I recently changed my thermostat and want to check the old one. It's not as easy as a conventional thermostat as you can't see inside so easily, so I poured boiling water into the end expecting it to open the thermostat and allow it to flow through, but it didn't so I'm not sure now if it was faulty or if I'm doing it wrong. Any recommendations on the best way to do it?
Pics below, I poured the water in the top
![IMG_3363.gif IMG_3363.gif](https://www.landyzone.co.uk/data/attachments/237/237354-663c9f0acdd51364de1dd45103416f5b.jpg)
Pics below, I poured the water in the top
![IMG_3360.jpeg IMG_3360.jpeg](https://www.landyzone.co.uk/data/attachments/237/237351-8085d41eef8a8947a1c0e577f412f745.jpg)
![IMG_3362.jpeg IMG_3362.jpeg](https://www.landyzone.co.uk/data/attachments/237/237352-26b3682900d43720e7e9cb2c5a1d854c.jpg)
![IMG_3363.gif IMG_3363.gif](https://www.landyzone.co.uk/data/attachments/237/237354-663c9f0acdd51364de1dd45103416f5b.jpg)