Abstract: A device for pumping an absorbent solution from the low pressure side of an absorption heat exchange system to the high pressure side of that system without relying on pressure from the low pressure side. The device preferably includes a diaphragm pump disposed in an absorbent fluid pathway to pull absorbent solution from the low pressure side and to push absorbent solution into the high pressure side. The diaphragm of the diaphragm pump is powered by a piston-driven hydraulic pump which pushes and pulls oil into and out of the diaphragm pump. The hydraulic pump preferably has sufficient power to pull absorbent solution from the low pressure side of the heat exchange system without relying on any pressure from the low side. Check valves are used to permit the one-way flow of absorbent solution from the low pressure side to the high pressure side of the system.