Is there a more up to date model or brand than the mears m21sp? Mine broke and I need to replace it. What else is compatible and if nothing else is, where can I buy a new m21sp? Thx!

A replacement should be available here:

Chatham Brass Co., Inc (http://www.chathambrass.com/)

Line Voltage (http://www.chathambrass.com/Pages/ProductCategories/10LineVoltageThermostats.htm)

I have a mears m21sp thermostat and want to replace it with a mears programmable thermostat, can you please recommend one that is compatible