I have a TM4 and use it with SPM on domestics and rinse with warm plain water. I have a steempro and no inline heater and it gets me the results I need. I got this because I just did not fancy the sebo duo which I know is widely used, because I thought it a bit light. You have to clean it each time you use it otherwise the crud that comes out of the carpet in the form of the fibres locks in the moisture and it sits on the metal plate underneath and that is what will cause the rusting eventually. Sometimes come up on E Bay.