What constitutes Short Cycling?

vaporvac

What exactly is short cycling?  My boiler goes on for 1 1/2 minutes, the off for 45 sec., then on again for a couple of minutes.  Is this normal and if not what causes it.  I seem to remember it always being this way.  Thank you.



Colleen

BobC

Is this single pipe steam?

When a boiler initially fires up it takes it a while to come up to steam, 8-15 minutes? As the steam builds the steam mains have to be vented so the steam can travel down the pipes, the radiators should be venting also. If the boiler is only running for a minute or two during the initial firing period you probably have main vent issues, can you tell what kind of main vents you have?



It is normal for most boilers to cycle on and off after the initial burn if it's not frigid outside. There is a control on the boiler (Pressuretrol) that sets the pressure range the boiler operates at, usually from 0.5 to 1.5 PSI. Once all the air vents close pressure will build until the upper pressure limit is reached; then the boiler shuts down, the steam condenses inside the radiators and the boiler starts up again until the thermostat is satisfied.  Are the air vents on your radiators all working? What kind of vents are they?



Tell us what make and model of boiler you have and post some pictures of the boiler and the piping around it from a few different angles. Also take a picture of a sample radiator showing both ends.



Bob

vaporvac

Please see related posts

Thanks Bob for your reply.



Like a dummy I forgot all the other  details  It is a two-pipe gasTrane  vapor vacuum system.  I'll have to post the boiler details later.  I'ts aboult 510,000 useful? Btus whatever that means.  There are two numbers, but the lowest one as I remember it is 510,000 btus.  This question relates to my other main postin, but I didn't want it to be lost in the jumble. 

For the long...

http://www.heatinghelp.com/forum-thread/133806/HW-Convert-or-not-on-Trane-Vapor

and the short of it...

http://www.heatinghelp.com/forum-thread/134354/Vapostat-or-Pressuretrol-Settings

I've added a pdf with the near boiler piping.

I've read your replies on many posts prior and would appreciate you insight into my current system set-up and how to best go about changing it.  thanks.



Colleen

vaporvac

Please see related posts

Thanks Bob for your reply.



Like a dummy I forgot all the other  details  It is a two-pipe gasTrane  vapor vacuum systerm.  I'll have to post the boiler details later.  I'ts aboult 510,000 useful? Btus whatever that means.  There are two numbers, but the lowest one as I remember it is 510,000 btus.  This question relates to my other main postin, but I didn't want it to be lost in the jumble. 

For the long...

http://www.heatinghelp.com/forum-thread/133806/HW-Convert-or-not-on-Trane-Vapor

and the short of it...

http://www.heatinghelp.com/forum-thread/134354/Vapostat-or-Pressuretrol-Settings

I've added a pdf with the near boiler piping.

I've read your replies on many posts prior and would appreciate you insight into my current system set-up and how to best go about changing it.  thanks.



Colleen