I have several rooms in my house that I don't have to use, so I close them off and shut off the heater registers in those rooms to save energy. However, this causes the remaining registers to become very windy and noisy. I believe the reduction in air flow also increases the furnace output temperature and therefore increases heat loss while the air is traveling in the heating ducts in the crawlspace. Also air is lost due to leakages in the heating ducts -- my crawlspace is warmer than outside by at least 10 degrees.
Is it generally possible to lower the heat output of a furnace? This is what I have (replaced last year):
I see three burners inside. I can either pull out one of the burner, or use the shut-off valve to reduce the gas supply. I imagine removing one burner would be more efficient since the remaining two burners will operate at their designed setting.
But I'm not so sure the blower speed can be change. I don't mind rewiring anything if I know it can be done.