Worcester Bosch Anti Fast Cycling

[John Carroll]

Some one asked me some time ago  to have a look at this and explain how it works, I got a lot of info from  another site and I think this is how it works.

It uses time and temperature vs time only in most fairly simple anti fast cycling methods, Vaillant use a table of time+target temp.

 

WB 2.3B   Anti Fast Cycle Time, (settable) 3 to 45 minutes, default 5 minutes.

      2.3.C   Anti Fast Cycle Flow Temperature Hysteresis, (settable)  2C to 15C, default 6C

 

His is set, 12 minutes and 7C.

The "anti fast cycle time" is actually the last  running time of the burner, if the last running time was 12 minutes or more then the boiler will refire when the flow temperature falls to target temp - 7C, if the boiler then runs for say only 5 minutes before the next burner cut then it will not look at the flow temperature for (12-5), 7 minutes, if the flow temperature has then fallen to target temp - 7C (or more) then the burner will refire. This would seem to indicate that the minimum anti cycle time is the time taken for the flow temperature to fall to the target flow temp - 7C.

 

       

Edited 14 hours ago by John Carroll

[JohnMo]

But this mechanism is to protect the boiler, nothing more nothing less.  Short cycling is just a quick way to empty your bank balance. You heat the boiler, pipework and a load of energy goes out the flue and maybe you still have a cold house.

 

If you boiler is in that mode, you maybe have way to many zone, badly set up heating system, or another issue, or all the above.