Building a heatpipe is not a small undertaking, as I understand it for a heatpipe to work needs to be evacuated, that means all air has to be taken out and create a vacuum. This you will find rather difficult to achieve as you may need to freeze the entire assembly, in order to create the vacuum without having all the water boil off.
Also the pump is not necessary, and will interfere with the mechanics of the heatpipe. As I understand it the boiling and condensation process in a heatpipe can take place at supersonic speeds, that's why heatpipes are up to 1000 times more efficient transferring heat than any known metal.
If you would like to see the experiments of someone who tried to build some heatpipes, you can do so
here