Put a new sender in yesterday. Still no movement on gauge even after 30 miles!is there a thermostat in it?
Check you have electrical continuity and that the guage does work by shorting out the wire from the sender to earth
This should show maximum on the guage with ignition on, but proves all is working
Do you have warm air fron interior vents?
Are radiator pipes warm / hot?
The thermostat keeps the engine warm, holding back the water in the block until it gets up to temp then it lets it go to the radiator for cooling.The thromostat keeps the system cold