Closing off radiators in a one-zone house

[Wet_Boots]

I noticed some radiators have been removed in this re-hab project I'm taking on, and in terms of what heating is actually essential in the short haul, I could shut down some more. Is there a general rule to the numbers of radiators needed to remain 'on' in a steam system? The original ten radiators has become eight, and I would look to have five or less remaining on. Input BTU is 115,000 for a small (1000 - 1200 sq ft) two-story that sits atop a garage. Garage still has one radiator connected (used to have two) and one was disconnected from a top-floor room (no plumbing in the top floor) at the head of the stairs. I would like to use heat tape on exposed copper pipes near the garage ceiling (followed by insulating and enclosing them, to keep cold garage air away) so I can do without having to heat up the garage.

[Furd]

One of the few positive qualities of using steam in a residential heating system is the ability to turn off individual radiators. You can turn them all off if you so desire. The fewer radiators that are "on line" than the system was designed for means that the boiler will cycle on and off much faster. This short cycling IS less efficient than is longer on periods but it is otherwise not harmful.