I purchased the TS710 as a direct replacement for the TS 7899. I found that it did not clip into the wiring plate of the old model easily so decided to replace the wiring plate with the new one supplied. The wiring positions are all the same and it looks identical. Setting up is straight forward, however switching between different programs is not as simple as the old model.
Easy to fit & easier to set a programme that my old one of a different brand.