Anti cycling
- Thread starter Grampy
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Likely over simple but it was explained to me in this way, to start with the boiler reduces the flame size as the return water starts to return hot which will happen when either the TRV closes and so the bypass valve lifts, or the fan speed reduces with fan assisted radiators.
At some point the flame can't go any lower so it switches off the boiler, after x minutes the boiler fires up, if the boiler runs for less that y minutes, then x is made bigger, if it runs for more than y minutes it makes x smaller. So the cycle time changes according to the demand.
The problem is we are not told what y minutes is, likely because this is an over simplification of the system, so if we have too many devices without TRV or fan speed control it can stop the boiler software from adjusting the off time when in cycle mode.
The bypass valve is only required when using TRV's with fan assisted radiators the flow is never altered, so each time the boiler fires it has to heat up every radiator, OK in fan assisted radiators the amount of water in the radiator is small but to heat up all the pipes and the radiators will likely take 15 to 20 minutes, where with TRV's and a by-pass valve if the TRV's are closed the hot water will return within minutes as it does not need to circulate around the whole system. So one would expect that the y minutes would need setting by the installer to suit type of radiators used. However I have not seen a method to adjust y.
All I can assume is y is around 20 minutes to allow for when fan assisted radiators are used.
At some point the flame can't go any lower so it switches off the boiler, after x minutes the boiler fires up, if the boiler runs for less that y minutes, then x is made bigger, if it runs for more than y minutes it makes x smaller. So the cycle time changes according to the demand.
The problem is we are not told what y minutes is, likely because this is an over simplification of the system, so if we have too many devices without TRV or fan speed control it can stop the boiler software from adjusting the off time when in cycle mode.
The bypass valve is only required when using TRV's with fan assisted radiators the flow is never altered, so each time the boiler fires it has to heat up every radiator, OK in fan assisted radiators the amount of water in the radiator is small but to heat up all the pipes and the radiators will likely take 15 to 20 minutes, where with TRV's and a by-pass valve if the TRV's are closed the hot water will return within minutes as it does not need to circulate around the whole system. So one would expect that the y minutes would need setting by the installer to suit type of radiators used. However I have not seen a method to adjust y.
All I can assume is y is around 20 minutes to allow for when fan assisted radiators are used.
WTF are you wittering on about?
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Please disregard most of what was in Eric's post. I think he's been sniffing the toilet duck again.
Then please explain what does happen when the heat demand is lower than the minimum that the boiler can modulate down to.
Burner off pump on.
Your point?
Your point?
At what point is the burner turned back on ?. ( demand from programmer/room stat still active )
Is it a timed function or is it determined by the temperature of the returning water.
bit of both (but based on flow) for one manufacturer
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As said. It depends on the boiler and the controls.
There's no point blathering on about x this year that with fan cooled rads. It's pure drivel.
Not all boilers have return sensors. Not all boilers even have flow and return Sensors.
There's no point blathering on about x this year that with fan cooled rads. It's pure drivel.
Not all boilers have return sensors. Not all boilers even have flow and return Sensors.
In simple terms, Anti-cycling mode is the delay in time between the burner switching off when the boiler setpoint has been reached/exceeded and the burner re-lighting, even though the flow temperature may have dropped well below the boiler setpoint in the intervening time.
It's usually built into the boiler controls, and non-adjustable...though some boilers have it as an 'installer level' parameter.
It's usually built into the boiler controls, and non-adjustable...though some boilers have it as an 'installer level' parameter.
Thanks, I believe I do understand what the anticycling mode is.
What I'm trying to understand is what causes or why a boiler enters this state in the first place.
I take it a number of parameters need to exist for the process to start. Is there a simple way to describe it?
FFS's
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