Posted by Harold Kestenholz - Hydronic Network on October 21, 2001 at 11:47:24:
In Reply to: Help calculating new boiler size posted by John on October 20, 2001 at 18:54:20:
An important concept is that you will not know if the boiler is oversized or undersized until you operate the system. Calculating the required input also includes knowing the mass and thickness of the piping and returning condensate. New boilers of the correct input may not have enough water capacity to prevent running out of boiler water on a cycle, so may require a boiler feed tank. Larger pipes than estimated at the factory may have been used. Oversizing is an insurance for performance. The worst scenario for oversizing may be operating the boiler on the pressure switch instead of the thermostat, so a secondary safety lockout pressure switch is in order.
The radiation in this home is there to satisfy a heat loss four times that of a home built to today's standards. To attempt to tweak some extra savings from a steam boiler that is going into the most wasteful heating system one could design today, designed a century ago, is beyond worry. The home is a beautiful example of historical development to be treated as a memory of grand times.