We are currently looking at updating our central heating and DHW. The
existing system is old and looks like it has been cobbled together at
various points in the past - for this reason and to facilitate other
house work, we are planning on putting the new boiler and DHW tank in
the loft.

Following research on google we have decided that an indirect Pandora
heatbank best fits our DHW needs (mains pressure is sufficient and the
ongoing safer operation vs a traditional unvented cylinder appeals to
SWMBO).

Apologies if the following appears to ramble - I am not an expert and
profess only to have gained my knowledge from this exceelent group and
many of the learned regular posters...

Not fully DIY but for reasons of speed and time we will be employing a
plumber to do the installing (I am however doing the
design/specifying). As seems to be the norm he was very reluctant when
I first mentioned the Heatbank to him and he was steering me towards an
unvented cylinder ...after running through the spec with him
(downloaded from DPS) in words of 1 syllable he has now come round to
the idea - probably as he can see the pre-plumbing of various parts
makes his life easier...!

The Pandora I have initially specified is 180l / 100kw / inlcuding two
2 port valves (S plan) that would serve heating/DHW.

Now the main issue - choosing an appropriate boiler to cater for the
heatbank and also serve the heating (radiator) system. Following
various discussions with my plumber we have calculated our heating
requirements at around 26kw and to err on the side of caution we are
looking at boilers between 28-31kw.

Following a number of positive posts and reserach into the features
offered by the Man Micromat (outside weather compensation/analogue
temperature DHW sensing/fully modulating pump etc etc) I have looked
into the Man Micromat H or HS series. I like the idea of these
features and also the ability (AIUI) to have a different set
temperature for DHW and a separate temperature for the heating.

Following considerable discussion with Eco Hometec they have raised a
number of issues that are bascially steeering me away from choosing the
Man:

1) The Man DHW probe can only sense temperatures upto 65deg - the
heatbank is suited to be heated to 75/80deg therefore not really
suitable. The Pandora has its own sensor(s) however these do not
directly feed into the boiler. Maybe this isn't a problem?

2) Due to the wiring of the Pandora (?) only one fixed temperature
output from the boiler will be provided therefore the separate setting
of temperatures for DHW/heating is not possible?

3) Due to number 2) the fully modulating room sensor and outside
weather compensator would not be required?

I am slightly confused as all of the literature I have read suggested
the ability to run separate temperatures for heating/DHW and now it
seems as though this isn't possible and therefore all of the additional
features the boiler is capable of are also not relevant? Unfortunately
am not expert enough in all this to argue the toss greatly so was
hoping for some additional input from the group?

a) Does the Pandora negate the need to have a "complex" boiler like the
Man?

b) Would a Pandora without zone valves etc team up with Man and its own
diverter etc?

Perhaps I should just be looking at a simpler 28-31kw boiler to avoid
any unecessary complications?

Many thanks to all replies in advance
Robin

On Sat, 20 May 2006 10:44:58 +0100, wrote
(in article . com):

We are currently looking at updating our central heating and DHW. The
existing system is old and looks like it has been cobbled together at
various points in the past - for this reason and to facilitate other
house work, we are planning on putting the new boiler and DHW tank in
the loft.

Following research on google we have decided that an indirect Pandora
heatbank best fits our DHW needs (mains pressure is sufficient and the
ongoing safer operation vs a traditional unvented cylinder appeals to
SWMBO).

Apologies if the following appears to ramble - I am not an expert and
profess only to have gained my knowledge from this exceelent group and
many of the learned regular posters...

Not fully DIY but for reasons of speed and time we will be employing a
plumber to do the installing (I am however doing the
design/specifying). As seems to be the norm he was very reluctant when
I first mentioned the Heatbank to him and he was steering me towards an
unvented cylinder ...after running through the spec with him
(downloaded from DPS) in words of 1 syllable he has now come round to
the idea - probably as he can see the pre-plumbing of various parts
makes his life easier...!

The Pandora I have initially specified is 180l / 100kw / inlcuding two
2 port valves (S plan) that would serve heating/DHW.

Now the main issue - choosing an appropriate boiler to cater for the
heatbank and also serve the heating (radiator) system. Following
various discussions with my plumber we have calculated our heating
requirements at around 26kw and to err on the side of caution we are
looking at boilers between 28-31kw.

Following a number of positive posts and reserach into the features
offered by the Man Micromat (outside weather compensation/analogue
temperature DHW sensing/fully modulating pump etc etc) I have looked
into the Man Micromat H or HS series. I like the idea of these
features and also the ability (AIUI) to have a different set
temperature for DHW and a separate temperature for the heating.

Following considerable discussion with Eco Hometec they have raised a
number of issues that are bascially steeering me away from choosing the
Man:

1) The Man DHW probe can only sense temperatures upto 65deg - the
heatbank is suited to be heated to 75/80deg therefore not really
suitable. The Pandora has its own sensor(s) however these do not
directly feed into the boiler. Maybe this isn't a problem?

2) Due to the wiring of the Pandora (?) only one fixed temperature
output from the boiler will be provided therefore the separate setting
of temperatures for DHW/heating is not possible?

3) Due to number 2) the fully modulating room sensor and outside
weather compensator would not be required?

I am slightly confused as all of the literature I have read suggested
the ability to run separate temperatures for heating/DHW and now it
seems as though this isn't possible and therefore all of the additional
features the boiler is capable of are also not relevant? Unfortunately
am not expert enough in all this to argue the toss greatly so was
hoping for some additional input from the group?

a) Does the Pandora negate the need to have a "complex" boiler like the
Man?

b) Would a Pandora without zone valves etc team up with Man and its own
diverter etc?

Perhaps I should just be looking at a simpler 28-31kw boiler to avoid
any unecessary complications?

Many thanks to all replies in advance
Robin


I have a Micromat and have been very pleased with it. I don't use it with a
heatbank because my mains flow rate is not adequate for my purposes. I
therefore went with a large (200l) fast recovery cylinder and kept the loft
tank. Considering possible water availability issues, I don't think that
this was a bad idea. However, had I had a decent flow rate, I might have
gone with a heatbank.

Let me make a few comments on the two parts of this:

It is desirable to run a heatbank at 80 degrees plus if you can for DHW
purposes, simply because you can store more energy and have a greater run
time before the store runs out. However, if the store is fairly large, as
you are suggesting, this may not be an issue. Keep in mind as well that
the boiler can be arranged to fire quite early on following a tap being
turned on and will start contributing heat back into the heatbank
immediately, thus lengthening run time.

I use the analogue temperature sensor for the DHW cylinder and it works
well.However, it is also possible to use a conventional thermostat if you
like.

Eco Hometec give quite good service, but in some areas, their knowledge of
the products is lacking. Their translation of the German manual is poor in
places and scant in others.



Let me answer a few of your points.

- The boiler temperature for DHW can be set to up to 70 degrees, not 65. I
just checked.

- You can have separate temperatures from the boiler for DHW and CH. I do
exactly this. It is a case of choosing the correct function number on the
boiler. I use number 38, which is not one that Eco Hometec was familiar
with. This uses the weather compensation sensor and the 2132 room
controller for the heating. It also allows the max flow temperature to be 85
degrees. There is a similar setting if it were preferred to use a
conventional room thermostat. As you have probably read, there is an
integral pump and on some models an internal diverter valve. I went for the
boiler without diverter valve because I wanted to have S-plan with a number
of valves.
In this case, the boiler has two mains outputs. Normally, only one is used
and is for operating an external diverter valve. This behaviour happens for
the low numbered function settings and the second output isn't used.

However, in the higher number modes, the second output is intended to drive
an external pump when in heating mode. The complete S-plan solution then
becomes easy. The first output is used to control a zone valve for the HW
cylinder or heatbank. The second for a zone valve for the heating.
Behaviour is then as follows:

- With heating turned on, the boiler runs based on the weather compensator
and room sensor/thermostat. It *can* run at up to 85 degrees flow, but
doesn't. I moved radiators around and replaced some such that I can get
enough heat to deal with the standard -3 degree outside temperature with the
boiler running at 70 degree flow and 50 degree return. In practice, it is
unusual for the flow to exceed 60 degrees except following startup on the
coldest days. Quite often, the flow is as low as 40 degrees and the boiler
sits running all day like that.

- As soon as there is DHW demand, the boiler cuts power to the second
output, closing the CH zone valve(s) and powers the first output, opening the
cylinder zone valve. It then fires up to full output and flow temperature
rising to 85 degrees output.

So to summarise:

- It's a good boiler and you could team it up quite easily with a heatbank or
fast recovery cylinder

- You could heat the heatbank to 70 degrees using the analogue sensor or more
if you went for a conventional cyllinder thermostat or better an electronic
on/off one with cylinder sensor. Danfoss Randall and others make these.
The advantage compared with a crude bimetallic strip type is that they have
better accuracy and tighter hysteresis. The analogue sensor does give the
boiler information about the actual temperature as opposed to a
demand/satisfied signal, but other than detecting the temperature fall when
a tap is turned on slightly earlier, I don't think that a lot is lost.

- There is a considerable advantage in having the outside temperature
detection and the fully modulated pump for CH purposes. You get much better
control and behaviour of the system in terms of temperature stability plus
the lower average running temperatures for the circuit and greater running
efficiency.

- I would go for the Micromat without diverter and drive the heatbank
directly with it. The boiler will drive the CH very well and control it
on its own. I would buy one again.


/andy

Andy,

Many thanks for your thorough and speedy response. If I may just raise
a few issues/questions underneath snipped parts of your post:


It is desirable to run a heatbank at 80 degrees plus if you can for DHW
purposes, simply because you can store more energy and have a greater run
time before the store runs out. However, if the store is fairly large, as
you are suggesting, this may not be an issue. Keep in mind as well that
the boiler can be arranged to fire quite early on following a tap being
turned on and will start contributing heat back into the heatbank
immediately, thus lengthening run time.

As per normal usage ie cylinder stat or similar kicking in or via the
installation of a flow switch? Under normal usage conditions I agree
that heating to 70 degrees should be sufficient with a 180l store.


I use the analogue temperature sensor for the DHW cylinder and it works
well.However, it is also possible to use a conventional thermostat if you
like.

The Pandora can come with 1 or 2 immersed Danfoss stats that sound very
similar to the Man immersed stat - I had considered a straight
replacement for the Man one but given the benefit of reaching a higher
temperature it is probably better to opt for the Pandora's own. The
issue I have is how to decipher the wiring back into the boiler as
Eco's stressed that the boiler is primarliy designed for low voltage
connections ie the Man RE2132 unit/outside weather compensator and
cylinder probe all attach via the low voltage rail whereas the heatbank
cylinder probe(s) would be wired into the wiring centre on the heatbank
itself?

Let me answer a few of your points.

- The boiler temperature for DHW can be set to up to 70 degrees, not 65. I
just checked.

- You can have separate temperatures from the boiler for DHW and CH. I do
exactly this. It is a case of choosing the correct function number on the
boiler. I use number 38, which is not one that Eco Hometec was familiar
with. This uses the weather compensation sensor and the 2132 room
controller for the heating. It also allows the max flow temperature to be 85
degrees. There is a similar setting if it were preferred to use a
conventional room thermostat. As you have probably read, there is an
integral pump and on some models an internal diverter valve. I went for the
boiler without diverter valve because I wanted to have S-plan with a number
of valves.

So no additional diverter in your system or you use an external
diverter in addition to the zone valves?

In this case, the boiler has two mains outputs. Normally, only
one is used
and is for operating an external diverter valve. This behaviour happens for
the low numbered function settings and the second output isn't used.

However, in the higher number modes, the second output is intended to drive
an external pump when in heating mode. The complete S-plan solution then
becomes easy. The first output is used to control a zone valve for the HW
cylinder or heatbank. The second for a zone valve for the heating.
Behaviour is then as follows:

- With heating turned on, the boiler runs based on the weather compensator
and room sensor/thermostat. It *can* run at up to 85 degrees flow, but
doesn't. I moved radiators around and replaced some such that I can get
enough heat to deal with the standard -3 degree outside temperature with the
boiler running at 70 degree flow and 50 degree return. In practice, it is
unusual for the flow to exceed 60 degrees except following startup on the
coldest days. Quite often, the flow is as low as 40 degrees and the boiler
sits running all day like that.

- As soon as there is DHW demand, the boiler cuts power to the second
output, closing the CH zone valve(s) and powers the first output, opening the
cylinder zone valve. It then fires up to full output and flow temperature
rising to 85 degrees output.

Do you utlise a wiring centre in your setup or do you wire each of the
valves back to the boiler?

This is what I thought I was specifying on the Heatbank ie separate
zone valves for DHW and CH however the issue seemed to be that these
are pre wired into the wiring centre on the Heatbank and for
convenience you have one mains wire intended to go into the boiler (3
perm L N and E and a switched live) - AIUI the boiler is primarily
intended to function via low voltage connections therefore I would need
to install a relay of some kind but even then I couldn't really figure
if this is how the boiler is intended to pick up these signals or not?

I did speak to them about this and considered the HS model as it has 2
flows and 2 returns and I could separate one each for the heatbank and
heating and utilise the internal diverter to do the work however Eco's
suggested that this with contra building regs that required the usage
of additional zone valves - I didn't argue further as I haven't read
the necessary regs in that much detail but it sounded at odds with
logic if the boiler has separate flows and returns for each section and
it has it's own diverter then surely if it's wired up correctly then
there should only be calls on the boiler when required, why would I
need further valves?


So to summarise:

- It's a good boiler and you could team it up quite easily with a heatbank or
fast recovery cylinder

- You could heat the heatbank to 70 degrees using the analogue sensor or more
if you went for a conventional cyllinder thermostat or better an electronic
on/off one with cylinder sensor. Danfoss Randall and others make these.
The advantage compared with a crude bimetallic strip type is that they have
better accuracy and tighter hysteresis. The analogue sensor does give the
boiler information about the actual temperature as opposed to a
demand/satisfied signal, but other than detecting the temperature fall when
a tap is turned on slightly earlier, I don't think that a lot is lost.

- There is a considerable advantage in having the outside temperature
detection and the fully modulated pump for CH purposes. You get much better
control and behaviour of the system in terms of temperature stability plus
the lower average running temperatures for the circuit and greater running
efficiency.

- I would go for the Micromat without diverter and drive the heatbank
directly with it. The boiler will drive the CH very well and control it
on its own. I would buy one again.

Utlising the pre plumbed S plan setup? if so then this seemed to me to
be the best approach however what with the possible issues over wiring
and some of the information I have had back I have rethought my
original plan and ended up confusing myself even more I think!


/andy

On Sat, 20 May 2006 16:47:56 +0100, wrote
(in article .com):

Andy,

Many thanks for your thorough and speedy response. If I may just raise
a few issues/questions underneath snipped parts of your post:


It is desirable to run a heatbank at 80 degrees plus if you can for DHW
purposes, simply because you can store more energy and have a greater run
time before the store runs out. However, if the store is fairly large, as
you are suggesting, this may not be an issue. Keep in mind as well that
the boiler can be arranged to fire quite early on following a tap being
turned on and will start contributing heat back into the heatbank
immediately, thus lengthening run time.

As per normal usage ie cylinder stat or similar kicking in or via the
installation of a flow switch? Under normal usage conditions I agree
that heating to 70 degrees should be sufficient with a 180l store.

In my case, with the analogue sensor, it is installed in a pocket in the
cylinder. Basically this is a tube into the side of the cylinder with
stopped end. The probe is inserted into it and is thus is sensing the
temperature in the centre and not surface of the cylinder. It appears that
the behaviour of the boiler controller is to sense the rate of fall of
temperature of this as well as the absolute temperature. Normally there is a
hysteresis of about 5 degrees so that the boiler doesn't fire until 55
degrees is reached when the temperature is dropping slowly - i.e. small
amounts of water used. However, if a bath or shower is started, the boiler
begins to fire very quickly (less than a minute) and before the temperature
display has hit 55 degrees. I run the cylinder at 60, I should add.

You could use a flow switch, of course, but you would also need a thermostat
to make sure that the cylinder is brought back up to tempertature after the
flow stops.




I use the analogue temperature sensor for the DHW cylinder and it works
well.However, it is also possible to use a conventional thermostat if you
like.

The Pandora can come with 1 or 2 immersed Danfoss stats that sound very
similar to the Man immersed stat - I had considered a straight
replacement for the Man one but given the benefit of reaching a higher
temperature it is probably better to opt for the Pandora's own.

The principle is different. The MAN one is a temperature sensor. The boiler
is able to know the actual temperature and work with that - cylinder temp is
set on the boiler. With a thermostat, the boiler is only given a signal
to fire or not. If you are going to go for a thermostat, try to get one
that is electronic rather than bimetal strip or capillary. these tend to be
rather crude on setting and sensing.




The
issue I have is how to decipher the wiring back into the boiler as
Eco's stressed that the boiler is primarliy designed for low voltage
connections ie the Man RE2132 unit/outside weather compensator and
cylinder probe all attach via the low voltage rail whereas the heatbank
cylinder probe(s) would be wired into the wiring centre on the heatbank
itself?

If the thermostat has no-volt contacts - meaning a switch contact rather than
wanting to feed mains, then you can use low voltage wiring.

However, if you do, then it would be a good idea to keep this wiring
completely separate and not connect it in the wiring centre, but put in a
separate one.





Let me answer a few of your points.

- The boiler temperature for DHW can be set to up to 70 degrees, not 65. I
just checked.

- You can have separate temperatures from the boiler for DHW and CH. I do
exactly this. It is a case of choosing the correct function number on the
boiler. I use number 38, which is not one that Eco Hometec was familiar
with. This uses the weather compensation sensor and the 2132 room
controller for the heating. It also allows the max flow temperature to be
85
degrees. There is a similar setting if it were preferred to use a
conventional room thermostat. As you have probably read, there is an
integral pump and on some models an internal diverter valve. I went for
the
boiler without diverter valve because I wanted to have S-plan with a number
of valves.

So no additional diverter in your system or you use an external
diverter in addition to the zone valves?


No additional diverter. The boiler opens the relevant zone valve according
to whether CH or DHW is being done. DHW has preference.




In this case, the boiler has two mains outputs. Normally, only
one is used
and is for operating an external diverter valve. This behaviour happens
for
the low numbered function settings and the second output isn't used.

However, in the higher number modes, the second output is intended to drive
an external pump when in heating mode. The complete S-plan solution then
becomes easy. The first output is used to control a zone valve for the HW
cylinder or heatbank. The second for a zone valve for the heating.
Behaviour is then as follows:

- With heating turned on, the boiler runs based on the weather compensator
and room sensor/thermostat. It *can* run at up to 85 degrees flow, but
doesn't. I moved radiators around and replaced some such that I can get
enough heat to deal with the standard -3 degree outside temperature with the
boiler running at 70 degree flow and 50 degree return. In practice, it is
unusual for the flow to exceed 60 degrees except following startup on the
coldest days. Quite often, the flow is as low as 40 degrees and the
boiler
sits running all day like that.

- As soon as there is DHW demand, the boiler cuts power to the second
output, closing the CH zone valve(s) and powers the first output, opening
the
cylinder zone valve. It then fires up to full output and flow temperature
rising to 85 degrees output.

Do you utlise a wiring centre in your setup or do you wire each of the
valves back to the boiler?

I used two wiring centres (one mains and one low voltage) near the cylinder
because that is where the zone valves are located. Wiring from these runs
back to the boiler. Actually wiring is simple, because there only needs to
be mains on/off to open the valves. The sensors are individually run.





This is what I thought I was specifying on the Heatbank ie separate
zone valves for DHW and CH however the issue seemed to be that these
are pre wired into the wiring centre on the Heatbank and for
convenience you have one mains wire intended to go into the boiler (3
perm L N and E and a switched live) - AIUI the boiler is primarily
intended to function via low voltage connections therefore I would need
to install a relay of some kind but even then I couldn't really figure
if this is how the boiler is intended to pick up these signals or not?

I did speak to them about this and considered the HS model as it has 2
flows and 2 returns and I could separate one each for the heatbank and
heating and utilise the internal diverter to do the work however Eco's
suggested that this with contra building regs that required the usage
of additional zone valves - I didn't argue further as I haven't read
the necessary regs in that much detail but it sounded at odds with
logic if the boiler has separate flows and returns for each section and
it has it's own diverter then surely if it's wired up correctly then
there should only be calls on the boiler when required, why would I
need further valves?

That's making it all unnecessarily complicated. You don't need zone valves
on the heatbank, nor do you need them in the boiler.

If the only way that you can buy the heatbank is with a switched live output,
then you would need an additional relay to provide volt free switching to the
boiler. I would ask DPS for a wiring diagram of what they supply. It
sounds as though it's a package intended to work with a simple boiler and to
have all the controls to make a drop in installation with such a boiler. I
think that you would be better off specifiying it without all the extra
gubbins that you don't really need.




So to summarise:

- It's a good boiler and you could team it up quite easily with a heatbank
or
fast recovery cylinder

- You could heat the heatbank to 70 degrees using the analogue sensor or
more
if you went for a conventional cyllinder thermostat or better an electronic
on/off one with cylinder sensor. Danfoss Randall and others make these.
The advantage compared with a crude bimetallic strip type is that they have
better accuracy and tighter hysteresis. The analogue sensor does give the
boiler information about the actual temperature as opposed to a
demand/satisfied signal, but other than detecting the temperature fall when
a tap is turned on slightly earlier, I don't think that a lot is lost.

- There is a considerable advantage in having the outside temperature
detection and the fully modulated pump for CH purposes. You get much
better
control and behaviour of the system in terms of temperature stability plus
the lower average running temperatures for the circuit and greater running
efficiency.

- I would go for the Micromat without diverter and drive the heatbank
directly with it. The boiler will drive the CH very well and control it
on its own. I would buy one again.

Utlising the pre plumbed S plan setup?

I didn't do anything pre-plumbed. The wiring and plumbing were simpler
without.


if so then this seemed to me to
be the best approach however what with the possible issues over wiring
and some of the information I have had back I have rethought my
original plan and ended up confusing myself even more I think!


/andy

Thanks again Andy, the situation does seem a little clearer to me - it
is only that involving an external party (installer) in my installation
means additional complications especially as the boiler isn't an "off
the shelf" product it seems to be easier for him to say it can't be
done etc as opposed to looking into things in a bit more detail.
Perhaps I should be finding someone who is a little more flexible...

Apologies for continually rehashing my questioning but you seem to have
the practical input that neither DPS nor Eco's could feed back to me,
you don't do callouts do you !?

If I go for H series boiler and no additonal zone valves on the
heatbank I will still need some form of diverter (either from Eco's or
an off the shelf diverter?) presumably so the flow can be directed
appropriately? The wiring for this seems straighforward and goes
directly into the mains rail of the boiler?

I can specify a Heatbank without any additional zone valves ie the only
additional items on the cylinder are a circulating pump / flow switch /
backup immersion element (DHW controls) and thermostats (only item
affecting boiler behaviour). The suggested wiring diagram for this
setup appears relatively strightforward however it still outputs a
single swiched live to the boiler, however, I don't see that this is
any dfferent to standard cylinder installation and akin to the type 2
installation schematic on the MHS technical manual? The Eco manual is a
little lacking here and they describe the equivalent as the wiring for
the room stat however whether it's room stat or cylinder stat the
boiler should know that it is being called upon and fire up and then
the diverter should take care of diverting the flow appropriately?

AIUI the heating side would then just be a case of wiring in the low
voltage outside weather compensator and RE2132 onto the low voltage
rail?

Thanks again in advance
Robin

On Sun, 21 May 2006 09:54:42 +0100, wrote
(in article . com):

Thanks again Andy, the situation does seem a little clearer to me - it
is only that involving an external party (installer) in my installation
means additional complications especially as the boiler isn't an "off
the shelf" product it seems to be easier for him to say it can't be
done etc as opposed to looking into things in a bit more detail.
Perhaps I should be finding someone who is a little more flexible...

Apologies for continually rehashing my questioning but you seem to have
the practical input that neither DPS nor Eco's could feed back to me,
you don't do callouts do you !?

If I go for H series boiler and no additonal zone valves on the
heatbank I will still need some form of diverter (either from Eco's or
an off the shelf diverter?) presumably so the flow can be directed
appropriately? The wiring for this seems straighforward and goes
directly into the mains rail of the boiler?


You could either use a diverter valve arranged so that when energised, flow
goes to the cylinder, or you could use a zone valve for the cylinder from the
same output and then a second zone valve for the CH run from the second
output normally used for an auxilliary CH pump. I went for the latter
approach because I needed to run a second heating circuit for some additional
radiators and it was much more convenient to take that from nearer the boiler
than after the normal split in the flow some metres away. I simply wire both
CH zone valves to the second output





I can specify a Heatbank without any additional zone valves ie the only
additional items on the cylinder are a circulating pump / flow switch /
backup immersion element (DHW controls) and thermostats (only item
affecting boiler behaviour). The suggested wiring diagram for this
setup appears relatively strightforward however it still outputs a
single swiched live to the boiler, however, I don't see that this is
any dfferent to standard cylinder installation and akin to the type 2
installation schematic on the MHS technical manual? The Eco manual is a
little lacking here and they describe the equivalent as the wiring for
the room stat however whether it's room stat or cylinder stat the
boiler should know that it is being called upon and fire up and then
the diverter should take care of diverting the flow appropriately?

You could do that. All that would then be needed is an additional relay run
from this output from the cylinder wiring and then used to provide contacts
for the boiler.

The boiler will provide a live to open the DHW zone valve.



AIUI the heating side would then just be a case of wiring in the low
voltage outside weather compensator and RE2132 onto the low voltage
rail?

If you use the RE2132 then that goes directly to the boiler LV rail as you
say, along with the outside sensor connection





Thanks again in advance
Robin

"Andy Hall" aka Matt wrote in message
...
On Sat, 20 May 2006 10:44:58 +0100, wrote
(in article . com):

We are currently looking at updating our central heating and DHW. The
existing system is old and looks like it has been cobbled together at
various points in the past - for this reason and to facilitate other
house work, we are planning on putting the new boiler and DHW tank in
the loft.

Following research on google we have decided that an indirect Pandora
heatbank best fits our DHW needs (mains pressure is sufficient and the
ongoing safer operation vs a traditional unvented cylinder appeals to
SWMBO).

Apologies if the following appears to ramble - I am not an expert and
profess only to have gained my knowledge from this exceelent group and
many of the learned regular posters...

Not fully DIY but for reasons of speed and time we will be employing a
plumber to do the installing (I am however doing the
design/specifying). As seems to be the norm he was very reluctant when
I first mentioned the Heatbank to him and he was steering me towards an
unvented cylinder ...after running through the spec with him
(downloaded from DPS) in words of 1 syllable he has now come round to
the idea - probably as he can see the pre-plumbing of various parts
makes his life easier...!

The Pandora I have initially specified is 180l / 100kw / inlcuding two
2 port valves (S plan) that would serve heating/DHW.

Now the main issue - choosing an appropriate boiler to cater for the
heatbank and also serve the heating (radiator) system. Following
various discussions with my plumber we have calculated our heating
requirements at around 26kw and to err on the side of caution we are
looking at boilers between 28-31kw.

Following a number of positive posts and reserach into the features
offered by the Man Micromat (outside weather compensation/analogue
temperature DHW sensing/fully modulating pump etc etc) I have looked
into the Man Micromat H or HS series. I like the idea of these
features and also the ability (AIUI) to have a different set
temperature for DHW and a separate temperature for the heating.

Following considerable discussion with Eco Hometec they have raised a
number of issues that are bascially steeering me away from choosing the
Man:

1) The Man DHW probe can only sense temperatures upto 65deg - the
heatbank is suited to be heated to 75/80deg therefore not really
suitable. The Pandora has its own sensor(s) however these do not
directly feed into the boiler. Maybe this isn't a problem?

2) Due to the wiring of the Pandora (?) only one fixed temperature
output from the boiler will be provided therefore the separate setting
of temperatures for DHW/heating is not possible?

3) Due to number 2) the fully modulating room sensor and outside
weather compensator would not be required?

I am slightly confused as all of the literature I have read suggested
the ability to run separate temperatures for heating/DHW and now it
seems as though this isn't possible and therefore all of the additional
features the boiler is capable of are also not relevant? Unfortunately
am not expert enough in all this to argue the toss greatly so was
hoping for some additional input from the group?

a) Does the Pandora negate the need to have a "complex" boiler like the
Man?

b) Would a Pandora without zone valves etc team up with Man and its own
diverter etc?

Perhaps I should just be looking at a simpler 28-31kw boiler to avoid
any unecessary complications?

Many thanks to all replies in advance
Robin


I have a Micromat and have been very pleased with it. I don't use it
with a
heatbank because my mains flow rate is not adequate for my purposes. I
therefore went with a large (200l) fast recovery cylinder and kept the
loft
tank. Considering possible water availability issues, I don't think that
this was a bad idea. However, had I had a decent flow rate, I might have
gone with a heatbank.

Let me make a few comments on the two parts of this:

It is desirable to run a heatbank at 80 degrees plus if you can for DHW
purposes, simply because you can store more energy and have a greater run
time before the store runs out. However, if the store is fairly large,
as
you are suggesting, this may not be an issue. Keep in mind as well that
the boiler can be arranged to fire quite early on following a tap being
turned on and will start contributing heat back into the heatbank
immediately, thus lengthening run time.

I use the analogue temperature sensor for the DHW cylinder and it works
well.However, it is also possible to use a conventional thermostat if you
like.

Eco Hometec give quite good service, but in some areas, their knowledge of
the products is lacking. Their translation of the German manual is poor
in
places and scant in others.



Let me answer a few of your points.

- The boiler temperature for DHW can be set to up to 70 degrees, not 65. I
just checked.

- You can have separate temperatures from the boiler for DHW and CH. I do
exactly this. It is a case of choosing the correct function number on
the
boiler. I use number 38, which is not one that Eco Hometec was familiar
with. This uses the weather compensation sensor and the 2132 room
controller for the heating. It also allows the max flow temperature to be
85
degrees. There is a similar setting if it were preferred to use a
conventional room thermostat. As you have probably read, there is an
integral pump and on some models an internal diverter valve. I went for
the
boiler without diverter valve because I wanted to have S-plan with a
number
of valves.
In this case, the boiler has two mains outputs. Normally, only one is
used
and is for operating an external diverter valve. This behaviour happens
for
the low numbered function settings and the second output isn't used.

However, in the higher number modes, the second output is intended to
drive
an external pump when in heating mode. The complete S-plan solution then
becomes easy. The first output is used to control a zone valve for the
HW
cylinder or heatbank. The second for a zone valve for the heating.
Behaviour is then as follows:

- With heating turned on, the boiler runs based on the weather compensator
and room sensor/thermostat. It *can* run at up to 85 degrees flow, but
doesn't. I moved radiators around and replaced some such that I can get
enough heat to deal with the standard -3 degree outside temperature with
the
boiler running at 70 degree flow and 50 degree return. In practice, it
is
unusual for the flow to exceed 60 degrees except following startup on the
coldest days. Quite often, the flow is as low as 40 degrees and the
boiler
sits running all day like that.

- As soon as there is DHW demand, the boiler
cuts power to the second output, closing the CH
zone valve(s) and powers the first output, opening the
cylinder zone valve. It then fires up to full output
and flow temperature rising to 85 degrees output.

Matt, how does your boiler model know that DHW is calling if fitted with
either a stat or temp sensor?



So to summarise:

- It's a good boiler and you could team it up quite easily with a heatbank
or
fast recovery cylinder

- You could heat the heatbank to 70 degrees using the analogue sensor or
more
if you went for a conventional cyllinder thermostat or better an
electronic
on/off one with cylinder sensor. Danfoss Randall and others make these.
The advantage compared with a crude bimetallic strip type is that they
have
better accuracy and tighter hysteresis. The analogue sensor does give
the
boiler information about the actual temperature as opposed to a
demand/satisfied signal, but other than detecting the temperature fall
when
a tap is turned on slightly earlier, I don't think that a lot is lost.

- There is a considerable advantage in having the outside temperature
detection and the fully modulated pump for CH purposes. You get much
better
control and behaviour of the system in terms of temperature stability plus
the lower average running temperatures for the circuit and greater running
efficiency.

- I would go for the Micromat without diverter and drive the heatbank
directly with it. The boiler will drive the CH very well and control
it
on its own. I would buy one again.


/andy

On Sat, 20 May 2006 19:02:49 +0100, Doctor Drivel wrote
(in article ews.net):


"Andy Hall" aka Matt wrote in message
...
..

- As soon as there is DHW demand, the boiler
cuts power to the second output, closing the CH
zone valve(s) and powers the first output, opening the
cylinder zone valve. It then fires up to full output
and flow temperature rising to 85 degrees output.

Matt, how does your boiler model know that DHW is calling if fitted with
either a stat or temp sensor?




There is a setting on the controller in the boiler to select whether the DHW
demand sensing is by a contact closure (i.e. thermostat) or a temperature
sensor.

There is a similar one for CH control where the sensing is between thermostat
contact, a PWM signal from a Siemens or other controller or 0-10 or 0-3v
analogue control.

"Andy Hall" aka Matt wrote in message
...
On Sat, 20 May 2006 19:02:49 +0100, Doctor Drivel wrote
(in article ews.net):


"Andy Hall" aka Matt wrote in message
...
.

- As soon as there is DHW demand, the boiler
cuts power to the second output, closing the CH
zone valve(s) and powers the first output, opening the
cylinder zone valve. It then fires up to full output
and flow temperature rising to 85 degrees output.

Matt, how does your boiler model know
that DHW is calling if fitted with
either a stat or temp sensor?

There is a setting on the controller in
the boiler to select whether the DHW
demand sensing is by a contact closure
(i.e. thermostat) or a temperature
sensor.

When a stat detects DHW is calling the boiler just then runs up to what the
maximum temperature the boiler is set at? Demand sensing - this will be a
DHW setpoint (cylinder temp) set at the boiler. Below and the boioer runs up
the the max boioer temp set?

There is a similar one for CH control
where the sensing is between thermostat
contact, a PWM signal from a Siemens or
other controller or 0-10 or 0-3v analogue control.

External control which incorporates the burner modualtion rather than
on-off.

On Sun, 21 May 2006 10:08:05 +0100, Doctor Drivel wrote
(in article ews.net):


"Andy Hall" aka Matt wrote in message
...
On Sat, 20 May 2006 19:02:49 +0100, Doctor Drivel wrote
(in article ews.net):


"Andy Hall" aka Matt wrote in message
...
.

- As soon as there is DHW demand, the boiler
cuts power to the second output, closing the CH
zone valve(s) and powers the first output, opening the
cylinder zone valve. It then fires up to full output
and flow temperature rising to 85 degrees output.

Matt, how does your boiler model know
that DHW is calling if fitted with
either a stat or temp sensor?

There is a setting on the controller in
the boiler to select whether the DHW
demand sensing is by a contact closure
(i.e. thermostat) or a temperature
sensor.

When a stat detects DHW is calling the boiler just then runs up to what the
maximum temperature the boiler is set at?

Exactly.


Demand sensing - this will be a
DHW setpoint (cylinder temp) set at the boiler. Below and the boioer runs up
the the max boioer temp set?

Yes again.



There is a similar one for CH control
where the sensing is between thermostat
contact, a PWM signal from a Siemens or
other controller or 0-10 or 0-3v analogue control.

External control which incorporates the burner modualtion rather than
on-off.



Yep. (You're getting good at this :-) )

The Siemens (was Landis & Gyr) RE2132 controller which is specifically
intended for this boiler, AFAIK, (possibly special firmware), has a setting
to adjust the relative balance between the external weather sensor and
internal sensing. Thus one can have different response behaviour according
to nature of house. It takes care of optimised start as well.

The other input methods are used in commercial applications when multiple
boilers are cascaded and a cascading controller is used to handle up to 9 of
the boilers.

"Andy Hall" aka Matt wrote in message
...

There is a similar one for CH control where the sensing is between
thermostat
contact, a PWM signal from a Siemens or other controller or 0-10 or 0-3v
analogue control.

A cheap controller sensing the room temperature with 0-10v ouput will
modulate the burner to suit the room temp.

On Sat, 20 May 2006 02:44:58 -0700, wrote:

... we are planning on putting the new boiler and DHW tank in
the loft.

Following research on google we have decided that an indirect Pandora
heatbank best fits our DHW needs
....
The Pandora I have initially specified is 180l / 100kw / inlcuding two
2 port valves (S plan) that would serve heating/DHW.

That's going to be fun to get into your loft!
(and to site safely)

Now the main issue - choosing an appropriate boiler to cater for the
heatbank and also serve the heating (radiator) system. Following
various discussions with my plumber we have calculated our heating
requirements at around 26kw and to err on the side of caution we are
looking at boilers between 28-31kw.

That's an awful lot of heat. How many rooms does your mansion have, to the
nearest dozen? :-)

Have you checked with the whole-house calculations on

http://www.est.org.uk/housingbuildin.../boilersizing/

and

http://www.idhe.org.uk/calculator.html

(Note that the latter is wrong for mid-floor flats, at least.)

I'd expect to size a boiler at around 10-15kW for normal sized houses.
OTOH if you can afford a Pandora and a MAN then maybe you also have a
house with that sort of heating requirement :-)

"John Stumbles" wrote in message
news
Now the main issue - choosing an appropriate boiler to cater for the
heatbank and also serve the heating (radiator) system. Following
various discussions with my plumber we have calculated our heating
requirements at around 26kw and to err on the side of caution we are
looking at boilers between 28-31kw.

That's an awful lot of heat. How many rooms
does your mansion have, to the
nearest dozen? :-)

The MAN can go down to 3kW so not a problem for the CH, but will heat the
Pandora zippo with DHW priority.

Or he could use a Glow Worm condensing boiler, (modulates down to 5kW) and a
stand alone Danfoss BEM 5000 weather compensator (about £190), with has the
cyl' stat wired directly into it and gives full heat of DHW and weather
compensted on CH. The compensator may be giving a CH flow temp of 45C, but
when DHW is called the full 80C is given to the cylinder, modulating down
when near heated.

I have looked at the glow worm and it is considerably cheaper and out
of what is available seems to be a reasonable product. If I can't get
suitable answers from DPS and Eco Hometec regarding the Man and the
Pandora then I may yet go down this route.

I have looked at the glow worm and it is considerably cheaper and out
of what is available seems to be a reasonable product. If I can't get
suitable answers from DPS and Eco Hometec regarding the Man and the
Pandora then I may yet go down this route.

Also, consider the Worcester Bosch Greenstar with additional diverter valve
(assuming they still make it in the new range). This allows separate
temperature settings for DHW and CH. Technically, the DHW is (or was in the
previous version) limited to 75C and the CH is limited to 85C, but we
couldn't see a reason why you couldn't swap the circuits, although a relay
might be required to get DHW priority instead of CH priority.

This way, the boiler can produce 82-85C for the Pandora and drop to 60C for
the CH, which is safer and more efficient.

I have the WB and the Pandora, but didn't specify the diverter, which I
probably regret now, as I have to run the rads too hot.

Christian.

"Christian McArdle" wrote in message
...
I have looked at the glow worm and it is considerably cheaper and out
of what is available seems to be a reasonable product. If I can't get
suitable answers from DPS and Eco Hometec regarding the Man and the
Pandora then I may yet go down this route.

Also, consider the Worcester Bosch Greenstar with additional diverter
valve
(assuming they still make it in the new range). This allows separate
temperature settings for DHW and CH.

I tried to get info from W-B on this and I'm sure they said you can't have
two temps.

Technically, the DHW is (or was in the
previous version) limited to 75C and the CH is limited to 85C, but we
couldn't see a reason why you couldn't swap the circuits, although a relay
might be required to get DHW priority instead of CH priority.

This way, the boiler can produce 82-85C for the Pandora and drop to 60C
for
the CH, which is safer and more efficient.

I have the WB and the Pandora, but didn't specify the diverter, which I
probably regret now, as I have to run the rads too hot.

Buy a Danfoss BEM 5000, that will do they job for you. I saw one on ebay
that went for £22 brand new plus £5 postage. ~£200 worth of compensator for
buttons. Most don't understand them and can't see what they can get from
them, thinking a modulating boiler is the answer. Modulating on a setpoint
boiler temp is not the same load compensation compensation.

The Savastat does load compensation control of a boiler by switching in and
and out the burner. It is not that cheap and I would go for the Danfoss BEM
5000 as a weather compensator has feed forward control. Both have
anti-cycle control.

John Stumbles wrote:
On Sat, 20 May 2006 02:44:58 -0700, wrote:

... we are planning on putting the new boiler and DHW tank in
the loft.

Following research on google we have decided that an indirect Pandora
heatbank best fits our DHW needs
...
The Pandora I have initially specified is 180l / 100kw / inlcuding two
2 port valves (S plan) that would serve heating/DHW.

That's going to be fun to get into your loft!
(and to site safely)

Now the main issue - choosing an appropriate boiler to cater for the
heatbank and also serve the heating (radiator) system. Following
various discussions with my plumber we have calculated our heating
requirements at around 26kw and to err on the side of caution we are
looking at boilers between 28-31kw.

That's an awful lot of heat. How many rooms does your mansion have, to the
nearest dozen? :-)

Have you checked with the whole-house calculations on

http://www.est.org.uk/housingbuildin.../boilersizing/

and

http://www.idhe.org.uk/calculator.html

(Note that the latter is wrong for mid-floor flats, at least.)

I'd expect to size a boiler at around 10-15kW for normal sized houses.
OTOH if you can afford a Pandora and a MAN then maybe you also have a
house with that sort of heating requirement :-)

Admittedly I have left most of the calculations to the plumber but the
house is probably slightly larger than average, detached and rather
draughty underfloor (1928 built). As DD has pointed out in choosing a
fully modulating boiler it should adjust where necessary...

I could opt for a more economic solution however having reserached the
market there seems to be much of a muchness amongst the cheaper to mid
range boilers and choosing between them seems to be very difficult
however, the Man and a couple of others come highly recommended and do
seem to stand a little above the rest in terms of functionality and
build quality. Horses for courses I guess as they do cost considerably
more as well.

As stated above I am employing an installer to do the actual fitting
and this in itself has it's own complications especially as he would
rather I go for a cheaper more mainstream boiler but I haven't yet
given up hope of converting him.

SWMBO, of course, doesn't understand why I am going to all the trouble
of speccing such a complex and expensive boiler I am still working
on her although as soon as I mention outside weather compensation she
sends out a huge sigh!

wrote in message
oups.com...

John Stumbles wrote:
On Sat, 20 May 2006 02:44:58 -0700, wrote:

... we are planning on putting the new boiler and DHW tank in
the loft.

Following research on google we have decided that an indirect Pandora
heatbank best fits our DHW needs
...
The Pandora I have initially specified is 180l / 100kw / inlcuding two
2 port valves (S plan) that would serve heating/DHW.

That's going to be fun to get into your loft!
(and to site safely)

Now the main issue - choosing an appropriate boiler to cater for the
heatbank and also serve the heating (radiator) system. Following
various discussions with my plumber we have calculated our heating
requirements at around 26kw and to err on the side of caution we are
looking at boilers between 28-31kw.

That's an awful lot of heat. How many rooms does your mansion have, to
the
nearest dozen? :-)

Have you checked with the whole-house calculations on

http://www.est.org.uk/housingbuildin.../boilersizing/

and

http://www.idhe.org.uk/calculator.html

(Note that the latter is wrong for mid-floor flats, at least.)

I'd expect to size a boiler at around 10-15kW for normal sized houses.
OTOH if you can afford a Pandora and a MAN then maybe you also have a
house with that sort of heating requirement :-)

Admittedly I have left most of the calculations to the plumber but the
house is probably slightly larger than average, detached and rather
draughty underfloor (1928 built). As DD has pointed out in choosing a
fully modulating boiler it should adjust where necessary...

I could opt for a more economic solution however having reserached the
market there seems to be much of a muchness amongst the cheaper to mid
range boilers and choosing between them seems to be very difficult
however, the Man and a couple of others come highly recommended and do
seem to stand a little above the rest in terms of functionality and
build quality. Horses for courses I guess as they do cost considerably
more as well.

As stated above I am employing an installer to do the actual fitting
and this in itself has it's own complications especially as he would
rather I go for a cheaper more mainstream boiler but I haven't yet
given up hope of converting him.

SWMBO, of course, doesn't understand why I am going to all the trouble
of speccing such a complex and expensive boiler I am still working
on her although as soon as I mention outside weather compensation she
sends out a huge sigh!

Just say it's far more reliable and very cheap to run. That's all they need
to know.

As regards the plumber, just lay down the specs and say deliver, what he
thinks is irrelevant. When it comes to finer points of heating most haven't
much of a clue, just slamming in cheapish boilers in unbalanced systems.