I have a Vaillant heat only boiler controlled by an Evohome, installed one month ago and all working perfectly. The Vaillant, when asked provide heat, controls the burner, pump, pump overrun time, minimum burner cycle time, etc. I have three zone valves, and their auxilliary contacts in parallel signal the boiler to provide heat when any valve is fully open. The three zone valves are switched open/shut by three BDR91 relays individually bound to the Evohome and receiving signals from A) internal temperature sensor, B) a remote room temperature sensor Y7RF, and C) a HW cylinder temperature sensor and transmitter ATF500. The Evohome User Guide is not very detailed and I am searching for clarification on some of the System settings.
Minimum On Time: If set to 5 mins what does this control and how will it interact with each of my three BRD91 relays?
Cycle Rate: If set to 6/hr (10 mins), is this the minimum time any of my three BRD91 relays can cycle On to OFF and back ON again?
HWS Valve close delay: If this delays HWS zone valve closing by holding ON my BRD91 relay then boiler will continue provide heat. Since boiler prolongs pump running when firing ceases the should I set this to 0 mins and leave Vaillant to continue pump overrun function?
The HW Cylinder sensor ATF500 has an adjustable differential which is understandable, however the room temperature sensor Y7RF has no mention of differential anywhere. How does Evohome System settings cause the BRD91 relay associated with room temperature sensor Y7RF to cycle on/off. In the old days room thermostats would have an anticipation heater to cycle the heating on/off according to load. How is it done with my Evohome system?
Minimum On Time: If set to 5 mins what does this control and how will it interact with each of my three BRD91 relays?
Cycle Rate: If set to 6/hr (10 mins), is this the minimum time any of my three BRD91 relays can cycle On to OFF and back ON again?
HWS Valve close delay: If this delays HWS zone valve closing by holding ON my BRD91 relay then boiler will continue provide heat. Since boiler prolongs pump running when firing ceases the should I set this to 0 mins and leave Vaillant to continue pump overrun function?
The HW Cylinder sensor ATF500 has an adjustable differential which is understandable, however the room temperature sensor Y7RF has no mention of differential anywhere. How does Evohome System settings cause the BRD91 relay associated with room temperature sensor Y7RF to cycle on/off. In the old days room thermostats would have an anticipation heater to cycle the heating on/off according to load. How is it done with my Evohome system?
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