The water temperature in my shower is hard to control, so I bought a shower shut-off valve hoping to be able to conserve water by setting the temperature at the beginning of my shower and to temporarily turn it off while I lather myself with soap. I installed the valve between the handheld showerhead and the shower hose.
I've noticed the following:
- I set the shower faucet to my desired temperature and wait for the water to reach that temperature.
- I close the shut-off valve.
- I wait a few minutes.
- I re-open the shut-off valve.
- First there is a small amount of cold water. (I assume that this is water in the shower hose that cooled off.)
- Then there are a few seconds of very hot water.
- Finally the water is at my original desired temperature.
Why are there a few seconds of very hot water?
I've considered that maybe this was a psychological effect: perhaps I got cold from being soaking wet while the water was off, and the water only seemed hotter? I haven't formally measured the temperature, but I have tried reopening the shut-off valve while dry, and the water is still initially very hot, so I don't think it's an illusion.
(I don't think we have a water circulation pump since we usually need to let water from the hot tap flow for a while before hot water actually comes out.)