Weird hot water issue in shower

I'm stumped and I hope someone can provide some explanation/advice. For about a week or so, I've noticed that when I am showering the water keeps getting hotter and hotter. Once I feel it gets hotter, I turn the 'Hot' tap down, then it gets hotter..I turn it down further (and repeat). It also feels that more water is coming out. Not sure if it is my imagination or not..lol :doh:

I tried monitoring the 'HOT' tap, doesn't look like it is moving by itself or anything. Can't really explain why water keeps getting hotter and increased water output.

I've got one of those 130L gas water tank outside. I tested input/relief valves, seems to be functioning correctly. It is approximately 4years old.

Can anyone shed some light on this?

Thanks all :)


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