Sommersparschaltung when room temperature is over set temperature even when cold outside.

[BrechtM]

Hi,

I'm sorry to write this in English as I am not a native German speaker. This seems like  the only active Viessmann community on the internet.

I have a Vitodens 200-W B2HF in combination with a Vitotrol 200-e and an outdoor temperature sensor.

When I set a desired room temperature in the living room (where vitotrol is located) to 20°, the installation goes to summer eco mode when the room temperature reaches 21°C. The outside temperature is 13 °C.

When I set the desired temperature to 22°C, the installation leaves summer eco mode and works normally again.

I want to warm other rooms like the bathroom even when the living room is warm enough but this is not possible in summer eco mode as the circulation pump is disabled.

Also I don't understand why it enters "summer eco mode" when the outside temperature is 13°C.

Parameter 1396.1 is set to 25 but the outside temperature is much lower so it simply should not enter summer eco mode.

Should I change a setting? Is this a bug?

Is there perhaps a difference in behaviour between temperature profiles T1, T2 and T3?

thanks.

[HerrP]

Hi!

Perhaps it may help understading to take a look at 2426.2. It is written that if room temp exceeds room setpoint + hysteresis the pump gets switched off. I have no idea of hysteresis setting (must be 0 in your case?). It is written that some 'software tool' is required to control the setting as far as I understand...

Two questions:

- 1396.1 refers to heating circuit #2 (1395.1 for #1) - do you have more than one circuit? (may also affect 2426.2)

- do you have access to 1240.0? If so, perhaps a change might cause the pump to continue running... But there is a known bug with 1240...

everything without engagement - I'm totally unexperienced with B2HF 😉

greetings!

Phil

[BrechtM]

Hi HerrP,

thank you for your reply!

• I have only one heating circuit
• I can change 1240.0. It was configured on setting 1: automatic. The other setting is 2 (not 7 like like the manual states) but this made no difference.

I have no access to 2426.2, it is also not mentioned in the manual. I'll see if I somehow can.

I can of course easily "solve" my issue by setting the target temperature at a high value (e.g 25 degrees) so it doesn't switch off but I still don't understand why it is called "summer eco mode" when it is not summer 😉

[HerrP]

>> why it is called "summer eco mode" when it is not summer

I'm afraid this is related to the room temp control option is not really completely thought through...

>> "solve" my issue by setting the target temperature at a high value (e.g 25 degrees)

this would equal to disabling room temp control, wouldn't it?! I bet getting rid of the room temp control option would solve your issue anyway 😉

greeting!

Phil 

[BrechtM]

Thank you for your input!

The vitotrol can influence the supply temperature of the heating water which is a valuable option but in my use case this is not useful as I want other rooms to be heated independently from the room where the thermostat is located. So you are right simply removing the vitotrol would perhaps keep the circulation pump running 🙂

I was hoping the vitodens would modulate its burner and circulation pump to allow continuous circulation of water at a low level of energy consumption (by lowering its supply temperature when the set temperature is reached) but not shut it off completely.

If the circulation pump is shut off, the vitodens has no way of detecting other rooms request heat.

I suppose I'll have to play with time programming and choosing the right temperature for the three levels (reduced, normal and comfort) to suit my needs. And a shut off circulation pump is still more economic than one running at a low level, off course.

[AleksB]

I have same setup and same behaviour in Heating Circuit 1 (time program mode). My normal mode setpoint is 22°C. Vitotrol show summer eco mode (vito vicare shows summer 🙂 when room temp is at or above setpoint. While in eco mode, I temporarely increment setpoint to 23 and back to 22, Vitodens resumes normal mode and it keeps that mode even at room temp 22,6°. (Param 933.6 is set to 1, and 933.7 to 8 which is low (also tried with 4)). There must be bug or very unusual correlation curve of param 933.7 to hystereris in PID loop. Local support office was rather ignorat to questions and my case.mails. It would help to get an Viess expert help explaining behaviour or recommend solution. Until then my workaround is shorttime trick to Vitotrol.

Heating Circuit 2 works flawlessly, however only driven by outdoor temp.

Regards,

Aleks