According to the operators manual:
When starting in cold weather or with a weak battery,
Preheat Glow Plugs (over 32F 20-30 sec. , 32F to 23F 40-60 sec.)
Pull the Decompression knob
Depress the clutch pedal fully
Engage starter
After flywheel reaches full speed (3-5 sec.) push decompression knob back in.
note:
When ambient temp is less than 5F remove battery from tractor and store in warm place until next operation.
Hope this helps, BTW I use an inline coolant heater on my IH3616 and I agree with everyone else they work good.
Let me know if you have any questions about the 7200 I also have the service manual for it.