I have an installation where both a T2-C and U1 work, using a RM433 and RP6, at over 100'. The range for the T2-C is really dependent on battery strength, but good for 80' on a partial charge. The distances mentioned are distances from the outside of the cottage/house with the RM433 located inside the house in the basement and the RP6 sitting on top of the equipment rack. The client also has a Linksys wireless router working in this cottage.

So, stating the obvious, there has to be something inside your house that is interfering with the system. Have you tried other RM433 locations within the room?