My elderly parents live with me, and they like the house really warm. I, however, have come to hate the heat. I have been dealing with by closing off the floor registers in my room. This has worked for the 7 years my folks have been here. A few days ago my furnace quit working (! ). The tech who came to fix it told my father that the furnace had overheated because my floor registers were closed. I have never heard that before, and I have been doing this for years. Will closing floor registers damage a forced air furnace?

It can. Variable speed Carrier furnaces excepted. If the static pressure that the blower can work against is exceeded, the motor works harder. It really depends on how much of the system is closed off and what the staic pressure reduction is with them closed.

The fix, is to install a bypass damper at the furnace. This is done on zoned systems.