I have a White-Rodgers non-programmable thermostat - Type # 1F89-211. I has a setting for "Emergency"... What is this used for... I looked online... their manual says you use it when you want to bypass the compressor... What is the purpose of bypassing the compressor? -- What does this mean? Is it good to do it or bad?

Thank you.

It might better be labeled auxiliary or back up. While heat pumps are more efficient than resistance heat at higher temperatures, they lose efficiency and capacity as the temperatures drop. It is necessary to call on other heat when the temperature drops. This can be resistance heat strips or other heat such as gas. The thermostats can be programed to switch to the other heat if the heat pump can't keep up or you may need to switch manually. When you switch to emergency heat, it shuts the outside compressor off saving power.

It is best to use the heat pump when it works best and only switch to emergency heat when you need to. You can learn more at https://www.askmehelpdesk.com/heating-air-conditioning/heating-cooling-maintenance-repair-troubleshooting-frequently-asked-questions-58313.html