Abstract A wireless sensor network consists of a large number of resource-constrained sensor nodes that are self-organized into a multi-hop network. Many sensor networks are deployed in environments where physically collecting previously deployed nodes for the purposes of re-programming them, i.e., updating their software, is either very difficult or infeasible. This gives rise to the need for over-the-air network re-programming for updating sensor nodes in place. The critical service required to enable multi-hop network re-programming is a reliable bulk data dissemination protocol, i.e., a protocol for reliably distributing a large object such as a code image to all the nodes in the network. The main requirements for such protocol are reliability, energy efficiency and low object delivery latency. In this work, we study some existing approaches for reliable bulk data dissemination, and propose new approaches. Specifically, one of our new approaches uses multiple radio channels that are available on current generation sensor nodes to reduce packet collisions and increase propagation rate. Another approach uses a multiple phase core based scheme to reduce energy consumption. We give both simulation results and experiment results to show that our approaches enhance performance by reducing energy consumption during data dissemination and object delivery latency, compared to existing approaches.