) do you
not ask the poster what
capacity bath thay actually have? Rather
than making an assumption
designed to reflect your advice in the
best possible terms?

An Alpha will fill a 130 litre bath very quick despite dropping to the lower
stage flowrate for the latter part of the fill. This you can't get your
head around. You certainly have no experinece of such a combi either,. So
don't make things up.

snip

IMM wrote:

Can't see that... I have never seen
one of your 80-100L baths installed
in a real house, hence you will be using
both flow rates every time you fill a bath.


I'm sure you never used UFH too, but it is there.

I am not disputing that small baths are made. I pointing out that most
of "us" do not have one installed. If you walk round the sheds or
bathroom showrooms, most of the baths on display are not 80-100L ones
either. Hence this is why we have trouble believing your claims for the
average bath size.

One must also presume that its temperature
will also drop given that the temperature
of the store may be higher than that which
the boiler can susstain for heating cold mains water on
an ongoing basis once the store is exhausted.


The normal combi situation then, which is
not a problem to countless
millions all over the world.

Huh? nonsense.


No it isn't a problem at all. Millions use combi's and love them

I use a combi, and tolerate it - it is a compromise that suited my needs.

However, you are attempting to divert the discussion. We are not talking
about the type of combi that "millions" have installed.

An alpha with combined storage is not a "standard" combi. Its dynamic
performance in the delivery of water is different. With that difference
comes a number of operational procedures that the operator will need to
put in place to get effective use from it. The same is true of a
conventional combi, however the procedures are different.

Vis bath filling procedu

Adequately sized stored system:

Turn on hot and cold, adjust temperature to liking, come back when bath
is full and turn off taps.

Combi:

Turn on hot tap, wait for water to stabilise in temperature. Reduce flow
rate until desired temperature reached, come back when bath full and
turn off tap.

Alpha:

Start as per stored system, wait until hot flow rate reduces, turn
down/off cold tap until desired temperature balance is restored.


For the combi or alpha (and equal) this is not rocket science, and just
requires a bit of training for the user. It may also require some
instruction for guests.

However it is worth pointing out for those looking at a product like the
Alpha, that they will not get the simplicity of operation that a
correctly sized stored water system would provide - it will in fact be
like having a mixture of combi and stored water system, which is not
supprising since it is.

Also when are you going to realise that "most" houses do not have an
"average modern bath" anyway, they have the same bath that was installed
10 to 20 years ago! Not everyone rips and replaces their bathroom every
five years.


I know many who do. Avocado is trendy at the mo.

As a starter perhaps, but we are talking bathroom suites here.

An Alpha will fill a 130 litre bath very quick despite dropping to the lower
stage flowrate for the latter part of the fill.

At last - that is was my point exactly. It will drop off in flow rate,
hence you need to remember to turn down the cold tap when this happens
or you are going to get a tepid bath. Either that, or you need to do
some trial and error to work out a starting temperature for the mix that
is actually too hot, but which will mix down to an acceptable final
temperature when the slug of tepid water is added toward the end.


--
Cheers,

John.

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

The message
from "IMM" contains these words:

Tsk, tsk. At 18 litres/min draw-off that will exhaust the store in approx 3
mins, but it is being re-heated at 13 litres/min at the same time. So,
approx an extra 2 mins 18 l/min, which delivers approx 90 litres at a high
flowrate.

Wow! Wonders will never cease. dIMM attempting some simple arithmetic.
What a pity he got it wrong.

The best case scenario for dIMMs highly questionable example is that the
first 90 litres delivered is made up of the 56l from the store at store
temperature and the remaining 34 litres at whatever temperature rise the
combi can manage at a delivery rate of 18l per minute. In practice the 2
volumes should mix and the temperature in the store drop gradually
rather than suddenly sink which would mean rather less heat getting into
the bath. But then in practice the 18l flow rate couldn't be maintained
as the boiler would start restricting delivery to maintain output
temperature well before the store was exhausted.

--
Roger

"John Rumm" wrote in message
...
IMM wrote:

Can't see that... I have never seen
one of your 80-100L baths installed
in a real house, hence you will be using
both flow rates every time you fill a bath.


I'm sure you never used UFH too, but it is there.

I am not disputing that small baths are made. I pointing out that most
of "us" do not have one installed. If you walk round the sheds or
bathroom showrooms, most of the baths on display are not 80-100L ones
either. Hence this is why we have trouble believing your claims for the
average bath size.

One must also presume that its temperature
will also drop given that the temperature
of the store may be higher than that which
the boiler can susstain for heating cold mains water on
an ongoing basis once the store is exhausted.


The normal combi situation then, which is
not a problem to countless
millions all over the world.

Huh? nonsense.


No it isn't a problem at all. Millions use combi's and love them

I use a combi, and tolerate it - it is a compromise that suited my needs.

However, you are attempting to divert the discussion. We are not talking
about the type of combi that "millions" have installed.

It acts the same way in one of the flowrate stages.

An alpha with combined storage is not
a "standard" combi. Its dynamic
performance in the delivery of water
is different.

Ah, you are getting it.

With that difference
comes a number of operational procedures
that the operator will need to
put in place to get effective use from it.
The same is true of a conventional combi,
however the procedures are different.

Vis bath filling procedu

Adequately sized stored system:

Turn on hot and cold, adjust temperature to liking, come back when bath
is full and turn off taps.

Combi:

Turn on hot tap, wait for water to stabilise in temperature. Reduce flow
rate until desired temperature reached, come back when bath full and
turn off tap.

Alpha:

Start as per stored system, wait until hot flow rate reduces, turn
down/off cold tap until desired temperature balance is restored.


For the combi or alpha (and equal) this is not rocket science, and just
requires a bit of training for the user. It may also require some
instruction for guests.

However it is worth pointing out for those looking at a product like the
Alpha, that they will not get the simplicity of operation that a
correctly sized stored water system would provide - it will in fact be
like having a mixture of combi and stored water system, which is not
supprising since it is.

Not quite. I know of a stored water system that delivers slowly, so the
user acts accordingly in adding cold. I know of a fast one that the user
would need to act differently too.

Also when are you going to realise that "most" houses do not have an
"average modern bath" anyway, they have the same bath that was installed
10 to 20 years ago! Not everyone rips and replaces their bathroom every
five years.


I know many who do. Avocado is trendy at the mo.

As a starter perhaps, but we are talking bathroom suites here.

An Alpha will fill a 130 litre bath very quick despite dropping to the
lower
stage flowrate for the latter part of the fill.

At last - that is was my point exactly.
It will drop off in flow rate,
hence you need to remember to turn
down the cold tap when this happens
or you are going to get a tepid bath.

When I add cold I repeatedly keep testing the temperature of the bath water
with my hand. 99% of people do this. Not a problem.

A combi dropping to a lower flowrate at the very end of a bath fill would
not put people off. The fact that it never runs out of hot water is
appealing to people.

"Roger" wrote in message
k...
The message
from "IMM" contains these words:

Tsk, tsk. At 18 litres/min draw-off that will exhaust the store in
approx 3
mins, but it is being re-heated at 13 litres/min at the same time. So,
approx an extra 2 mins 18 l/min, which delivers approx 90 litres at a
high
flowrate.

Wow! Wonders

snip

Misinformation don't take any notice.

IMM wrote:

When I add cold I repeatedly keep testing the temperature of the bath water
with my hand. 99% of people do this. Not a problem.

So you sit on the edge of the bath the whole time it is filling with you
mit in the water then? No wonder you bought a titchy bath.


--
Cheers,

John.

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

"John Rumm" wrote in message
...
IMM wrote:

When I add cold I repeatedly keep testing the temperature of the bath
water
with my hand. 99% of people do this. Not a problem.

So you sit on the edge of the bath the whole time it is filling with you
mit in the water then? No wonder you bought a titchy bath.

You look in and put your hand in every so often, like the rest of humanity.

The message
from "IMM" contains these words:

snip

The house was fitted with 300-350 litre cylinder

Oh goody, a flexible cylinder. Do tell where I can get one from?

snip

A modern average bath is now 80-100 litres. That is "not" my assessment.

Wrong on every conceivable count.

Average modern baths are getting larger rather than smaller to cater for
Fat *******s like dIMM. Averaged sized people in average sized baths
thus have to use more water than before if they change to an average
modern bath.

80-100 is not an average, it is a range with a mid point (average if you
like) of 90. No one in their right mind would use that little water in
an average sized bath.

No doubt quite true that it is not dIMMS assessment. He just misapplied
figures he didn't understand (so what's new) from some promotional
material.

--
Roger

The message
from "IMM" contains these words:

Tsk, tsk. At 18 litres/min draw-off that will exhaust the store in
approx 3 mins, but it is being re-heated at 13 litres/min at the
same time. So, approx an extra 2 mins 18 l/min, which delivers
approx 90 litres at a high flowrate.

Misinformation don't take any notice.

Yes.

--
Roger

"Roger" wrote in message
k...
The message
from "IMM" contains these words:

Tsk, tsk. At 18 litres/min draw-off that will exhaust the store in
approx 3 mins, but it is being re-heated at 13 litres/min at the
same time. So, approx an extra 2 mins 18 l/min, which delivers
approx 90 litres at a high flowrate.

snip

Misinformation don't take any notice.

"Roger" wrote in message
k...
The message
from "IMM" contains these words:

snip

The house was fitted with 300-350 litre cylinder

Oh goody, a flexible cylinder. Do tell where I can get one from?

snip

Rambling drivel and misinformation

The message
from "IMM" contains these words:

Tsk, tsk. At 18 litres/min draw-off that will exhaust the store in
approx 3 mins, but it is being re-heated at 13 litres/min at the
same time. So, approx an extra 2 mins 18 l/min, which delivers
approx 90 litres at a high flowrate.

snip

Misinformation don't take any notice.

s******

--
Roger

The message
from "IMM" contains these words:

The house was fitted with 300-350 litre cylinder

Oh goody, a flexible cylinder. Do tell where I can get one from?

snip

Rambling drivel and misinformation

dIMM you're a waste of space and you're still wasting bandwidth.

If you have to reply at least try to to give your messages some real
content. Then at least we would have something new to laugh at.

--
Roger

"Roger" wrote in message
k...
The message
from "IMM" contains these words:

The house was fitted with 300-350 litre cylinder

Oh goody, a flexible cylinder. Do tell where I can get one from?

snip

Rambling drivel and misinformation

snip

Rambling drivel and misinformation

On Mon, 17 Jan 2005 17:54:15 GMT, Roger
wrote:

The message
from "IMM" contains these words:

snip

The house was fitted with 300-350 litre cylinder

Oh goody, a flexible cylinder. Do tell where I can get one from?

snip

A modern average bath is now 80-100 litres. That is "not" my assessment.

Wrong on every conceivable count.

Average modern baths are getting larger rather than smaller to cater for
Fat *******s like dIMM. Averaged sized people in average sized baths
thus have to use more water than before if they change to an average
modern bath.

80-100 is not an average, it is a range with a mid point (average if you
like) of 90. No one in their right mind would use that little water in
an average sized bath.

No doubt quite true that it is not dIMMS assessment. He just misapplied
figures he didn't understand (so what's new) from some promotional
material.

So we all want to fill a big bath as quickly as possible. So why store
water then? I have the answer: store gas. We can only get 6 m3 of gas
from the supply per minute - so store it in a big tank in the attic.
Then simply buy as big a combi boiler as you like. 160 kw no problem.

Better still if the manufacturers would make "stackable" combis. You
could arrange them in a matrix. No plumbing required - just push them
together like lego bricks. Bit tired of your old flow rate? Simply add
one more combi to your attic matrix.

Markus

The message
from "IMM" contains these words:

Rambling drivel and misinformation

dIMM that is something that you are very good at, very probably the only
thing you are very good at. But I know and you know and I suspect the
whole world knows by now that if I managed to post a response to one of
your messages that you could refute you would jump in with both feet a
good deal quicker than it takes me to write dIMM you are dIMM by name
and dim by nature.

--
Roger

Roger wrote:

Snip
Average modern baths are getting larger rather than smaller to cater for
Fat *******s like dIMM. Averaged sized people in average sized baths
thus have to use more water than before if they change to an average
modern bath.
Snip

....but surely if the body in the bath is getting bigger AT THE SAME RATE
at the bath is getting larger, then you don't need any more water?

Not actualy true, I suspect, and after 1/2 bottle of wine I'm not going
to try to calculate it!!

Andrew

"Roger" wrote in message
k...
The message
from "IMM" contains these words:

Rambling drivel and misinformation

snip

Rambling drivel and misinformation

"Markus Splenius" wrote in message
...
On Mon, 17 Jan 2005 17:54:15 GMT, Roger
wrote:

The message
from "IMM" contains these words:

snip

The house was fitted with 300-350 litre cylinder

Oh goody, a flexible cylinder. Do tell where I can get one from?

snip

A modern average bath is now 80-100 litres. That is "not" my
assessment.

Wrong on every conceivable count.

Average modern baths are getting larger rather than smaller to cater for
Fat *******s like dIMM. Averaged sized people in average sized baths
thus have to use more water than before if they change to an average
modern bath.

80-100 is not an average, it is a range with a mid point (average if you
like) of 90. No one in their right mind would use that little water in
an average sized bath.

No doubt quite true that it is not dIMMS assessment. He just misapplied
figures he didn't understand (so what's new) from some promotional
material.

So we all want to fill a big bath as quickly as possible. So why store
water then? I have the answer: store gas. We can only get 6 m3 of gas
from the supply per minute - so store it in a big tank in the attic.
Then simply buy as big a combi boiler as you like. 160 kw no problem.

Better still if the manufacturers would make "stackable" combis. You
could arrange them in a matrix. No plumbing required - just push them
together like lego bricks. Bit tired of your old flow rate? Simply add
one more combi to your attic matrix.

Good thinking. Combis about 25-28kW are cheap install two and get 22
litres/min and be within the 62kW a meter will provide. Do a google onn
post poste 2 combi's.
..

"Andrew Chesters" wrote in message
...
Roger wrote:

Snip
Average modern baths are getting larger rather than smaller to cater for
Fat *******s like dIMM. Averaged sized people in average sized baths
thus have to use more water than before if they change to an average
modern bath.
Snip

...but surely if the body in the bath is getting bigger AT THE SAME RATE
at the bath is getting larger, then you don't need any more water?

You are right.

"Roger" wrote in message
k...
The message
from "IMM" contains these words:

Tsk, tsk. At 18 litres/min draw-off that will exhaust the store
in
approx 3 mins, but it is being re-heated at 13 litres/min at the
same time. So, approx an extra 2 mins 18 l/min, which delivers
approx 90 litres at a high flowrate.

snip

Misinformation don't take any notice.

snip

Misinformation don't take any notice.