How should a perfectly configured steam system cycle?

stevenyc_2

HYPOTHETICALLY SPEAKING, let's say that there is an efficiently running steam system where the oil boiler is sized correctly and the mains and rads are vented properly. What kind of cycling pattern should one expect in this situation?

Also (if it's possible to guess), how long should it take for a medium insulated 2000 SF home to raise the thermostat 5 degrees on a day where the outside temperature is 32 F.

In this make believe perfect situation:

...should we expect the boiler to run continuously at 1.5 PSI until the thermostat is satisfied, without cutting out or shutting off on pressure

-or-

...should we expect the boiler to build steam to above 1.5 PSI and shut off and then cut in again at 0.5 PSI. If so, what should we expect to get as far as how long the boiler is off, when it shuts off on pressure, and how long should we expect the boiler to be on, after it cuts back in from low pressure. How many times will the boiler go through this on/off cycle before it satisfies the thermostat.

Thanks!

bigugh_4

WOW!

What a question. How big is the boiler and what is the btu load it is supplying? These are math questions that only an inspection of the premineses could determine. After that what is the occupancy and the infiltration like? In short Exactly twice the time it takes to heat the building 2.5* on the thermostat! Similar to a piece of rope? how long is it? Twice as long as one-half of it!

don_52

Not hypothetical...

Steven,

Our new boiler ( as of last summer ) 358' capacity into
358' radiation, the ONLY time it ever hit operating limit
was at -8 coming out of a 2 deg. setback, without setback
( which I opt not to use ) it's -10. ( design conditions )

During load test every rad was ( scaulding ) hot all the way
across at 2 oz. pressure.

It has been said ( here ) that a steam system properly
done should only cycle on pressure at design conditions.

As you had stated, all things being correct, pickup, picth,
runouts and risers being properly sized, etc.

Perhaps this house being built before the "spanish influenza" had something to do with it.

I did alot of research before we bought and everything
is great.

Hope that helps and happy steaming, db

John S.

bigugh...

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Mike T., Swampeast MO

Vary the atmosphere under which the steam is produced and there's no need to cycle. Otherwise the only perfect steam cycle is no steam cycle.