Official Definition of Short Cycling

JohnG_3

Is there an official heating industry definition of short cycling for steam boilers? Maybe some specification about the minimum firing duration and the minimum period between firings?

Brad White

None that I know of

and the term is subjective. I too would be interested in hearing if there is a definition.

For myself, I would consider short-cycling as "any boiler which shuts down at any point in the combustion cycle prior to achieving steady-state efficiency", as a very minimal standard.

In other words, having a boiler which shut down just as things became stable, would NOT make me happy, but it would be better than coming on for a minute or less then shutting off. Better, I would hope to have the boiler continue in stable operation at least as long as the initial ramp-up and if possible, until the space temperature was satisfied.

To expand on this standard, I would consider short cycling to be any boiler which shuts off prior to making space setpoint. This would of course cover nearly all boilers, especially steam. Steam would be a modest exception though, as these boilers work off of pressure (or on-off on pressure!) until the space temperature is satisfied. Thus steam is harder to define beyond the "establishment of stable combustion" criteria.

Abro

Definition for Short-Cycling

"I would consider short cycling to be any boiler which shuts off prior to making space setpoint."

Any boiler with ODR or hitting any high limits would then be short cycling by that definition.

I think my definition would be pretty basic. Cycling at a higher frequency than necessary to maintain comfort. Where comfort can be seen as the normal set acceptable space temperature differential / hysteresis.