This question centers around setting 'D70' on this boiler, which should give either DHW priority when set at '0' or allow CH and DHW to operate together when set at '1'. However, it does not seem to have any effect, as DHW has priority at either setting. Copied below is an edited copy of an e-mail I sent to Vaillant Technical, which explains the situation more fully. They have not reponded.so have any of you guys had a probem like this?
I have an occurrence (won’t call it a problem but may be it is.) that I hope you can help with.
The boiler is a two year old Vaillant echoTech plus 418, until recently using generic controls in an ‘S’ system, which performed faultlessly using two ancient MOMO valves. I fitted a VRT360f controller, VR65 and VR10 in Unistor to upgrade the system. The valves were replaced with spring return Honywel 2-port 4043H valves. I now find that with ‘d70’ at boiler set to either ‘1’ or ‘0’ (yes I did hold the (i) button for 5 seconds until it stopped flashing) the boiler operates with DHW priority over CH in either case. Both boiler controls are set fully clockwise.
This is what is occurring in practice:-
The CH is programmed to activate ON at 06:30 and the DHW at 07:00.
At 06:30 the CH runs normally at a steady flow rate of 75ºC, as set on the boiler, as long as the room temperature demand setting of 21ºC is not achieved. At 07:00, the DHW demand is made by the VRT360f, signified by the flashing tap symbol on the boiler display, and the boiler flame immediately shuts down. After a short pause, the boiler reignites, then cycles quite rapidly until the set DHW of 60ºC is achieved. When checked physically, by feeling valve leaver resistance, the CH valve is definitely closed and the DHW valve is open whilst the boiler is cycling, irrespective of boiler ‘d70’ setting. During last month, when only DHW was activated, boiler operated normally, heating water as required. The system is operating satisfactorily, with cylinder water maintained at correct temperature. Just don’t understand why DHW seems to shut down CH despite ‘d70’ setting being at ‘1’ and causing the boiler to operate for only short periods (cycling) which it doesn't do when only DHW or CH is demanded via VRT360f. Worried that cycling will shorten the life of the gas valve etc. What do you make of this situation, if anything?
Thank you in anticipation
Peter H Kay.[/i]
I have an occurrence (won’t call it a problem but may be it is.) that I hope you can help with.
The boiler is a two year old Vaillant echoTech plus 418, until recently using generic controls in an ‘S’ system, which performed faultlessly using two ancient MOMO valves. I fitted a VRT360f controller, VR65 and VR10 in Unistor to upgrade the system. The valves were replaced with spring return Honywel 2-port 4043H valves. I now find that with ‘d70’ at boiler set to either ‘1’ or ‘0’ (yes I did hold the (i) button for 5 seconds until it stopped flashing) the boiler operates with DHW priority over CH in either case. Both boiler controls are set fully clockwise.
This is what is occurring in practice:-
The CH is programmed to activate ON at 06:30 and the DHW at 07:00.
At 06:30 the CH runs normally at a steady flow rate of 75ºC, as set on the boiler, as long as the room temperature demand setting of 21ºC is not achieved. At 07:00, the DHW demand is made by the VRT360f, signified by the flashing tap symbol on the boiler display, and the boiler flame immediately shuts down. After a short pause, the boiler reignites, then cycles quite rapidly until the set DHW of 60ºC is achieved. When checked physically, by feeling valve leaver resistance, the CH valve is definitely closed and the DHW valve is open whilst the boiler is cycling, irrespective of boiler ‘d70’ setting. During last month, when only DHW was activated, boiler operated normally, heating water as required. The system is operating satisfactorily, with cylinder water maintained at correct temperature. Just don’t understand why DHW seems to shut down CH despite ‘d70’ setting being at ‘1’ and causing the boiler to operate for only short periods (cycling) which it doesn't do when only DHW or CH is demanded via VRT360f. Worried that cycling will shorten the life of the gas valve etc. What do you make of this situation, if anything?
Thank you in anticipation
Peter H Kay.[/i]