How short is a short cycle?

Steve M. (new homeowner)

I suspect my boiler may be short cycling. How can I tell for sure?

Ken_8

That depends...

A steam boiler might go one once an hour for 20-40 minutes. A water boiler may go on and off two or three times an hour in moderately cold weather.

But there are a bijillion variables that play out here. Biog house? Liuttle house? Steam? Water? Scorched air? Alaska? Texas? day/night setback 'stat?

Need tons more info before a good answer can be made, but generally, 80% of all boilers are oversized. Of those, 50% are twice what's actually required.



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Steve M. (new homeowner)

Its a steam boiler in NJ

Steve M. (new homeowner)

Its a steam boiler in NJ. 2 story medium house. It only runs for a couple of minutes.

Chuckles_3

> I suspect my boiler may be short cycling. How

> can I tell for sure?



A boiler starts up when the thermostat calls for heat. It then runs until the water heats to the aquastat set point.

Bill Nye_2

To me

To me a short cycle is 20 to 45 seconds. A house I am working in now has this symptom. I suspect a defective Taco powerhead or t-stat. Oil co. has been in a couple of times to fix it. When owner gives up on oil co. efforts, I will fix it for him.

In the mean time it drives me crazy to hear it.!

Fred Harwood

Cycle time

For a matched boiler/burner package, closely matched to the EDR load (15-20% bigger boiler), with several Gorton #2s at the end of the main, 3 to 4 minutes on with 10 to 20 minutes off, you should be able to burn clean at slightly more than 80% efficiency while heating each space evenly. You don't want the boiler to be off so long that the mains and rads go cold, and running for more than about 10 minutes will overheat some rads. The miraculous T87F themostat will let you do this and will track outdoor temperature.

Geno_15

tough to diagnose

over the net. You need to know if it's cycling on the tstat or LWCO. I like to see my steam come nice and slow, 5-10 minutes at first from idle, this gives the condensate time to come back and the chamber to get hot, under a couple of minutes and you could start sooting up.

If it's off on LWCO you got a problem with the steam going out and no condensate coming back, you could crack your boiler, watch the sight glass while running, this won't tell you what's going on inside,{ever see the Weil McLain show?} but if the water goes away call for service right away. So many variables..

If it has a head of steam up and then runs about 3 minutes just to maintain and glass gage looks steady nothing is wrong.