What defines a "Cycle"

Rob23

Hello. I'm new to the forum, but have used it to get some great information on my Buderus G115 WS/5 oil fired boiler.
I'm a little confused as to what defines "short cycling".
Some people seem to refer to only the time the burner is firing as a "cycle".
Others refer to a "cycle" as the time it takes to fire, turn off, and then turn back on.

In my case, with 4 out of 5 zones (circ pumps) calling for heat with a 25 degree outdoor temp day, the burner fires for about 5 minutes, and then shuts off for approx 15-16 minutes. Burner fires up at a boiler temp of 114 and shuts off at about 140.
So the burner fires about 3-4 times an hour.
House is about 3K sq feet, although 500sq feet is a finished basement that rarely has the thermostat on.

Does that seem acceptable?
Thanks for any feedback.

pecmsg

Cycle
run time + off time. Seeing how it takes almost 15 minutes for everything to stabilize I’d say that’s extremely oversized. 

hot_rod

Burner on for at least 10 minutes is another rule of thumb. The boiler block and flue needs to get above condensing temperatures durning that period.

HVACNUT

Dear Headline, Off, on, off.

pedmec

Short cycling is a very subjective term. Reason being is i could have a properly size cast iron boiler with say 5 zones for example. With only one zone calling i will run so much of a shorter cycle than if all 5 zones are calling for heat. The same thing could be said for colder days compared to milder days. The boiler is obviously not going to run long on the milder days compared to the colder days. There really are no set standards that i'm aware of.

I think you have to be an experienced tech to determine whether it's a problem or not. i'm not saying it's good or bad just that it's not a simple determination. Longer cycles are always better for not only the working parts but for comfort. also helps dry out any condensation formed on start-up.

EdTheHeaterMan

I would describe a Cycle as the start a series of events until that moment just before it reaches the same point in the series when that same series of events will repeat. Similar to this illustration below
Ocasionally called a Motor Cycle or a Bi- Cycle or even a Uni- Cycle.
The Earth also has a Cycle that takes a little over 365 days
I'm not going to mention my wife's cycle.

She prefers a Gold Wing, while I'm a HD kind of guy. What cycle did you think I was talking about?

But you can check it out by clicking on the SPOILER.

hot_rod

5 zones cries out for a modulating boiler, on outdoor reset control.