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

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

"Andy Hall" aka Matt <(E-Mail Removed)> wrote in message
news:0001HW.C094B1A2003E6972F0407500@10.0.0.1...
> On Sat, 20 May 2006 10:44:58 +0100, (E-Mail Removed) wrote
> (in article <(E-Mail Removed). 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 <446f5bc2$0$70924$(E-Mail Removed) ews.net>):

>
> "Andy Hall" aka Matt <(E-Mail Removed)> wrote in message
> news:0001HW.C094B1A2003E6972F0407500@10.0.0.1...
..
>>
>> - 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.

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

"Andy Hall" aka Matt <(E-Mail Removed)> wrote in message
news:0001HW.C0953BC9005ECA89F0407500@10.0.0.1...
> On Sat, 20 May 2006 19:02:49 +0100, Doctor Drivel wrote
> (in article <446f5bc2$0$70924$(E-Mail Removed) ews.net>):
>
>>
>> "Andy Hall" aka Matt <(E-Mail Removed)> wrote in message
>> news:0001HW.C094B1A2003E6972F0407500@10.0.0.1...
> .
>>>
>>> - 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 09:54:42 +0100, (E-Mail Removed) wrote
(in article <(E-Mail Removed). 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
>

On Sun, 21 May 2006 10:08:05 +0100, Doctor Drivel wrote
(in article <44702f2f$0$14760$(E-Mail Removed) ews.net>):

>
> "Andy Hall" aka Matt <(E-Mail Removed)> wrote in message
> news:0001HW.C0953BC9005ECA89F0407500@10.0.0.1...
>> On Sat, 20 May 2006 19:02:49 +0100, Doctor Drivel wrote
>> (in article <446f5bc2$0$70924$(E-Mail Removed) ews.net>):
>>
>>>
>>> "Andy Hall" aka Matt <(E-Mail Removed)> wrote in message
>>> news:0001HW.C094B1A2003E6972F0407500@10.0.0.1...
>> .
>>>>
>>>> - 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" <(E-Mail Removed)> wrote in message
news:0001HW.C0960B7F0086C075F0284500@10.0.0.1...
> On Sun, 21 May 2006 10:08:05 +0100, Doctor Drivel wrote
> (in article <44702f2f$0$14760$(E-Mail Removed) ews.net>):
>
>>
>> "Andy Hall" aka Matt <(E-Mail Removed)> wrote in message
>> news:0001HW.C0953BC9005ECA89F0407500@10.0.0.1...
>>> On Sat, 20 May 2006 19:02:49 +0100, Doctor Drivel wrote
>>> (in article <446f5bc2$0$70924$(E-Mail Removed) ews.net>):
>>>
>>>>
>>>> "Andy Hall" aka Matt <(E-Mail Removed)> wrote in message
>>>> news:0001HW.C094B1A2003E6972F0407500@10.0.0.1...
>>> .
>>>>> - 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 boiler runs up
>> the the max boiler 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 :-) )

You should learn how to describe what it does. :-(

> 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.

On Sun, 21 May 2006 12:41:31 +0100, Doctor Drivel wrote
(in article <4470525d$0$70924$(E-Mail Removed) ews.net>):


>>>>> 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 boiler runs up
>>> the the max boiler 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 :-) )
>
> You should learn how to describe what it does. :-(
>

I was trying to keep it simple so that you would understand.