Vaillant boiler has the following heating modes;
S0 No heat demand
S1 Fan running
S2 water pump running
S3 Ignition Seq
S4 Burner ignited
S5 Fan and pump running
S6 Fan over run
S7 Pump over run
S8 Anti cycling mode
Just had my central heating system;
1) Changed from open vent to sealed, pressure vessel fitted
2) Power flushed
3) There was no permanent flow-return connection, this was required at the last radiator e.g. if all rads are off or not fully open then there is a permanent connection which ensures the pump has no restriction. This was the theory. It helped the power flush machine circulate properly.
4) Replace the old pump to a GroundFos Alpha2. Set to max speed (3x).
Now I have notice the following behaviour on the first cycle;
S3 is about 5 seconds
S4 is about 1 min
S5 is about 10 seconds
S7 is about 2 mins
S8 is about 5 mins (then goes back to S3)
On subsequent cycles it stay in S4 for about 20 seconds. The remaining steps are similar.
Hence, it takes a long time for the last radiator to heat up, at least 1Hr. I have got about 9-10rads. I can't remember this boiler behaviour in my old open vent system.
I sealed the system so the last few rads heat up faster. Made no difference!
Is this correct behaviour for a sealed system? I have not changed the default Vaillant settings.
Why does the burner turn OFF quickly?
What tells the boiler to jump from S8 back to S3?
Please advise.
S0 No heat demand
S1 Fan running
S2 water pump running
S3 Ignition Seq
S4 Burner ignited
S5 Fan and pump running
S6 Fan over run
S7 Pump over run
S8 Anti cycling mode
Just had my central heating system;
1) Changed from open vent to sealed, pressure vessel fitted
2) Power flushed
3) There was no permanent flow-return connection, this was required at the last radiator e.g. if all rads are off or not fully open then there is a permanent connection which ensures the pump has no restriction. This was the theory. It helped the power flush machine circulate properly.
4) Replace the old pump to a GroundFos Alpha2. Set to max speed (3x).
Now I have notice the following behaviour on the first cycle;
S3 is about 5 seconds
S4 is about 1 min
S5 is about 10 seconds
S7 is about 2 mins
S8 is about 5 mins (then goes back to S3)
On subsequent cycles it stay in S4 for about 20 seconds. The remaining steps are similar.
Hence, it takes a long time for the last radiator to heat up, at least 1Hr. I have got about 9-10rads. I can't remember this boiler behaviour in my old open vent system.
I sealed the system so the last few rads heat up faster. Made no difference!
Is this correct behaviour for a sealed system? I have not changed the default Vaillant settings.
Why does the burner turn OFF quickly?
What tells the boiler to jump from S8 back to S3?
Please advise.
