:cool: I installed a Honeywell RTH7400 therm. Today and my heatpump is continuesly cycling on, is there any way to change the temperature differential setting on this unit

See the installer manual that came with the stat or try "Honeywell Thermostats your home expert". Near the bottom of this post

I have read the installation and user manuals, also been to the honeywell website and called the honeywell helpdesk (which apears to be in iraq from the help I recieved) and there is no mention of temp. differential or cycles per hour. Please help!

Here is a link to your stat at Honeywell.

Default - Honeywell Environmental And Combustion Controls

Type in you model number at the bottom right.

Your answer is under cycle rate in the install manual.