On 04/05/2021 22:13, Tim+ wrote:

We used to have an old bimetallic Honeywell thermostat but it always seemed
wildly inaccurate and slow to switch on or off.

I thought my problems would be solved by going digital with one of these.

https://www.amazon.co.uk/dp/B07YPQRC...ZZEB6SY8BFE7VE

Today however, it was getting uncomfortably warm in our hall. The
thermostat was set to twenty, it was displaying 20.5 and was still calling
for heat ( flame symbol in display).

Shouldnt it have turned itself off at 20 or are digital ones designed to
keep calling for heat for a period after reaching the target temperature?

Tim


Cannot you use the buttons to manually adjust the target temperature to
find at which point the thermostat stops calling for heat? If its
anything like my thermostat the first press of the button will display
the actual target temperature, the second press will then reduce the
target by 1C. At this point leave it for say 30 seconds to see if call
for heat turns off. Repeat with lower temperatures if still calling for
heat.

Or, perhaps it is the function of the proportional bandwidth facility
(setting) on the thermostat that is attempting to modulate the firing of
an older boiler as the temperature reaches the target and the thermostat
tries to be clever to maintain that temperature that is causing the problem

The following thread may give some insight - read to the 9th post in

https://www.diynot.com/diy/threads/h...mostat.313953/






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On 05/05/2021 06:37, alan_m wrote:

The following thread may give some insight - read to the 9th post in

https://www.diynot.com/diy/threads/h...mostat.313953/


The discussion is about the wireless version of the thermostat so
different model number.

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mailto : news {at} admac {dot} myzen {dot} co {dot} uk

alan_m wrote:
On 05/05/2021 06:37, alan_m wrote:

The following thread may give some insight - read to the 9th post in

https://www.diynot.com/diy/threads/h...mostat.313953/


The discussion is about the wireless version of the thermostat so
different model number.


The principle of proportional bandwidth is the same though so still useful.

Tim

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Please don't feed the trolls

alan_m wrote:
On 04/05/2021 22:13, Tim+ wrote:

We used to have an old bimetallic Honeywell thermostat but it always seemed
wildly inaccurate and slow to switch on or off.

I thought my problems would be solved by going digital with one of these.

https://www.amazon.co.uk/dp/B07YPQRC...ZZEB6SY8BFE7VE

Today however, it was getting uncomfortably warm in our hall. The
thermostat was set to twenty, it was displaying 20.5 and was still calling
for heat ( flame symbol in display).

Shouldnt it have turned itself off at 20 or are digital ones designed to
keep calling for heat for a period after reaching the target temperature?

Tim


Cannot you use the buttons to manually adjust the target temperature to
find at which point the thermostat stops calling for heat? If its
anything like my thermostat the first press of the button will display
the actual target temperature, the second press will then reduce the
target by 1C. At this point leave it for say 30 seconds to see if call
for heat turns off. Repeat with lower temperatures if still calling for
heat.

Or, perhaps it is the function of the proportional bandwidth facility
(setting) on the thermostat that is attempting to modulate the firing of
an older boiler as the temperature reaches the target and the thermostat
tries to be clever to maintain that temperature that is causing the problem

The following thread may give some insight - read to the 9th post in

https://www.diynot.com/diy/threads/h...mostat.313953/


Thanks, that was very helpful. Its probably just operating as designed
then. Ive dug out the instructions and see that it is possible adjust the
proportional band width. I might have a fiddle. ;-)

Tim

--
Please don't feed the trolls