short cycling-basic question about it

Brad White_26

can be subjective, eye of the beholder. I generally take umbrage at any cycle less than two or three minutes burn time. Specifically that is the minimum time it takes to get the combustion gasses stable and in balance, flue passages warmed and maximum combustion efficiency. Otherwise it is like the proverbial 18-wheeler reving up from a stop and breaking four car lengths later. You lose the hardest momentum you can buy.

Each time a boiler fires, there is a spike in CO, flame is not fully formed, O2 is not fully mixed, combustion is not as complete as it could be. This spike lasts various times but usually 2 to 5 seconds, then starts to stabilize to a steady state. Optimum efficiency does not arrive for about two minutes depending on many variables.

That is my short answer.

Modulating fire is great to forestall this. If on-off (Bang-Bang) at 90,000 input, does it not make sense to modulate back and forth between 25,000 and 90,000 to meet a finite and variable setpoint? Heating should be analog, not binary :)

Dan_15

short cycling-basic question about it

Hi
I see talk of short cycling and just have a quick question about it (I think it is a quick question anyway.)

Is there a defination of short cycling, or does it vary based on the burner?
Is it based on how long the burner is on for, or how short of an non-burn time there is between burns? Mainly interested in an oil burner since that is what I have.

Which ever it is, how what is the time that is generally considered to be a short cycle (and is it between burns, or the actual burn time)?

Along these lines, how long does an oil burner need to be burning for to produce an efficient flame.

Thanks!
Barry