I fully expect that my lack of knowledge of plumbing and heating systems is the problem here, but I hope someone can help find the issue.
My heating system is simple single zone open vent setup in a Y-plan configuration consisting of a Vaillant Ecotec Plus 424 with a VR66 wiring centre (setup in monozone/VR65 mode), Vaillant NTC and a single 3 port valve. It originally had the VSmart controller but that was recently replaced by a VRC 700f, by me, as I want to add the Ambisense TRVs (not looking for an opinion on those!).
The VR66 is wired up in line with the diagrams in the VR66 wiring installation guide (see attached) but I have an issue with the heating. If the room is already above the temperature set in the VRC700 the boiler still fires up and the radiators get warm.
If I set heating to OFF on the control and let the rads cool down and then set the heating back to AUTO at a time when it is programmed to be on, but with the room temp already above the required temp, the boiler goes through the following sequence:
1. S.04 Burner on (at the lowest modulation level)
2. Flow temp rises to 38C
3. S.07 Heating mode: Pump overrun (5 mins)
4. S.08 Heating mode: Anti-cycling time (20 mins)
5. S.00 Heating mode: No heat demanded
6. Flow temp drops to 32C
7. S.46 Comfort protection: min load, loss of flame + S.04 Burner on (min modulation)
8. Flow temp rises to 43C
9. Go back to number 3 and loop round again and again ....
The rooms get very warm eventually and I have to set the heating to OFF on the controller to stop the boiler firing up.
The only thing that I needed to set in the new controller was the system diagram. It indicated an error if I selected anything other than number 1. None of the diagrams seems to correspond to my configuration as they all seem to include VR70/71 wiring centres. The controls brochure states that the controller is compatible with the VR66 in a Y plan config.
I asked Vaillant which diagram I should select and they just sent me a copy of the Basic Diagram Book that I already had.
Sorry for the long-winded post but any help for a amateur would be much appreciated.
My heating system is simple single zone open vent setup in a Y-plan configuration consisting of a Vaillant Ecotec Plus 424 with a VR66 wiring centre (setup in monozone/VR65 mode), Vaillant NTC and a single 3 port valve. It originally had the VSmart controller but that was recently replaced by a VRC 700f, by me, as I want to add the Ambisense TRVs (not looking for an opinion on those!).
The VR66 is wired up in line with the diagrams in the VR66 wiring installation guide (see attached) but I have an issue with the heating. If the room is already above the temperature set in the VRC700 the boiler still fires up and the radiators get warm.
If I set heating to OFF on the control and let the rads cool down and then set the heating back to AUTO at a time when it is programmed to be on, but with the room temp already above the required temp, the boiler goes through the following sequence:
1. S.04 Burner on (at the lowest modulation level)
2. Flow temp rises to 38C
3. S.07 Heating mode: Pump overrun (5 mins)
4. S.08 Heating mode: Anti-cycling time (20 mins)
5. S.00 Heating mode: No heat demanded
6. Flow temp drops to 32C
7. S.46 Comfort protection: min load, loss of flame + S.04 Burner on (min modulation)
8. Flow temp rises to 43C
9. Go back to number 3 and loop round again and again ....
The rooms get very warm eventually and I have to set the heating to OFF on the controller to stop the boiler firing up.
The only thing that I needed to set in the new controller was the system diagram. It indicated an error if I selected anything other than number 1. None of the diagrams seems to correspond to my configuration as they all seem to include VR70/71 wiring centres. The controls brochure states that the controller is compatible with the VR66 in a Y plan config.
I asked Vaillant which diagram I should select and they just sent me a copy of the Basic Diagram Book that I already had.
Sorry for the long-winded post but any help for a amateur would be much appreciated.
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