Interaction of magma with ground or surface water can lead to explosive phreatomagmatic eruptions. Poorly understood questions of this process center on effects of system geometry, length- and time scales, and these necessitate experiments at larger scale than previously conducted in order to investigate the thermohydraulic escalation behavior of rapid heat transfer. Previous experimental work either realized melt-water interaction at similar (meter-) scales, using a thermite-based magma analog in a confining vessel, or on smaller scale using about 0.4kg remelted volcanic rock in an open crucible, with controlled premix and a trigger event created by a low energy air gun pellet (about 5J kinetic energy). The new setup uses 55kg melt for interaction, and the timing and locaiton of the magma-water premix can be controlled on a scale up to 1m. A trigger mechanism is a falling hammer that drives a plunger into the melt (about 28K kinetic energy). Results show intense interaction at relatively low water to magma mass ratio. A video analysis quantifies the rate and amount of melt ejection and compares the results with those using the same melt in the smaller scale setup. Experiments show that on the meter scale intense interaction can start spontaneously without an external trigger if the melt column above the initial mixing location is larger than 0.3m. A dependency of system response on water mass flow rate was not observed.