EvoHome Optimization clarification

[guzzor6]

Hi all,
I'm new in this forum as I just bought EvoHome. I have some questions about optimization settings.

There is three options:
1) optimum start (it seems clear, I could have an early open of the valve to reach target temperature for the hour specified in schedule)
2) optimum end (like the optimum start, but closing early the valve)
3) delayed start: what does it mean?

Another question about optimum start/end. In case I have a schedule like this for the morning (childer room during work day with school):

07:00 -> 21°C
08:30 -> 18°C

I will have 21°C on 7.00 but somewhere after this point valve will close to let temp lowering until 18°C around 8.30? Is this correct?

Is it good to have optimization enabled if I live in flat with a central boiler for the whole flat? I have no my own boiler so I can't start/stop my boiler but my EvoHome can only open/close valve using hot water produced by central boiler in specific time slot.

Many thanks

[mikey8156]

Hi all,
I'm new in this forum as I just bought EvoHome. I have some questions about optimization settings.

There is three options:
1) optimum start (it seems clear, I could have an early open of the valve to reach target temperature for the hour specified in schedule)
2) optimum end (like the optimum start, but closing early the valve)
3) delayed start: what does it mean?

Another question about optimum start/end. In case I have a schedule like this for the morning (childer room during work day with school):

07:00 -> 21°C
08:30 -> 18°C

I will have 21°C on 7.00 but somewhere after this point valve will close to let temp lowering until 18°C around 8.30? Is this correct?

Is it good to have optimization enabled if I live in flat with a central boiler for the whole flat? I have no my own boiler so I can't start/stop my boiler but my EvoHome can only open/close valve using hot water produced by central boiler in specific time slot.

Many thanks

Not sure what delayed start does. The temperature will be held constant from 7.00 to 8.30 at 21C then at 8.30 the set point is set to 18C, the room will cool down to that temperature.

[guzzor6]

Thank you for your reply, Mikey. But I have one more question. What is not clear for me is how optimum start & stop work together.
If I have that contraints:
07:00 -> 21°C
08.30 -> 18°C

for sure the system starts early then 07:00 to give me 21° at 07.00. This is simple.
But what happen before 08.30 if also optimum stop is enabled? It seems a conflict.
Let me better explain: for the scheduling I'm asking to have 21° until 8.30 but, with the optimum stop enabled, I expect the system will close the valve before 8.30 to cool down the room at 18°c for 8.30.
Is this correct?

[mikey8156]

There will be only early switch on if the room temperature is less than the set temperature. Optimum stop will for instance in your situation will turn the heat off at maybe 8.15 assuming you will not feel that the heat has been turned off.

[guzzor6]

There will be only early switch on if the room temperature is less than the set temperature. Optimum stop will for instance in your situation will turn the heat off at maybe 8.15 assuming you will not feel that the heat has been turned off.

Ok, it's clear.
Thanks again Mikey

[DBMandrake]

Thank you for your reply, Mikey. But I have one more question. What is not clear for me is how optimum start & stop work together.
If I have that contraints:
07:00 -> 21°C
08.30 -> 18°C

for sure the system starts early then 07:00 to give me 21° at 07.00. This is simple.
But what happen before 08.30 if also optimum stop is enabled? It seems a conflict.
Let me better explain: for the scheduling I'm asking to have 21° until 8.30 but, with the optimum stop enabled, I expect the system will close the valve before 8.30 to cool down the room at 18°c for 8.30.
Is this correct?

Optimum start is easy to explain it will set the set point for the zone up to the target temperature before the target time such that it will arrive at the target temperature just in time, and ideally no earlier. The startup time for each zone will be different, even if the target temperatures and times are the same as different zones may take different amounts of time to reach their targets based on different starting temperatures and thermal characteristics of the room.

So for example for your 7am 21°C target it might come on at 6am in a particular zone if it thinks this is how long it will take to reach the target given the past learning about how quickly the room can heat up and the starting temperature. During this optimum start period the Evotouch will display the optimisation icon on the screen for the zone and the target temperature will be that of the target it is trying to reach, eg at 6am when it has turned on it will say the target is 21 degrees even though the schedule says 21 degrees at 7. The mobile apps don't show the optimisation icon, only the target temperature that has been brought forward.

Obviously if the room is a long way below the set temperature it will come on much earlier than if it is only slightly below. You can limit the maximum number of hours ahead that it will turn on - default 3 hours.

Optimum stop is a little bit more confusing, but it is described in the documentation. What it does not do, is work like optimum start in reverse. It will not try to make sure your room is down to the next set point in time. Instead it will allow the room to fall to 0.5 degrees below the current set point before the next set point begins. (Obviously only if the next set point is a lower temperature)

So in your example assuming it is up to 21 degrees at 7am, some time between 7am and 8:30am it will close the radiator early such that the temperature drops to 20.5°C by 8:30. It will base this time on the current temperature and how long it has learnt in the past that it takes your room to cool by this much. At the time optimum stop begins the set point will change to the new set point (eg 18 degrees) and the optimisation icon (Euro sign) will appear. Again on the smart phone apps only the new set point will be seen, early.

The effect of current temperature on optimum stop is quite pronounced. For example say that for some reason (maybe a door left open to a cold room) your room is struggling to reach and maintain 21 degrees - if it is at 20.5 degrees or lower during that period then optimum stop will not occur at all - it will keep trying to reach the 21 degree set point right up to 8:30. On the other hand if the room is for some reason over temperature and it can't get it to drop (maybe a door left open to a hotter room) then it will close the radiator and change the set point to 18 really early. I have seen cases where it goes into optimum stop more than an hour in advance because the room is too hot due to the influence of an adjacent hot room leading it to predict that it will take a long time to cool down to current set point minus 0.5 degrees. (In reality with heat from an adjacent room it might never cool down that much in time without the door being closed or the adjacent room itself going off)

Hope that explains it - optimum stop is not there to guarantee the room reaches the next lower target on time, it's there to save energy for the current set point by not maintaining it right up to the very end of the time period when latent heat can keep the room within 0.5 degrees for quite a while with the radiator closed and boiler (other zones permitting) off.

[top brake]

there is a help menu in the evohome parameter settings that explains these features