The water-powered noria uses the same principle as the Persian wheel and therefore also needs to be of larger diameter than the pumping head, which either limits it to very low lift pumping or requires very large, cumbersome and expensive construction. Small, low-lift norias, used in Thailand and China, are very inexpensive while much larger norias are used in Vietnam and Syria. Some of the largest in Syria exceed 10m in diameter, but in relation to their size they tend to be unproductive compared with more modern pumping systems.
==Construction, operations and maintenance==
====Assembling a water wheel====
* Parts of the wheel were first made up in the Blair Laboratories. They were then taken to the irrigation canal at Mazowe and assembled. The wheel was made up mostly of plywood and pine beams. The axle was made from 75mm steel pipe, reduced through reducing sockets to 50mm pipe. The axle was mounted through two sealed ball bearings mounted on the two brick built supports at the side of the canal.
* Wheel upright and spiral tube fitted. About 35 meters of 50mm polyethylene pipe were coiled on each side of the pump. The pipes were threaded through holes made in the paddles. The two water collectors were made of 150mm PVC pipe, each about one metre long. The ends of the innermost coils were connected to the axle through polyethylene elbows.
* Straddling the canal. The brick mounts for the bearings had already been made.
* The wheel is mounted. Note the two pipes from the coils going into the axle. This method of linking the pipes to the hollow axle with a galvanised steel cross was not successful. The threads in the pipe were weak points and could not take the strain under the weight of the wheel. The axle was replaced with a single 75mm steel pipe and the water was led into it through an entry point nearer the bearing.
* A drum was mounted on an eight metre platform high above the canal. Water and air coming from the coils was led from the axle, through a simple water seal to the vertical pipe which led to the drum. This photo shows the modified water entry point into the axle, to one side.
====Reference manuals, videos, and links====