Probably much covered but a fresh issue for me:-)

Viessman modulating system boiler. Reasonably well insulated house.

Underfloor heating controlled by 10 (yes 10) thermostats and DHW given
priority.

In the excitement of moving house, I hadn't given much thought to time
clock settings and left 24 hour operation selected. With the relatively
warm Winter weather I have realised that the boiler spends most of the
burn time on the lowest of the 5 available settings.

Does this matter? I can cheat by limiting the CH on periods to provide a
bigger load. Any thoughts?
--
Tim Lamb

On Sunday, 29 December 2019 13:01:26 UTC, Tim Lamb wrote:
Probably much covered but a fresh issue for me:-)

Viessman modulating system boiler. Reasonably well insulated house.

Underfloor heating controlled by 10 (yes 10) thermostats and DHW given
priority.

In the excitement of moving house, I hadn't given much thought to time
clock settings and left 24 hour operation selected. With the relatively
warm Winter weather I have realised that the boiler spends most of the
burn time on the lowest of the 5 available settings.

Does this matter? I can cheat by limiting the CH on periods to provide a
bigger load. Any thoughts?
--
Tim Lamb

A constant low burn will be more efficient than on-off-on-off.
If only by eliminating the post and pre burn "purges" of cold air through the boiler.

https://idealboilers.com/support/faq...fan-post-purge

https://www.gobdc.com/purging-airflo...tion-required/

On Sunday, 29 December 2019 13:01:26 UTC, Tim Lamb wrote:
Probably much covered but a fresh issue for me:-)

Viessman modulating system boiler. Reasonably well insulated house.

Underfloor heating controlled by 10 (yes 10) thermostats and DHW given
priority.

In the excitement of moving house, I hadn't given much thought to time
clock settings and left 24 hour operation selected. With the relatively
warm Winter weather I have realised that the boiler spends most of the
burn time on the lowest of the 5 available settings.

Does this matter? I can cheat by limiting the CH on periods to provide a
bigger load. Any thoughts?

Low burn is its most efficient mode.


NT

In message ,
writes
On Sunday, 29 December 2019 13:01:26 UTC, Tim Lamb wrote:
Probably much covered but a fresh issue for me:-)

Viessman modulating system boiler. Reasonably well insulated house.

Underfloor heating controlled by 10 (yes 10) thermostats and DHW given
priority.

In the excitement of moving house, I hadn't given much thought to time
clock settings and left 24 hour operation selected. With the relatively
warm Winter weather I have realised that the boiler spends most of the
burn time on the lowest of the 5 available settings.

Does this matter? I can cheat by limiting the CH on periods to provide a
bigger load. Any thoughts?

Low burn is its most efficient mode.

Yes but:-)

24 hours in low burn at X% or say 5 hours at Y% flat out.

--
Tim Lamb

On 29/12/2019 22:38:46, Tim Lamb wrote:
In message ,
writes
On Sunday, 29 December 2019 13:01:26 UTC, Tim LambÂ* wrote:
Probably much covered but a fresh issue for me:-)

Viessman modulating system boiler. Reasonably well insulated house.

Underfloor heating controlled by 10 (yes 10) thermostats and DHW given
priority.

In the excitement of moving house, I hadn't given much thought to time
clock settings and left 24 hour operation selected. With the relatively
warm Winter weather I have realised that the boiler spends most of the
burn time on the lowest of the 5 available settings.

Does this matter? I can cheat by limiting the CH on periods to provide a
bigger load. Any thoughts?

Low burn is its most efficient mode.

Yes but:-)

24 hours in low burn at X%Â* or say 5 hoursÂ* at Y% flat out.

Assuming the same excess O2 in flue gasses in each case and the same
flow return temperature, the former, as the heat exchanger will be more
efficient with the slower traversal of flue gasses.

That does depend on a good modulating burner.

On Sunday, 29 December 2019 22:42:41 UTC, Tim Lamb wrote:
In message ,
tabbypurr writes
On Sunday, 29 December 2019 13:01:26 UTC, Tim Lamb wrote:

Probably much covered but a fresh issue for me:-)

Viessman modulating system boiler. Reasonably well insulated house.

Underfloor heating controlled by 10 (yes 10) thermostats and DHW given
priority.

In the excitement of moving house, I hadn't given much thought to time
clock settings and left 24 hour operation selected. With the relatively
warm Winter weather I have realised that the boiler spends most of the
burn time on the lowest of the 5 available settings.

Does this matter? I can cheat by limiting the CH on periods to provide a
bigger load. Any thoughts?

Low burn is its most efficient mode.

Yes but:-)

24 hours in low burn at X% or say 5 hours at Y% flat out.

Sure, a house takes longer to heat up from cold. What point were you making?

In message ,
writes
On Sunday, 29 December 2019 22:42:41 UTC, Tim Lamb wrote:
In message ,
tabbypurr writes
On Sunday, 29 December 2019 13:01:26 UTC, Tim Lamb wrote:

Probably much covered but a fresh issue for me:-)

Viessman modulating system boiler. Reasonably well insulated house.

Underfloor heating controlled by 10 (yes 10) thermostats and DHW given
priority.

In the excitement of moving house, I hadn't given much thought to time
clock settings and left 24 hour operation selected. With the relatively
warm Winter weather I have realised that the boiler spends most of the
burn time on the lowest of the 5 available settings.

Does this matter? I can cheat by limiting the CH on periods to provide a
bigger load. Any thoughts?

Low burn is its most efficient mode.

Yes but:-)

24 hours in low burn at X% or say 5 hours at Y% flat out.

Sure, a house takes longer to heat up from cold. What point were you making?

From a total gas consumption POV I was wondering if running a boiler for
long periods at low output/high efficiency is better than drawing the
same total heat output but over a shorter period.

Off must use less gas:-) The house will be kept heated 24 hours anyway.

--
Tim Lamb

Low burn is its most efficient mode.


From a total gas consumption POV I was wondering if running a boiler
for long periods at low output/high efficiency is better than drawing
the same total heat output but over a shorter period.

Off must use less gas:-) The house will be kept heated 24 hours anyway.


Surely, that's what 'most efficient' means? I know nothing about boiler
efficiency. This is purely a semantic point.

On Monday, 30 December 2019 09:27:45 UTC, Tim Lamb wrote:
In message ,
tabbypurr writes
On Sunday, 29 December 2019 22:42:41 UTC, Tim Lamb wrote:
In message ,
tabbypurr writes
On Sunday, 29 December 2019 13:01:26 UTC, Tim Lamb wrote:

Probably much covered but a fresh issue for me:-)

Viessman modulating system boiler. Reasonably well insulated house.

Underfloor heating controlled by 10 (yes 10) thermostats and DHW given
priority.

In the excitement of moving house, I hadn't given much thought to time
clock settings and left 24 hour operation selected. With the relatively
warm Winter weather I have realised that the boiler spends most of the
burn time on the lowest of the 5 available settings.

Does this matter? I can cheat by limiting the CH on periods to provide a
bigger load. Any thoughts?

Low burn is its most efficient mode.

Yes but:-)

24 hours in low burn at X% or say 5 hours at Y% flat out.

Sure, a house takes longer to heat up from cold. What point were you making?

From a total gas consumption POV I was wondering if running a boiler for
long periods at low output/high efficiency is better than drawing the
same total heat output but over a shorter period.

sounds like someone isn't grasping efficiency

Off must use less gas:-) The house will be kept heated 24 hours anyway.