The boiler I'm planning to get is a Vaillant ecoTEC system boiler, in
order for it to be in condensing mode most of the time I'm oversizing
radiators a little and using a quick recovery cylinder.
Will this make a difference?
One of my relatives has a Vaillant ecoMAX system boiler and on the
inside of the control flap it advises to set the boiler flow temp to
maximum if it is connected to a thermostat, I thought condensing
boilers should be set as low as possible.
Shall I tell him to ignore this advise?

While far from an expert I believe condensing boilers work more
efficiently at lower temps though of course your lowest temp is
governed by the coldest room or maybe water temp if not seperate and
not enough for a shower or bath. I think that is why they should be
set as low as possible. If you set the boiler to a lower temp with a
thermostat the water may not be hot enough to heat the room. if you
set the Temp to Max there will be enough heat but you will waste gas.
I would set the boiler temp as low as i could get away with, and even
consider changing it from spring/Autumn (little heat needed) and
winter (lots of heat needed) would keep things as efficient as
possible.

In an earlier contribution to this discussion,
405 TD Estate wrote:

While far from an expert I believe condensing boilers work more
efficiently at lower temps though of course your lowest temp is
governed by the coldest room or maybe water temp if not seperate and
not enough for a shower or bath. I think that is why they should be
set as low as possible. If you set the boiler to a lower temp with a
thermostat the water may not be hot enough to heat the room. if you
set the Temp to Max there will be enough heat but you will waste gas.
I would set the boiler temp as low as i could get away with, and even
consider changing it from spring/Autumn (little heat needed) and
winter (lots of heat needed) would keep things as efficient as
possible.

I don't profess to be an expert on condensing boilers, but my understanding
is that many of them will modulate the heat input as necessary by turning
down the flame, depending on the temperature of the return water. This being
the case, the flow temperature will presumably be lower when there is less
heat demand (e.g. in milder weather). If this is so, I'm not exactly sure
what the role is of the boiler stat - but it may perhaps govern the maximum
flow temperature, in which case it would only come into operation
occasionally.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

On Thu, 20 Dec 2007 16:04:19 UTC, "Roger Mills"
wrote:

In an earlier contribution to this discussion,
405 TD Estate wrote:

While far from an expert I believe condensing boilers work more
efficiently at lower temps though of course your lowest temp is
governed by the coldest room or maybe water temp if not seperate and
not enough for a shower or bath. I think that is why they should be
set as low as possible. If you set the boiler to a lower temp with a
thermostat the water may not be hot enough to heat the room. if you
set the Temp to Max there will be enough heat but you will waste gas.
I would set the boiler temp as low as i could get away with, and even
consider changing it from spring/Autumn (little heat needed) and
winter (lots of heat needed) would keep things as efficient as
possible.

I don't profess to be an expert on condensing boilers, but my understanding
is that many of them will modulate the heat input as necessary by turning
down the flame, depending on the temperature of the return water. This being
the case, the flow temperature will presumably be lower when there is less
heat demand (e.g. in milder weather). If this is so, I'm not exactly sure
what the role is of the boiler stat - but it may perhaps govern the maximum
flow temperature, in which case it would only come into operation
occasionally.

My understanding is that it's the flow temperature that's regulated by
the stat. This doesn't need to be as high all the time....and keeping it
lower increases the condensing effect.

But I'm not an expert either!

--
The information contained in this post is copyright the
poster, and specifically may not be published in, or used by
http://www.diybanter.com

On 20 Dec, 16:38, "Bob Eager" wrote:
On Thu, 20 Dec 2007 16:04:19 UTC, "Roger Mills"



wrote:
In an earlier contribution to this discussion,
405 TD Estate wrote:

While far from an expert I believe condensing boilers work more
efficiently at lower temps though of course your lowest temp is
governed by the coldest room or maybe water temp if not seperate and
not enough for a shower or bath. I think that is why they should be
set as low as possible. If you set the boiler to a lower temp with a
thermostat the water may not be hot enough to heat the room. if you
set the Temp to Max there will be enough heat but you will waste gas.
I would set the boiler temp as low as i could get away with, and even
consider changing it from spring/Autumn (little heat needed) and
winter (lots of heat needed) would keep things as efficient as
possible.

I don't profess to be an expert on condensing boilers, but my understanding
is that many of them will modulate the heat input as necessary by turning
down the flame, depending on the temperature of the return water. This being
the case, the flow temperature will presumably be lower when there is less
heat demand (e.g. in milder weather). If this is so, I'm not exactly sure
what the role is of the boiler stat - but it may perhaps govern the maximum
flow temperature, in which case it would only come into operation
occasionally.

My understanding is that it's the flow temperature that's regulated by
the stat. This doesn't need to be as high all the time....and keeping it
lower increases the condensing effect.

But I'm not an expert either!

--
The information contained in this post is copyright the
poster, and specifically may not be published in, or used by
http://www.diybanter.com

Thank you, I think I'll be setting the boiler flow temp as low as I
can get away with. (Hot enough to keep DHW at a decent temperature)

In an earlier contribution to this discussion,
Bob Eager wrote:


My understanding is that it's the flow temperature that's regulated by
the stat. This doesn't need to be as high all the time....and keeping
it lower increases the condensing effect.

But I'm not an expert either!


It's certainly true that the flow temperature of a non-condensing
non-modulating boiler is controlled by the stat - but I'm not sure whether
that applies to modulating condensing boilers.

What's your understanding of how modulation works?

I'm sure Andy Hall will be along soon, and put us all right!
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

On Thu, 20 Dec 2007 17:06:55 UTC, "Roger Mills"
wrote:

In an earlier contribution to this discussion,
Bob Eager wrote:


My understanding is that it's the flow temperature that's regulated by
the stat. This doesn't need to be as high all the time....and keeping
it lower increases the condensing effect.

But I'm not an expert either!


It's certainly true that the flow temperature of a non-condensing
non-modulating boiler is controlled by the stat - but I'm not sure whether
that applies to modulating condensing boilers.

What's your understanding of how modulation works?

That it modulates between 'nothing', and the stat setting...but I still
await others!

--
The information contained in this post is copyright the
poster, and specifically may not be published in, or used by
http://www.diybanter.com

wrote:

The boiler I'm planning to get is a Vaillant ecoTEC system boiler, in
order for it to be in condensing mode most of the time I'm oversizing
radiators a little and using a quick recovery cylinder.
Will this make a difference?

Some - in the coldest weather. The boiler will do a reasonably good job
of keeping the return temp down where it can anyway though by modulating
the heat input.

One of my relatives has a Vaillant ecoMAX system boiler and on the
inside of the control flap it advises to set the boiler flow temp to
maximum if it is connected to a thermostat, I thought condensing
boilers should be set as low as possible.
Shall I tell him to ignore this advise?

Depends on the type of thermostat. If the boiler is the type that
supports a external stat with proportional control, then that makes some
sense. It would in effect leave the internal boiler flow temp control
set at maximum and hence "out of the picture" and the actual flow temp
would be controlled based on the actual heating demand.

If however the external stat is the more typical "on / off" style
device, then the advise in the manual does not seem correct.



--
Cheers,

John.

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

Bob Eager expressed precisely :
On Thu, 20 Dec 2007 17:06:55 UTC, "Roger Mills"
wrote:

In an earlier contribution to this discussion,
Bob Eager wrote:


My understanding is that it's the flow temperature that's regulated by
the stat. This doesn't need to be as high all the time....and keeping
it lower increases the condensing effect.

But I'm not an expert either!


It's certainly true that the flow temperature of a non-condensing
non-modulating boiler is controlled by the stat - but I'm not sure whether
that applies to modulating condensing boilers.

What's your understanding of how modulation works?

That it modulates between 'nothing', and the stat setting...but I still
await others!

My understanding is that the flame size is modulated or adjusted
depending upon the difference between the stat set temperature and the
actual temperature of the water exiting the boiler. The closer the two
temperatures, the less heat input is needed.

--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

On Thu, 20 Dec 2007 03:09:11 -0800, dawoodseed wrote:

The boiler I'm planning to get is a Vaillant ecoTEC system boiler, in
order for it to be in condensing mode most of the time I'm oversizing
radiators a little and using a quick recovery cylinder. Will this make a
difference?
One of my relatives has a Vaillant ecoMAX system boiler and on the
inside of the control flap it advises to set the boiler flow temp to
maximum if it is connected to a thermostat, I thought condensing boilers
should be set as low as possible. Shall I tell him to ignore this
advise?

Sometimes you have to imagine what the instruction writers are driving
at. From their POV if you add another control elsewhere the it is
confusing to some users to have more than control! Therefore they are
suggesting that it should be set to max. That way the external control
can always heat the house even in the worst weather.

The smarter user can override the instructions when they understand all
the implications. If you're one of those you will know what to do.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

On Thu, 20 Dec 2007 19:58:39 UTC, Harry Bloomfield
wrote:

Bob Eager expressed precisely :
On Thu, 20 Dec 2007 17:06:55 UTC, "Roger Mills"
wrote:

In an earlier contribution to this discussion,
Bob Eager wrote:


My understanding is that it's the flow temperature that's regulated by
the stat. This doesn't need to be as high all the time....and keeping
it lower increases the condensing effect.

But I'm not an expert either!


It's certainly true that the flow temperature of a non-condensing
non-modulating boiler is controlled by the stat - but I'm not sure whether
that applies to modulating condensing boilers.

What's your understanding of how modulation works?

That it modulates between 'nothing', and the stat setting...but I still
await others!

My understanding is that the flame size is modulated or adjusted
depending upon the difference between the stat set temperature and the
actual temperature of the water exiting the boiler. The closer the two
temperatures, the less heat input is needed.

That's what I was trying to say - in a kind of inverse way!

--
The information contained in this post is copyright the
poster, and specifically may not be published in, or used by
http://www.diybanter.com

On Thu, 20 Dec 2007 19:40:10 +0000, John Rumm
wrote:

wrote:

The boiler I'm planning to get is a Vaillant ecoTEC system boiler, in
order for it to be in condensing mode most of the time I'm oversizing
radiators a little and using a quick recovery cylinder.
Will this make a difference?

Some - in the coldest weather. The boiler will do a reasonably good job
of keeping the return temp down where it can anyway though by modulating
the heat input.

One of my relatives has a Vaillant ecoMAX system boiler and on the
inside of the control flap it advises to set the boiler flow temp to
maximum if it is connected to a thermostat, I thought condensing
boilers should be set as low as possible.
Shall I tell him to ignore this advise?

Depends on the type of thermostat. If the boiler is the type that
supports a external stat with proportional control, then that makes some
sense. It would in effect leave the internal boiler flow temp control
set at maximum and hence "out of the picture" and the actual flow temp
would be controlled based on the actual heating demand.

If however the external stat is the more typical "on / off" style
device, then the advise in the manual does not seem correct.

I can't see how else it could work in the latter case. I always
believed that condensing boilers modulate down when the return
temperature rises too high (unless a weather compensator is fitted).

Please correct me if I am wrong ;-)

M

Mark wrote:
On Thu, 20 Dec 2007 19:40:10 +0000, John Rumm
wrote:

wrote:

The boiler I'm planning to get is a Vaillant ecoTEC system boiler, in
order for it to be in condensing mode most of the time I'm oversizing
radiators a little and using a quick recovery cylinder.
Will this make a difference?
Some - in the coldest weather. The boiler will do a reasonably good job
of keeping the return temp down where it can anyway though by modulating
the heat input.

One of my relatives has a Vaillant ecoMAX system boiler and on the
inside of the control flap it advises to set the boiler flow temp to
maximum if it is connected to a thermostat, I thought condensing
boilers should be set as low as possible.
Shall I tell him to ignore this advise?
Depends on the type of thermostat. If the boiler is the type that
supports a external stat with proportional control, then that makes some
sense. It would in effect leave the internal boiler flow temp control
set at maximum and hence "out of the picture" and the actual flow temp
would be controlled based on the actual heating demand.

If however the external stat is the more typical "on / off" style
device, then the advise in the manual does not seem correct.

I can't see how else it could work in the latter case. I always
believed that condensing boilers modulate down when the return
temperature rises too high (unless a weather compensator is fitted).

Please correct me if I am wrong ;-)

That is my understanding also... The most logical control setup for a
condenser is treat the internal water temp stat as a maximum limit, and
then modulate for optimal (or at least better) return temperature.

For a non condensing, modulating boiler, maintaining the flow temp at or
near the stat temperature would make as much sense.

This does open up the question of how the boilers are not true "designed
from the ground up" condensers will behave, since they are based on a
re-engineering of an original design.

--
Cheers,

John.

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

On 21 Dec, 13:42, John Rumm wrote:
Mark wrote:
On Thu, 20 Dec 2007 19:40:10 +0000, John Rumm
wrote:

wrote:

The boiler I'm planning to get is a Vaillant ecoTEC system boiler, in
order for it to be in condensing mode most of the time I'm oversizing
radiators a little and using a quick recovery cylinder.
Will this make a difference?
Some - in the coldest weather. The boiler will do a reasonably good job
of keeping the return temp down where it can anyway though by modulating
the heat input.

One of my relatives has a Vaillant ecoMAX system boiler and on the
inside of the control flap it advises to set the boiler flow temp to
maximum if it is connected to a thermostat, I thought condensing
boilers should be set as low as possible.
Shall I tell him to ignore this advise?
Depends on the type of thermostat. If the boiler is the type that
supports a external stat with proportional control, then that makes some
sense. It would in effect leave the internal boiler flow temp control
set at maximum and hence "out of the picture" and the actual flow temp
would be controlled based on the actual heating demand.

If however the external stat is the more typical "on / off" style
device, then the advise in the manual does not seem correct.

I can't see how else it could work in the latter case. I always
believed that condensing boilers modulate down when the return
temperature rises too high (unless a weather compensator is fitted).

Please correct me if I am wrong ;-)

That is my understanding also... The most logical control setup for a
condenser is treat the internal water temp stat as a maximum limit, and
then modulate for optimal (or at least better) return temperature.

For a non condensing, modulating boiler, maintaining the flow temp at or
near the stat temperature would make as much sense.

This does open up the question of how the boilers are not true "designed
from the ground up" condensers will behave, since they are based on a
re-engineering of an original design.

--
Cheers,

John.

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

Thank you for all useful information.