ShortCycle

Weitz

Intalled a new steam boiler based on connected load including new addition with new radiators. New addition not built yet so additional rads not yet hooked up. System ran fine until basement pipng was re-insulated. Now boiler short cycles (am guessing becasue it is looking for those not-yet-hooked up rads) Was it a mistake to proceed with the pipe insulation before the new radiators were hooked up? New addition still several months away, so what to do in the meantime?? (Don't want to take insulation back off if can help it)

john_27

Did you check the venting....I had a similar issue, and Noel and Steamhead have helped me and many other regulars on this site....you can use the search function on the wall...insert "short cycle', and have a wealth of help...let us know how you do...John

Weitz_2

I will try the search engine, thank you...In the meantime, does anyone know what the formula or rule of thumb is for when a steam boiler is considered "oversized" for its connected load??
In other words if a boiler is rated for "X" what percentage of "X" should be connected to avoid short cycling? I ask because if I new how much more load I would need to get within acceptable range, I could very easily hook up some temporary additional radiation elsewhere in the house until the new addition is complete. (There are old plugged taps and holes in the floor where radiators have been removed - I could even run a temporary line to a radiator outside on the rear deck if it would improve fuel consumption in the meantime. Does anyone know what that rule of thumb or formula is based on percent of rated capacity??

Unknown

Short Cycle

Yes the boiler runs in a short cycle but it is not short cycling.

You answered your own question by stating that the new boiler is sized for a new connected load, also the insulation on the steam piping can add as much as 20% greater capacity to the boiler.

What I see here is a boiler that currently sized close to two times what is needed to heat the building there fore steam will be produced much faster than it will be used up, hence you boiler operating cycle time is far less.

If this is a problem for you you can derate the burner. If you have an oil job put in a smaller nozzle in the boiler. If you have a gas job ajust the burner down a bit.

Real short cycling is when a boiler shuts down on low water and you can not make enough steam to heat the building properly.

Jake