Wax elements are also used in thermostatic valves for faucets (to keep faucet temperature constant given variable hot and cold mains): <a href="https://rogerdickey.com/the-ideal-faucet/" rel="nofollow">https://rogerdickey.com/the-ideal-faucet/
It doesn't maintain temperature at all; it maintains the hot/cold mix.
The problem is that the hot temp varies widely (and the cold temp varies slightly as you drain the house tubing reservoir and begin drawing ground-temp water).
rogerdickey · · focus · HN ↗
paradox460 · · focus · HN ↗
Push/pull adjusts volume, rotation adjusts hot/cold mix
IAmBroom · · focus · HN ↗
The problem is that the hot temp varies widely (and the cold temp varies slightly as you drain the house tubing reservoir and begin drawing ground-temp water).