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Posted by HeatPro on December 15, 2005 at 19:52:09:
In Reply to: Re: Energy Savings 101- Electric vs. Steam? posted by J.C. on December 15, 2005 at 19:35:34:
Reduction of burner input has a smaller effect upon an oil or power gas burner efficiency because the air input is tuned to the nozzle size for efficiency and the combustion chamber of such a boiler is a single vessel with exchangers, not individual burner chambers.
A gas boiler usually has several passages above the burners and reducing the input increases air bypassing the burned gas column (secondary air), so may reduce efficiency. Baffling above the heat exchanger can force the gases to dwell in the pasages; but this requires modifying the burner outlet chamber, so can be dangerous. There is not enough gain by modifying the burner input, although slight reductions in gas pressure at the gas valve could make the boiler steam at a slower rate and hold steam longer. But this is not want you want in order to have a fast cut-off so you have lower house temperatures.
In short, a steam system is not the best for achieving what you want. You can settle for the little gain you would get by just lowering the thermostat and using the electric heaters where needed.
The oversizing has let you take the insulation off the downstairs mains to heat the basement somewhat, as there is excess capacity to handle the pipe losses. A boiler closer to the radiation minimum might have left some radiators cold by removing the insulation. However, unless the downstairs is occupied a significant amount of the day, the net result is a rise in the fuel consumption, which is not desirable for savings.