"Andy Hall" wrote in message
...
On Thu, 2 Sep 2004 16:50:29 +0100, "IMM" wrote:



it.

Go away... Cycling? On a heat bank. the compensator says the bottom
section of the store requires 50C, the boiler comes in and makes it 50C
without any boiler cycling. IF the day warms up then it may only want
40C
and when it is below 40C the boiler comes in and reheat that section agin
to
40C.

Note:
1. 50C is a low temperature.
2. It said NO boiler cycling.

This is complete waffle and nonsense.

sniuo

You have not a clue.

Are you now saying that you have
separate flow into the heatbank
at the top for DHW and part way
down for CH,

Yes. I said that many posts ago. You can't read.

or are you suggesting
having cylinder thermostats on the
tank part way down?

No. Each section of the heat abnk has its own controls.

The first of these is pointless because
you might as well do the job
properly and feed the radiators
directly, letting the boiler detect
the temperature and modulating accordingly
into higher efficiency.

You turkey I am not about an expensive modulating boiler - for about the
50th time. You are hard of thinking.

snip

You really do not understand. It is pointless going on with you.

"Andy Hall" wrote in message
...
On Thu, 2 Sep 2004 17:14:28 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Thu, 2 Sep 2004 15:05:07 +0100, "Christian McArdle"

For a DHW system, the objective is to get as much heat as possible in
the shortest time possible into the store. The heatbank does this
well and runs the boiler at full tilt for this short time. That is
certainly more efficient than going via an inadequate coil which
results in slower transfer of heat and cycling. The objective is
different, to CH though.

With CH, the objective is to match the load to the boiler,

Which a weather compensator does with a heat bank between rads and
boiler.
he large volume of water being heated makes it more efficient.



Sigh.

snip

"Andy Hall" wrote in message
...
On Thu, 2 Sep 2004 17:07:18 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Thu, 2 Sep 2004 13:43:17 +0100, "IMM" wrote:


It depends on the type of boiler, and its thermal and control
characteristics. Grunff's application was to absorb a large amount
of heat from an oil boiler when an old coil in cylinder approach, not
surprisingly, couldn't do it.

Can't you read. The oil boiler would be cycling mainly on CH and if a
lousy
cylinder on DHW too.

Perfectly thanks, and at a reading age of greater than 6.

Well it must be 7.

To quote:

"Quite - we have pretty poor mains pressure (just under a bar - the
reservoir is about 12m above the house), and no real space problems.
The reason I put in the thermal store (or heatbank as it seems to be
defined here) was becuse the oil boiler was short cycling, despite all
my attempts to cure it. The thermal store solved this, and provided us
with a nice on demand energy store."

Please explain to me where mains water is used in a CH system other
than to initially pressurise it.

The point is boiler cycling. Not mains pressure water to charge the thing
up.

snip

Not worth it; a confused man.

"Pete C" wrote in message
...
On Thu, 2 Sep 2004 15:05:07 +0100, "Christian McArdle"
wrote:

Hi,

Just a general point, I wonder if it would be better to run the
radiator return through the heatbank lower coil, with a pipestat and
bypass valve across it.

Then as the return temperature from the radiator rises, the valve
would open so excess heat is dumped into the heat bank, reducing the
flow temperature to the boiler to promote efficiency.

If there was a sudden demand on the radiators, the lower temperature
would close the valve so the boiler sees a lower return temperature.

Otherwise the return temperature to the boiler would slowly rise until
the boiler cuts out but the heat stored in the lower part of the heat
bank would help keep the radiators hot and delay the time until the
boiler fires again.

There's probably some more potential in this idea if I could think of
it

The rads directly off the heat bank. The return of the rads runs through a
plate heat exchanger and then back to the heat bank. The return from the
heat bank back to the boiler runs through the plate heat exchanger. The
returning rad water would cool the returning boiler water lower the
temperature. They may be case where this may not occur, but these
occurrences would be few and far between.

On Thu, 2 Sep 2004 19:08:03 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Thu, 2 Sep 2004 16:50:29 +0100, "IMM" wrote:


Are you now saying that you have
separate flow into the heatbank
at the top for DHW and part way
down for CH,

Yes. I said that many posts ago. You can't read.

You were not at all clear. Would you like me to quote the piece in
your post.?



or are you suggesting
having cylinder thermostats on the
tank part way down?

No. Each section of the heat abnk has its own controls.

This is a completely pointless and overcomplicating exercise.



The first of these is pointless because
you might as well do the job
properly and feed the radiators
directly, letting the boiler detect
the temperature and modulating accordingly
into higher efficiency.

You turkey I am not about an expensive modulating boiler - for about the
50th time. You are hard of thinking.

The conclusion was around a modulating boiler several posts before you
introduced this wild goose chase.


..andy

To email, substitute .nospam with .gl

On Thu, 2 Sep 2004 19:18:52 +0100, "IMM" wrote:


"Pete C" wrote in message
.. .
On Thu, 2 Sep 2004 15:05:07 +0100, "Christian McArdle"
wrote:

Hi,

Just a general point, I wonder if it would be better to run the
radiator return through the heatbank lower coil, with a pipestat and
bypass valve across it.

Then as the return temperature from the radiator rises, the valve
would open so excess heat is dumped into the heat bank, reducing the
flow temperature to the boiler to promote efficiency.

If there was a sudden demand on the radiators, the lower temperature
would close the valve so the boiler sees a lower return temperature.

Otherwise the return temperature to the boiler would slowly rise until
the boiler cuts out but the heat stored in the lower part of the heat
bank would help keep the radiators hot and delay the time until the
boiler fires again.

There's probably some more potential in this idea if I could think of
it

The rads directly off the heat bank. The return of the rads runs through a
plate heat exchanger and then back to the heat bank. The return from the
heat bank back to the boiler runs through the plate heat exchanger. The
returning rad water would cool the returning boiler water lower the
temperature. They may be case where this may not occur, but these
occurrences would be few and far between.


This gets more and more stupid. Now you are adding an additional
heat exchanger to the mix.

You've forgotten the plastic pipe under the garage floor to preheat it
all.



..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Thu, 2 Sep 2004 19:08:03 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Thu, 2 Sep 2004 16:50:29 +0100, "IMM" wrote:


Are you now saying that you have
separate flow into the heatbank
at the top for DHW and part way
down for CH,

Yes. I said that many posts ago. You can't read.

You were not at all clear. Would you like me to quote the piece in
your post.?



or are you suggesting
having cylinder thermostats on the
tank part way down?

No. Each section of the heat abnk has its own controls.

This is a completely pointless and overcomplicating exercise.

You clearely do not understand.

The first of these is pointless because
you might as well do the job
properly and feed the radiators
directly, letting the boiler detect
the temperature and modulating accordingly
into higher efficiency.

You clearely do not understand.

You turkey I am not about an expensive modulating boiler - for about the
50th time. You are hard of thinking.

The conclusion was around a modulating boiler several posts before you
introduced this wild goose chase.

No! You were on about a modulating boiler, no one else.

"Andy Hall" wrote in message
...
On Thu, 2 Sep 2004 19:18:52 +0100, "IMM" wrote:


"Pete C" wrote in message
.. .
On Thu, 2 Sep 2004 15:05:07 +0100, "Christian McArdle"
wrote:

Hi,

Just a general point, I wonder if it would be better to run the
radiator return through the heatbank lower coil, with a pipestat and
bypass valve across it.

Then as the return temperature from the radiator rises, the valve
would open so excess heat is dumped into the heat bank, reducing the
flow temperature to the boiler to promote efficiency.

If there was a sudden demand on the radiators, the lower temperature
would close the valve so the boiler sees a lower return temperature.

Otherwise the return temperature to the boiler would slowly rise until
the boiler cuts out but the heat stored in the lower part of the heat
bank would help keep the radiators hot and delay the time until the
boiler fires again.

There's probably some more potential in this idea if I could think of
it

The rads directly off the heat bank. The return of the rads runs through
a
plate heat exchanger and then back to the heat bank. The return from the
heat bank back to the boiler runs through the plate heat exchanger. The
returning rad water would cool the returning boiler water lower the
temperature. They may be case where this may not occur, but these
occurrences would be few and far between.


This gets more and more stupid.
Now you are adding an additional
heat exchanger to the mix.

You clearely do not understand.

You've forgotten the plastic pipe under the garage floor to preheat it
all.

About the only sensible thing you have said.

On Thu, 2 Sep 2004 19:18:52 +0100, "IMM" wrote:

"Pete C" wrote in message
.. .
On Thu, 2 Sep 2004 15:05:07 +0100, "Christian McArdle"
wrote:

Hi,

Just a general point, I wonder if it would be better to run the
radiator return through the heatbank lower coil, with a pipestat and
bypass valve across it.

Then as the return temperature from the radiator rises, the valve
would open so excess heat is dumped into the heat bank, reducing the
flow temperature to the boiler to promote efficiency.

If there was a sudden demand on the radiators, the lower temperature
would close the valve so the boiler sees a lower return temperature.

Otherwise the return temperature to the boiler would slowly rise until
the boiler cuts out but the heat stored in the lower part of the heat
bank would help keep the radiators hot and delay the time until the
boiler fires again.

There's probably some more potential in this idea if I could think of
it

The rads directly off the heat bank. The return of the rads runs through a
plate heat exchanger and then back to the heat bank. The return from the
heat bank back to the boiler runs through the plate heat exchanger. The
returning rad water would cool the returning boiler water lower the
temperature. They may be case where this may not occur, but these
occurrences would be few and far between.

Hi,

I might be getting mixed up with a thermal store. The rads would be
connected directly to the boiler and return through the lower coil of
the cylinder. Basically the lower half of the cylinder would act as a
buffer to reduce cycling when central heating demand is low.

cheers,
Pete.

On Thu, 02 Sep 2004 20:11:07 +0100, Andy Hall
wrote:

This gets more and more stupid. Now you are adding an additional
heat exchanger to the mix.

You've forgotten the plastic pipe under the garage floor to preheat it
all.

LOL!

BTW do all condensing boilers modulate right down, or do some just
have two output levels for DHW or CH?

cheers,
Pete.

"Pete C" wrote in message
...
On Thu, 2 Sep 2004 19:18:52 +0100, "IMM" wrote:

"Pete C" wrote in message
.. .
On Thu, 2 Sep 2004 15:05:07 +0100, "Christian McArdle"
wrote:

Hi,

Just a general point, I wonder if it would be better to run the
radiator return through the heatbank lower coil, with a pipestat and
bypass valve across it.

Then as the return temperature from the radiator rises, the valve
would open so excess heat is dumped into the heat bank, reducing the
flow temperature to the boiler to promote efficiency.

If there was a sudden demand on the radiators, the lower temperature
would close the valve so the boiler sees a lower return temperature.

Otherwise the return temperature to the boiler would slowly rise until
the boiler cuts out but the heat stored in the lower part of the heat
bank would help keep the radiators hot and delay the time until the
boiler fires again.

There's probably some more potential in this idea if I could think of
it

The rads directly off the heat bank. The return of the rads runs through
a
plate heat exchanger and then back to the heat bank. The return from the
heat bank back to the boiler runs through the plate heat exchanger. The
returning rad water would cool the returning boiler water lower the
temperature. They may be case where this may not occur, but these
occurrences would be few and far between.

Hi,

I might be getting mixed up with a
thermal store. The rads would be
connected directly to the boiler
and return through the lower coil of
the cylinder. Basically the lower half
of the cylinder would act as a
buffer to reduce cycling when central
heating demand is low.

So a normal direct rads from boiler and a quick recovery cylinder with an
extra coil at the bottom?

I could improve matters. You are using the bottom half of a cylinder as a
hot water store to prevent boiler cycling. May as well sue a proper heat
bank/thermal store. It will lower the rads return temperature going back to
the boiler, but how much is well ..err...not known. My gut feeling is not
by much. Then you have a stat and a 2-port valve as well and the extra
expense of the coil in the bottom of the cylinder. A plate heat exchanger
is passive and will drop the return temperature quite sharply

"Pete C" wrote in message
...
On Thu, 02 Sep 2004 20:11:07 +0100, Andy Hall
wrote:

This gets more and more stupid. Now you are adding an additional
heat exchanger to the mix.

You've forgotten the plastic pipe under the garage floor to preheat it
all.

LOL!

Either you are laughing at the notions of an amateur, which was good advise
if the mains water pipes are run under a conservatory floor gaining heat
from the sun, or have lost the plot.

BTW do all condensing boilers modulate right down,

None modulate right down to zero. I think the best of them goes to about 5
kW

or do some just
have two output levels for DHW or CH?

None have two outputs as such. One has two boiler run stats to give CH and
DHW, but only when using a priority system; when DHW calls, a diverter valve
diverts all the boilers heat to the cylinder at the temp the DHW stat is set
at.

On Thu, 02 Sep 2004 22:07:24 +0100, Pete C
wrote:

On Thu, 02 Sep 2004 20:11:07 +0100, Andy Hall
wrote:

This gets more and more stupid. Now you are adding an additional
heat exchanger to the mix.

You've forgotten the plastic pipe under the garage floor to preheat it
all.

LOL!

BTW do all condensing boilers modulate right down, or do some just
have two output levels for DHW or CH?

cheers,
Pete.

Most reasonable ones modulate over at least a 3:1 range, some as much
as 8 or 10:1

Some also have different behaviour when they are told (via an
electrical input) that they are driving CH or driving DHW.




..andy

To email, substitute .nospam with .gl

On Thu, 2 Sep 2004 22:19:33 +0100, "IMM" wrote:


"Pete C" wrote in message
.. .
On Thu, 02 Sep 2004 20:11:07 +0100, Andy Hall
wrote:

This gets more and more stupid. Now you are adding an additional
heat exchanger to the mix.

You've forgotten the plastic pipe under the garage floor to preheat it
all.

LOL!

Either you are laughing at the notions of an amateur, which was good advise
if the mains water pipes are run under a conservatory floor gaining heat
from the sun, or have lost the plot.

BTW do all condensing boilers modulate right down,

None modulate right down to zero. I think the best of them goes to about 5
kW

Mine goes down to 3kW.



or do some just
have two output levels for DHW or CH?

None have two outputs as such. One has two boiler run stats to give CH and
DHW, but only when using a priority system; when DHW calls, a diverter valve
diverts all the boilers heat to the cylinder at the temp the DHW stat is set
at.

Or with multiple zone valves and detection as to whether the CH or DHW
is being driven.






..andy

To email, substitute .nospam with .gl

On Thu, 2 Sep 2004 22:12:29 +0100, "IMM" wrote:




I could improve matters.


That's certainly true. Would you like me to tell you how?


..andy

To email, substitute .nospam with .gl

On Thu, 2 Sep 2004 20:52:22 +0100, "IMM" wrote:



You turkey I am not about an expensive modulating boiler - for about the
50th time. You are hard of thinking.

The conclusion was around a modulating boiler several posts before you
introduced this wild goose chase.

No! You were on about a modulating boiler, no one else.



From the OP, (and I quote):


"It looks like the answer is a Worcester Greenstar running vented into
a direct heatbank with a zone valve for the rads and a second zone
valve for the towel rails and airing cupboard rad."


Now let me see.... Hmmm......

Looking at the technical specification of the Worcester Greenstar, it
says that the output to central heating is from 7.4 to 28.8kW.
This sounds awfully like modulating to me......


Who was it that you were saying wasn't reading and paying attention?




..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Thu, 2 Sep 2004 20:52:22 +0100, "IMM" wrote:



You turkey I am not about an expensive modulating boiler - for about
the
50th time. You are hard of thinking.

The conclusion was around a modulating boiler several posts before you
introduced this wild goose chase.

No! You were on about a modulating boiler, no one else.



From the OP, (and I quote):

"It looks like the answer is a Worcester Greenstar running vented into
a direct heatbank with a zone valve for the rads and a second zone
valve for the towel rails and airing cupboard rad."


Now let me see.... Hmmm......

Looking at the technical specification of the Worcester Greenstar, it
says that the output to central heating is from 7.4 to 28.8kW.
This sounds awfully like modulating to me......

Who was it that you were saying wasn't reading and paying attention?

W-B tech people say the "heating" boiler can deliver a constant temp. I know
I have recently put one in and used a late heat exchanger on the red return
to lower the return temp. It works wonderfully.

The ideal heating boiler has some of the flow/ret sensors taken off.

On Thu, 2 Sep 2004 22:40:21 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Thu, 2 Sep 2004 20:52:22 +0100, "IMM" wrote:



You turkey I am not about an expensive modulating boiler - for about
the
50th time. You are hard of thinking.

The conclusion was around a modulating boiler several posts before you
introduced this wild goose chase.

No! You were on about a modulating boiler, no one else.



From the OP, (and I quote):

"It looks like the answer is a Worcester Greenstar running vented into
a direct heatbank with a zone valve for the rads and a second zone
valve for the towel rails and airing cupboard rad."


Now let me see.... Hmmm......

Looking at the technical specification of the Worcester Greenstar, it
says that the output to central heating is from 7.4 to 28.8kW.
This sounds awfully like modulating to me......

Who was it that you were saying wasn't reading and paying attention?

W-B tech people say the "heating" boiler can deliver a constant temp. I know
I have recently put one in and used a late heat exchanger on the red return
to lower the return temp. It works wonderfully.

The ideal heating boiler has some of the flow/ret sensors taken off.



I am sure it *can*, but why screw up a perfectly good and efficient
modulating boiler and wreck its efficiency?

Where did you install this claimed boiler?

I think that you are making this up as you go along......




..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Thu, 2 Sep 2004 22:40:21 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Thu, 2 Sep 2004 20:52:22 +0100, "IMM" wrote:



You turkey I am not about an expensive modulating boiler - for
about
the
50th time. You are hard of thinking.

The conclusion was around a modulating boiler several posts before
you
introduced this wild goose chase.

No! You were on about a modulating boiler, no one else.



From the OP, (and I quote):

"It looks like the answer is a Worcester Greenstar running vented into
a direct heatbank with a zone valve for the rads and a second zone
valve for the towel rails and airing cupboard rad."


Now let me see.... Hmmm......

Looking at the technical specification of the Worcester Greenstar, it
says that the output to central heating is from 7.4 to 28.8kW.
This sounds awfully like modulating to me......

Who was it that you were saying wasn't reading and paying attention?

W-B tech people say the "heating" boiler can deliver a constant temp. I
know
I have recently put one in and used a late heat exchanger on the red
return
to lower the return temp. It works wonderfully.

The ideal heating boiler has some of the flow/ret sensors taken off.

I am sure it *can*, but why screw up a perfectly good and efficient
modulating boiler and wreck its efficiency?

The makers do not seem to think it is inefficient at all.

Where did you install this claimed boiler?

Relatives house, keeping the old boiler as a backup in case the B-W fails.
They just flick a switch to bring in the old clunker and light its pilot.

I think that you are making this up as you go along......

I don't copy you thank you. Keep your dirty habits to yourself.

"IMM" wrote in message
...

"Andy Hall" wrote in message
...
On Thu, 2 Sep 2004 12:26:25 +0100, "IMM" wrote:


"Andy Hall" wrote in message
news
Explain you warped thoughts? Well er don't bother.

There's no warp as far as I am concerned.

As far as you are concerned. Professionals would assess otherwise.

So you wouldn't know, presumably.....

Andy, rub the crayon marks off your screen.

The temperature probe on the
cylinder will provide information about
the temperature of the cylinder.
There is no way for it to know
whether the heat use is for the DHW
or for the radiators.

You are thick.

I'm the one with the engineering degree.

You are still thick.

Degrees are often bestowed upon intelligent idiots.

On Thu, 2 Sep 2004 23:01:54 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Thu, 2 Sep 2004 22:40:21 +0100, "IMM" wrote:

Now leet me see.... Hmmm......

Looking at the technical specification of the Worcester Greenstar, it
says that the output to central heating is from 7.4 to 28.8kW.
This sounds awfully like modulating to me......

Who was it that you were saying wasn't reading and paying attention?

W-B tech people say the "heating" boiler can deliver a constant temp. I
know
I have recently put one in and used a late heat exchanger on the red
return
to lower the return temp. It works wonderfully.

The ideal heating boiler has some of the flow/ret sensors taken off.

I am sure it *can*, but why screw up a perfectly good and efficient
modulating boiler and wreck its efficiency?

The makers do not seem to think it is inefficient at all.

Wowee. Well they're not going to say "By the way, John, this is not
the most efficient way to run a condensing boiler", are they?

After all, they still sell conventional boilers and are quite pleased
with themselves about that.

The fact is that more efficient operation by far happens at lower F&R
temperatures.



Where did you install this claimed boiler?

Relatives house, keeping the old boiler as a backup in case the B-W fails.

A win,win situation, I'm sure.

They just flick a switch to bring in the old clunker and light its pilot.

How do you react to having your pilot lit?

..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Thu, 2 Sep 2004 23:01:54 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Thu, 2 Sep 2004 22:40:21 +0100, "IMM" wrote:

Now leet me see.... Hmmm......

Looking at the technical specification of the Worcester Greenstar,
it
says that the output to central heating is from 7.4 to 28.8kW.
This sounds awfully like modulating to me......

Who was it that you were saying wasn't reading and paying attention?

W-B tech people say the "heating" boiler can deliver a constant temp.
I
know
I have recently put one in and used a late heat exchanger on the red
return
to lower the return temp. It works wonderfully.

The ideal heating boiler has some of the flow/ret sensors taken off.

I am sure it *can*, but why screw up a perfectly good and efficient
modulating boiler and wreck its efficiency?

The makers do not seem to think it is inefficient at all.

Wowee. Well they're not going to say "By the way, John, this is not
the most efficient way to run a condensing boiler", are they?

You are confused in many respects. Very confused. All of a sudden he is a
boiler designer.

After all, they still sell conventional
boilers and are quite pleased
with themselves about that.

The fact is that more efficient operation
by far happens at lower F&R
temperatures.

And that can be achieved by various methods.

Where did you install this claimed boiler?

Relatives house, keeping the old boiler as a backup in case the B-W
fails.

A win,win situation, I'm sure.

Must be.

"smiffy" wrote in message
...

"IMM" wrote in message
...

"Andy Hall" wrote in message
...
On Thu, 2 Sep 2004 12:26:25 +0100, "IMM" wrote:


"Andy Hall" wrote in message
news
Explain you warped thoughts? Well er don't bother.

There's no warp as far as I am concerned.

As far as you are concerned. Professionals would assess otherwise.

So you wouldn't know, presumably.....

Andy, rub the crayon marks off your screen.

The temperature probe on the
cylinder will provide information about
the temperature of the cylinder.
There is no way for it to know
whether the heat use is for the DHW
or for the radiators.

You are thick.

I'm the one with the engineering degree.

You are still thick.

Degrees are often bestowed upon intelligent idiots.

This is a classic case.

On Thu, 2 Sep 2004 23:30:19 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Thu, 2 Sep 2004 23:01:54 +0100, "IMM" wrote:



The ideal heating boiler has some of the flow/ret sensors taken off.

I am sure it *can*, but why screw up a perfectly good and efficient
modulating boiler and wreck its efficiency?

The makers do not seem to think it is inefficient at all.

Wowee. Well they're not going to say "By the way, John, this is not
the most efficient way to run a condensing boiler", are they?

You are confused in many respects. Very confused. All of a sudden he is a
boiler designer.

The principles are clearly explained in the link that I posted earlier
and are quite straightforward for anybody who understands the
principles of latent heat and a few other simple principles of
physics.

There is very little individual design left in condensing boilers on
the market today with all having quoted laboratory efficiency figures
within a percent or two at the most.

The question then becomes one of using the instrumentation of the
boiler effectively in order to maximise its efficiency by matching to
the load.



After all, they still sell conventional
boilers and are quite pleased
with themselves about that.

The fact is that more efficient operation
by far happens at lower F&R
temperatures.

And that can be achieved by various methods.

The simple and most effective one being to directly couple the boiler
to the heating circuit and let it use its internal control systems
properly.

The only way to match this with external systems and controls is by
having a boiler which can take an analogue or PWM signal to modulate
it and to then use more sophisticated external controls with more
analogue or analogue equivalent sensors.

Adding on pieces with on/off controls such as thermostats, weather
compensators with on/off outputs and the like is not going to do as
good a job as the analogue sensors that the boiler manufacturers use
in their products. The best that they can do is a very crude
simulation of an analogue control system, and that is simply not going
to match up.



..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Wed, 1 Sep 2004 13:54:06 +0100, "IMM" wrote:


"Dave" wrote in message
...

I think a couple of people installed Heat Banks last year - what are
your
views having run them for a while?

Can anyone explain the relative merits
of heating the heatbank directly or
indirectly?

When direct "all" the boilers heat goes into the store. When indirect
you
are relying on the efficiency of the coil.

Why would I choose to make the primary
circuit pressurised or vented?

In theory pressurised has little advantages over vented when using a heat
bank, as long as the system is fitted correctly and inhibitor is used and
replaced every 3-4 years. Pressurised does away with the F&E tank, in a
heat
bank this can be integrated with the store.


Also making the primary pressurised with a direct heatbank (i.e. the
bulk contents of the cylinder are pressurised) means that for Building
Regulations section G purposes it counts as a sealed storage system
and must therefore be installed by a certified installer.

Not according to RCM:
"Thermaflow is a primary water thermal storage unit that supplies mains
pressure domestic hot water at good flow rates in accordance with the
requirements of BS 6700.
NHBC and the Water Heater Manufacturers Association Specification.
The thermaflow system facilities easy installation without the requirements
for building control or BBA approval and is readily incorporated into
traditional or modern central heating systems. NO MORE NEED FOR COLD WATER
STORAGE TANK IN YOUR ATTIC."
http://www.rcmgroup.co.uk/files/ThermaflowINST.pdf

This is a "pressurised" thermal store to assist combi's and give higher
flowrates.

"Andy Hall" wrote in message
...
On Thu, 2 Sep 2004 23:30:19 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Thu, 2 Sep 2004 23:01:54 +0100, "IMM" wrote:



The ideal heating boiler has some of the flow/ret sensors taken
off.

I am sure it *can*, but why screw up a perfectly good and efficient
modulating boiler and wreck its efficiency?

The makers do not seem to think it is inefficient at all.

Wowee. Well they're not going to say "By the way, John, this is not
the most efficient way to run a condensing boiler", are they?

You are confused in many respects. Very confused. All of a sudden he is
a
boiler designer.

The principles are clearly explained in the link that I posted earlier
and are quite straightforward for anybody who understands the
principles of latent heat and a few other simple principles of
physics.

There is very little individual design left in condensing boilers on
the market today with all having quoted laboratory efficiency figures
within a percent or two at the most.

The question then becomes one of using the instrumentation of the
boiler effectively in order to maximise its efficiency by matching to
the load.

So does that web site mean the W-B boiler is pants?

After all, they still sell conventional
boilers and are quite pleased
with themselves about that.

The fact is that more efficient operation
by far happens at lower F&R
temperatures.

And that can be achieved by various methods.

The simple and most effective
one being to directly couple the boiler
to the heating circuit and let it use its
internal control systems
properly.

It isn't.

snip confused stuff

On Fri, 3 Sep 2004 00:12:43 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Wed, 1 Sep 2004 13:54:06 +0100, "IMM" wrote:



Also making the primary pressurised with a direct heatbank (i.e. the
bulk contents of the cylinder are pressurised) means that for Building
Regulations section G purposes it counts as a sealed storage system
and must therefore be installed by a certified installer.

Not according to RCM:
"Thermaflow is a primary water thermal storage unit that supplies mains
pressure domestic hot water at good flow rates in accordance with the
requirements of BS 6700.
NHBC and the Water Heater Manufacturers Association Specification.
The thermaflow system facilities easy installation without the requirements
for building control or BBA approval and is readily incorporated into
traditional or modern central heating systems. NO MORE NEED FOR COLD WATER
STORAGE TANK IN YOUR ATTIC."
http://www.rcmgroup.co.uk/files/ThermaflowINST.pdf

This is a "pressurised" thermal store to assist combi's and give higher
flowrates.


Well..... your friend Rocky seems to disagree.

From Part G3 of the Approved Documents to the Building Regulations, an
Unvented Hot Water Storage System means an unvented vessel for either

a) storing domestic hot water for subsequent use, or

b) heating domestic water that passes through an integral pipe or coil


The Thermaflow seems to definitely be b)


..andy

To email, substitute .nospam with .gl

On Fri, 3 Sep 2004 00:24:58 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Thu, 2 Sep 2004 23:30:19 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Thu, 2 Sep 2004 23:01:54 +0100, "IMM" wrote:



The ideal heating boiler has some of the flow/ret sensors taken
off.

I am sure it *can*, but why screw up a perfectly good and efficient
modulating boiler and wreck its efficiency?

The makers do not seem to think it is inefficient at all.

Wowee. Well they're not going to say "By the way, John, this is not
the most efficient way to run a condensing boiler", are they?

You are confused in many respects. Very confused. All of a sudden he is
a
boiler designer.

The principles are clearly explained in the link that I posted earlier
and are quite straightforward for anybody who understands the
principles of latent heat and a few other simple principles of
physics.

There is very little individual design left in condensing boilers on
the market today with all having quoted laboratory efficiency figures
within a percent or two at the most.

The question then becomes one of using the instrumentation of the
boiler effectively in order to maximise its efficiency by matching to
the load.

So does that web site mean the W-B boiler is pants?

Go and read it and decide for yourself.

Generically, a condensing boiler will have greater efficiency when run
at lower temperatures and when the rate of heat production matches the
characteristics of the load.

This is not a surprising result because the former is influenced by
the degree to which latent heat can be exploited and the latter
impacts on this and cycling. Having an effective control loop in
place with the boiler able to sense the operating load properly is the
best way to achieve that.




After all, they still sell conventional
boilers and are quite pleased
with themselves about that.

The fact is that more efficient operation
by far happens at lower F&R
temperatures.

And that can be achieved by various methods.

The simple and most effective
one being to directly couple the boiler
to the heating circuit and let it use its
internal control systems
properly.

It isn't.

Actually it is.

Within the context of having the boiler in direct control of its load
with its internal control system and using analogue sensing vs. having
simple external sources turn it on and off, the former is clearly
going to be the most effective and efficient.

Only the introduction of more sophisticated external controllers with
either PWM or analogue control of boiler modulation would improve on
the boiler internal control system in terms of oprating the boiler in
its most effcient range.

For a normal domestic application this would be costly.



..andy

To email, substitute .nospam with .gl

On Thu, 02 Sep 2004 22:25:46 +0100, Andy Hall
wrote:

On Thu, 2 Sep 2004 22:19:33 +0100, "IMM" wrote:

None modulate right down to zero. I think the best of them goes to about 5
kW

Mine goes down to 3kW.

Oh well, I suppose it comes down to the cost of an extra heat
exchanger and pump vs the money saved by a cheaper boiler and reduced
boiler cycling.

I'd expect the heat loss when cycling is due to losses from the
boiler's heat exchanger when the water isn't being heated, and
shouldn't be too bad with a modulating condensing boiler using an
aluminium exhanger.

cheers,
Pete.

On Fri, 03 Sep 2004 11:03:16 +0100, Pete C
wrote:

On Thu, 02 Sep 2004 22:25:46 +0100, Andy Hall
wrote:

On Thu, 2 Sep 2004 22:19:33 +0100, "IMM" wrote:

None modulate right down to zero. I think the best of them goes to about 5
kW

Mine goes down to 3kW.

Oh well, I suppose it comes down to the cost of an extra heat
exchanger and pump vs the money saved by a cheaper boiler and reduced
boiler cycling.

I'd expect the heat loss when cycling is due to losses from the
boiler's heat exchanger when the water isn't being heated, and
shouldn't be too bad with a modulating condensing boiler using an
aluminium exhanger.

cheers,
Pete.



This was my point. You don't need an extra heat exchanger or pump.

You simply connect the modulating boiler via either a diverter valve
or two (or more) zone valves with one way going to heat the heatbank
and the other to the radiators. The boiler will handle both in
the most efficient way. It is pointless to make it any more
complicated than that.


..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Fri, 3 Sep 2004 00:24:58 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Thu, 2 Sep 2004 23:30:19 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Thu, 2 Sep 2004 23:01:54 +0100, "IMM" wrote:



The ideal heating boiler has some of the flow/ret sensors taken
off.

I am sure it *can*, but why screw up a perfectly good and
efficient
modulating boiler and wreck its efficiency?

The makers do not seem to think it is inefficient at all.

Wowee. Well they're not going to say "By the way, John, this is
not
the most efficient way to run a condensing boiler", are they?

You are confused in many respects. Very confused. All of a sudden he
is
a
boiler designer.

The principles are clearly explained in the link that I posted earlier
and are quite straightforward for anybody who understands the
principles of latent heat and a few other simple principles of
physics.

There is very little individual design left in condensing boilers on
the market today with all having quoted laboratory efficiency figures
within a percent or two at the most.

The question then becomes one of using the instrumentation of the
boiler effectively in order to maximise its efficiency by matching to
the load.

So does that web site mean the W-B boiler is pants?

Go and read it and decide for yourself.

Generically, a condensing boiler will have greater efficiency when run
at lower temperatures and when the rate of heat production matches the
characteristics of the load.

And there are various ways of doing that.

Having an effective control loop in
place with the boiler able to sense the operating load properly is the
best way to achieve that.

A good method but there are other ways.

After all, they still sell conventional
boilers and are quite pleased
with themselves about that.

The fact is that more efficient operation
by far happens at lower F&R
temperatures.

And that can be achieved by various methods.

The simple and most effective
one being to directly couple the boiler
to the heating circuit and let it use its
internal control systems
properly.

It isn't.

Actually it is.

Within the context of having the boiler in direct control of its load
with its internal control system and using analogue sensing vs. having
simple external sources turn it on and off, the former is clearly
going to be the most effective and efficient.

Not so.

Only the introduction of more sophisticated external controllers with
either PWM or analogue control of boiler modulation would improve on
the boiler internal control system in terms of oprating the boiler in
its most effcient range.

Not so.

For a normal domestic application this would be costly.

Again, not so.

"Andy Hall" wrote in message
...
On Fri, 03 Sep 2004 11:03:16 +0100, Pete C
wrote:

On Thu, 02 Sep 2004 22:25:46 +0100, Andy Hall
wrote:

On Thu, 2 Sep 2004 22:19:33 +0100, "IMM" wrote:

None modulate right down to zero. I think the best of them goes to
about 5
kW

Mine goes down to 3kW.

Oh well, I suppose it comes down to the cost of an extra heat
exchanger and pump vs the money saved by a cheaper boiler and reduced
boiler cycling.

I'd expect the heat loss when cycling is due to losses from the
boiler's heat exchanger when the water isn't being heated, and
shouldn't be too bad with a modulating condensing boiler using an
aluminium exhanger.

cheers,
Pete.

This was my point. You don't need an extra heat exchanger or pump.

You simply connect the modulating boiler via either a diverter valve
or two (or more) zone valves with one way going to heat the heatbank
and the other to the radiators. The boiler will handle both in
the most efficient way. It is pointless to make it any more
complicated than that.

The boiler will not have load compensation modulation control, so he is on
the right track.

"Pete C" wrote in message
...
On Thu, 02 Sep 2004 22:25:46 +0100, Andy Hall
wrote:

On Thu, 2 Sep 2004 22:19:33 +0100, "IMM" wrote:

None modulate right down to zero. I think the best of them goes to about
5
kW

Mine goes down to 3kW.

Oh well, I suppose it comes down to the cost of an extra heat
exchanger and pump vs the money saved by a cheaper boiler and reduced
boiler cycling.

I'd expect the heat loss when cycling is due to losses from the
boiler's heat exchanger when the water isn't being heated, and
shouldn't be too bad with a modulating condensing boiler using an
aluminium exhanger.

Are you still going for a heat heat bank?

On Sat, 4 Sep 2004 09:35:12 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Fri, 3 Sep 2004 00:24:58 +0100, "IMM" wrote:


Generically, a condensing boiler will have greater efficiency when run
at lower temperatures and when the rate of heat production matches the
characteristics of the load.

And there are various ways of doing that.

Putting a dampening element like a heatbank in the control loop is not
one of them.


Having an effective control loop in
place with the boiler able to sense the operating load properly is the
best way to achieve that.

A good method but there are other ways.

Adding other things will circumvent the boiler's control system and
unless properly instrumented with suitable analogue or analogue
equivalent sensors will not be able to improve on it.




Within the context of having the boiler in direct control of its load
with its internal control system and using analogue sensing vs. having
simple external sources turn it on and off, the former is clearly
going to be the most effective and efficient.

Not so.

Of course it is. Do you want me to demonstrate the behaviour of
control systems to you or can you provide a properly documented
reference with formulae?



Only the introduction of more sophisticated external controllers with
either PWM or analogue control of boiler modulation would improve on
the boiler internal control system in terms of oprating the boiler in
its most effcient range.

Not so.

For a normal domestic application this would be costly.

Again, not so.

You have already discussed adding in weather compensating boiler
controllers and extra valves and pumps. There's at least £250-350
cost in that lot. In the context of a boiler costing £500-900, which
would do the job perfectly well on its own, this is adding unnecessary
cost.

Added to which, if the boiler controller is not controlling the boiler
by analogue or analogue equivalent means it cannot possibly do a
better job than the boiler's internal modulation controls. The
simple external weather compensator boxes do not do that. They are
intended as an after-market add-on for non-modulating boilers and by
definition will not do as good a job as an analogue sensing internal
system.




..andy

To email, substitute .nospam with .gl

On Sat, 4 Sep 2004 09:39:31 +0100, "IMM" wrote:


"Andy Hall" wrote in message


You simply connect the modulating boiler via either a diverter valve
or two (or more) zone valves with one way going to heat the heatbank
and the other to the radiators. The boiler will handle both in
the most efficient way. It is pointless to make it any more
complicated than that.

The boiler will not have load compensation modulation control, so he is on
the right track.

Not if it is a simple external box with on/off control of the boiler.
If it is working, the best it can do is to cycle the boiler on and off
during heat demand periods of the room thermostat to reduce or
increase the average heat output. This is intended to compensate
in some way the thermal behaviour of the space being heated.

With a modulating, condensing boiler, there is absolutely no point in
doing this with this type of device because it simply cycles the
boiler when that doesn't need to happen.

If the boiler has the ability to have an external temperature sensor
connected which does give its controller an analogue reading of the
outside temperature, then that is worth having. However, this type of
boiler costs more, even though the sensor is cheap or even included.


..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Sat, 4 Sep 2004 09:35:12 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Fri, 3 Sep 2004 00:24:58 +0100, "IMM" wrote:


Generically, a condensing boiler will have greater efficiency when run
at lower temperatures and when the rate of heat production matches the
characteristics of the load.

And there are various ways of doing that.

Putting a dampening element like a heatbank in the control loop is not
one of them.

It is when appropriate weather compensating control is used, to ensure the
heat bank, or lower section of heat bank, is maintained at the variable
setpoint dictated by the compensator.

Having an effective control loop in
place with the boiler able to sense the operating load properly is the
best way to achieve that.

A good method but there are other ways.

Adding other things will circumvent
the boiler's control system

You have a boiler with a minimum control system.

Within the context of having the boiler in direct control of its load
with its internal control system and using analogue sensing vs. having
simple external sources turn it on and off, the former is clearly
going to be the most effective and efficient.

Not so.

Of course it is. Do you want me to demonstrate the behaviour of
control systems to you or can you provide a properly documented
reference with formulae?

You have to know what you are controlling before you apply control. You
don't.

Only the introduction of more sophisticated external controllers with
either PWM or analogue control of boiler modulation would improve on
the boiler internal control system in terms of oprating the boiler in
its most effcient range.

Not so.

For a normal domestic application this would be costly.

Again, not so.

You have already discussed adding in weather compensating boiler
controllers and extra valves and pumps.

1. compenstor
1. 3-way diverter valve
1. extra cyl stat
1. cheaper simpler boiler.

All in all works out about the same, and a superior more efficient system.

There's at least £250-350
cost in that lot. In the context of a boiler costing £500-900, which
would do the job perfectly well on its own, this is adding unnecessary
cost.

You don't understand these things.

Added to which, if the boiler controller is not controlling the boiler
by analogue or analogue equivalent means it cannot possibly do a
better job than the boiler's internal modulation controls.

What tripe!!!

The simple external weather compensator
boxes do not do that. They are
intended as an after-market add-on for
non-modulating boilers and by
definition will not do as good a job as an
analogue sensing internal system.

When combined with heat banks and heating a large mass of water matters are
very different. This you can't understand. This is very sad.

"Andy Hall" wrote in message
...
On Sat, 4 Sep 2004 09:39:31 +0100, "IMM" wrote:


"Andy Hall" wrote in message


You simply connect the modulating boiler via either a diverter valve
or two (or more) zone valves with one way going to heat the heatbank
and the other to the radiators. The boiler will handle both in
the most efficient way. It is pointless to make it any more
complicated than that.

The boiler will not have load compensation modulation control, so he is
on
the right track.

Not if it is a simple external box with on/off control of the boiler.
If it is working, the best it can do is to cycle the boiler on and off
during heat demand periods of the room thermostat to reduce or
increase the average heat output.

When he couples it to an "integrated" heat bank matters are very different.

On Sat, 4 Sep 2004 10:51:59 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Sat, 4 Sep 2004 09:35:12 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Fri, 3 Sep 2004 00:24:58 +0100, "IMM" wrote:


Generically, a condensing boiler will have greater efficiency when run
at lower temperatures and when the rate of heat production matches the
characteristics of the load.

And there are various ways of doing that.

Putting a dampening element like a heatbank in the control loop is not
one of them.

It is when appropriate weather compensating control is used, to ensure the
heat bank, or lower section of heat bank, is maintained at the variable
setpoint dictated by the compensator.

The heatbank will always introduce a dampening factor into the control
loop. The element that is intended to be controlled is the room
temperature, not the water temperature of the heatbank. The
weather compensator, if integrated with the boiler should move the
operating curve of the boiler up and down to match the load.

If you switch to maintaining the temperature of part of the heatbank
to maintain a set point according to the outside temperature, you
introduce a double control loop.

In the piece between the heatbank and the boiler, if you use the
typical separate box type of weather compensator, you will have an
analogue sensor for outside and one for inside, plus an input for a
switched room thermostat. The inside analogue sensor would
normally be used on the boiler return, but could be used on the return
from the radiators to the heatbank. Neither is ideal because
connecting it to the radiator return means that the controlled device
(boiler) has the damping effect of the heatbank in between which will
adversely influence the control loop. Having it on the boiler return
means that the temperature being monitored relates to heat use by the
heatbank and not the room space.

Then you have a switched control of the boiler - cycling it on and off
to attempt to maintain the temperature of the heatbank to a set point.
This is inefficient because you are then cycling the boiler.

All in all, a pointless exercise.



Having an effective control loop in
place with the boiler able to sense the operating load properly is the
best way to achieve that.

A good method but there are other ways.

Adding other things will circumvent
the boiler's control system

You have a boiler with a minimum control system.

There's no point. It's overall cheaper, better, more efficient and
simpler to have a modulating boiler with monitoring of its water
temperatures, connected to the radiators directly, and with a weather
compensating sensor able to provide temperature information (not just
on/off cycling).



Within the context of having the boiler in direct control of its load
with its internal control system and using analogue sensing vs. having
simple external sources turn it on and off, the former is clearly
going to be the most effective and efficient.

Not so.

Of course it is. Do you want me to demonstrate the behaviour of
control systems to you or can you provide a properly documented
reference with formulae?

You have to know what you are controlling before you apply control. You
don't.

It is very obvious what is being controlled. One part is the room
temperature. The other part is controlling the boiler firing level
most efficiently to match the room requirement. In the case of a
modulating, condensing boiler, this comes by maintaining the firing
rate at the minimum required rather than turning it on and off.
An external temperature sensor connected directly to the boiler to
provide it with external temperature info. directly will assist with
comfort on the one hand by increasing output above what is suggested
by room requirements when the outside temperature is falling, and
reducing it when the outside temperature is rising to reduce
overshoot.

In a system where the only source of heat input is a gas condensing
boiler, there is no point in putting a heat bank in the middle because
it simply distorts the control algorithm, and offers no advantages.

it also screws up the primary purpose of the heatbank, which is to
provide an energy store to deliver large amounts of energy quickly to
a heat exchanger.



Only the introduction of more sophisticated external controllers with
either PWM or analogue control of boiler modulation would improve on
the boiler internal control system in terms of oprating the boiler in
its most effcient range.

Not so.

For a normal domestic application this would be costly.

Again, not so.

You have already discussed adding in weather compensating boiler
controllers and extra valves and pumps.

1. compenstor
1. 3-way diverter valve
1. extra cyl stat
1. cheaper simpler boiler.

All in all works out about the same, and a superior more efficient system.

Neither statement is true.

There's at least £250-350
cost in that lot. In the context of a boiler costing £500-900, which
would do the job perfectly well on its own, this is adding unnecessary
cost.

..
A BEM5000 costs £188

A diverter valve costs £56

You forgot the extra pump to run the radiator circuit - £56 for a
Grundfos

All prices from Discounted Heating. Total cost is £311.

You can buy a Worcester Greenstar 28HE for £725 from them.

What 28kW condensing boiler you going to buy from Discounted Heating
for £410 that is any good?






Added to which, if the boiler controller is not controlling the boiler
by analogue or analogue equivalent means it cannot possibly do a
better job than the boiler's internal modulation controls.

What tripe!!!

Oh dear. Do you know nothing about the difference between analogue
or pseudo-analogue vs. switched control?



The simple external weather compensator
boxes do not do that. They are
intended as an after-market add-on for
non-modulating boilers and by
definition will not do as good a job as an
analogue sensing internal system.

When combined with heat banks and heating a large mass of water matters are
very different. This you can't understand. This is very sad.


Of course they are very different and I understand the difference
perfectly. The results, if using a condensing boiler as the sole
source of energy, will be inferior, by definition, than the direct
connection of the boiler to the radiators as the manufacturers intend
and design.

The value in a heatbank is in its ability to store energy at high
temperature to run a plate heat exchanger for the hot water. It is
also useful in the introduction of heat from other sources such as
solar.

It provides no value in a path between a modulating condensing boiler
and radiators. Even with all the extra controls that you describe,
the efficiency will be worsened. To suggest that coupling a
switching controller with a simple boiler is an improvement is
laughable.



..andy

To email, substitute .nospam with .gl

On Sat, 4 Sep 2004 10:55:22 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Sat, 4 Sep 2004 09:39:31 +0100, "IMM" wrote:


"Andy Hall" wrote in message


You simply connect the modulating boiler via either a diverter valve
or two (or more) zone valves with one way going to heat the heatbank
and the other to the radiators. The boiler will handle both in
the most efficient way. It is pointless to make it any more
complicated than that.

The boiler will not have load compensation modulation control, so he is
on
the right track.

Not if it is a simple external box with on/off control of the boiler.
If it is working, the best it can do is to cycle the boiler on and off
during heat demand periods of the room thermostat to reduce or
increase the average heat output.

When he couples it to an "integrated" heat bank matters are very different.



Yes. Worse if the sole source of heat is the condensing boiler.


..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Sat, 4 Sep 2004 10:51:59 +0100, "IMM" wrote:

It is when appropriate weather compensating
control is used, to ensure the
heat bank, or lower section of heat bank, is
maintained at the variable
setpoint dictated by the compensator.

The heatbank will always introduce a
dampening factor into the control
loop.

Not so. It will prevent/reduce boioer cycling that is for certain.

The element that is intended to be
controlled is the room
temperature, not the water temperature
of the heatbank.

Your comprehension is poor. The boiler/heat bank maintain the lowers section
of the heat bank at the temperature that the rads require for optimum
performance. That is very simple.

The weather compensator, if integrated
with the boiler should move the
operating curve of the boiler up and down
to match the load.

This weather compensator is NOT integrated with a boiler. This you can't
understand.

If you switch to maintaining the temperature
of part of the heatbank to maintain a set point
according to the outside temperature, you
introduce a double control loop.

Nope.

In the piece between the heatbank
and the boiler, if you use the
typical separate box type of weather
compensator, you will have an
analogue sensor for outside

Yes.

and one for inside,

?? One to sense the temp of the heat bank

plus an input for a
switched room thermostat.

Uh! Switched? room temp trimming is analogue unless to have a cheapo.

The inside analogue sensor would
normally be used on the boiler return,

Or boiler flow, which most operate on. Used on the heat bank here.

but could be used on the return
from the radiators to the heatbank.

Could be on the cylinder not far from the boiler/rads returns pipes.

Neither is ideal because
connecting it to the radiator
return means that the controlled device
(boiler) has the damping effect of the
heatbank in between which will
adversely influence the control loop.
Having it on the boiler return
means that the temperature being monitored
relates to heat use by the
heatbank and not the room space.

It is clear you do not understand. The rad circuits are off the bottom of
the heat bank and have their own pump. Easy. The boilers flow and return
is off the heat bank, at the bottom of the heat bank. The compensator has
a probe on the bottom section of the heat bank producing a mass of water at
the temp the rads require. The lower temp at the bottom on part load will
ensure low temp return for high efficient condenser operation, with an
expensive complex boiler.

You have to know what you are controlling
before you apply control. You
don't.

It is very obvious what is being controlled.
One part is the room temperature.

The room temp influence only trims.

The other part is controlling
the boiler firing level
most efficiently to match the room
requirement.

No. Get the boiler to heat a mass of water all at one time, to what
temperature the room requires.

In the case of a
modulating, condensing boiler,

No need for a modulating condensing boiler./ Most do modulate, but heating
boilers modulate on flow setpoint temp. As the boiler will be on full, when
heating the mass of water for CH very rare will it modulate.

In a system where the only source of heat input is a gas condensing
boiler, there is no point in putting a heat bank in the middle because
it simply distorts the control algorithm, and offers no advantages.

You still don't understand.

it also screws up the primary purpose
of the heatbank, which is to
provide an energy store to deliver
large amounts of energy quickly to
a heat exchanger.

Primary?

And to prevent boiler cycling and giving on-demand mains pressure hot water.
Eliminating cold water storage tanks. With a heat bank the DHW and CH
circuits don't care about the boiler. The boiler can be controlled more
efficiently by having it heat one mass of water very quickly and in one long
efficient burn. Taken further it can heat two masses of water at different
temperatures. High for DHW and low for CH. Taken further again, the CH mass
of water can be at variable temperatures to what the outside weather
dictates. When called to heat the CH mass of water it does it in one long
burn no matter what temperature the CH water mass is.

A BEM5000 costs £188

A diverter valve costs £56

You forgot the extra pump to run the radiator circuit - £56 for a
Grundfos

All prices from Discounted Heating. Total cost is £311.

You can buy a Worcester Greenstar 28HE for £725 from them.

What 28kW condensing boiler you going to buy from Discounted Heating
for £410 that is any good?

But you save a wedge on a 1.5K load compensating boiler and musch simpler.

When combined with heat banks and heating a large mass of water matters
are
very different. This you can't understand. This is very sad.

Of course they are very different
and I understand the difference
perfectly.

Not so.

The results, if using a condensing boiler as the sole
source of energy, will be inferior, by definition, than the direct
connection of the boiler to the radiators as the manufacturers intend
and design.

You clearly do not understand. "by definition, than the direct connection of
the boiler to the radiators as the manufacturers intend and design.". I am
not on about one of theses type of boiler.

The value in a heatbank is in its
ability to store energy at high
temperature to run a plate heat
exchanger for the hot water.

It is?

It is also useful in the introduction of
heat from other sources such as
solar.

...and a condensing boiler.

It provides no value in a path between
a modulating condensing boiler
and radiators.

You clearly do not understand.

Even with all the extra controls that you describe,
the efficiency will be worsened.

You clearly do not understand.

To suggest that coupling a
switching controller with a simple
boiler is an improvement is
laughable.

You clearly do not understand.