Shabbos shower

Question

You have said that it is ok to shower in hot water on shabbos. But you, sir, have no way of knowing if the temparture on my hot water heater is truly set to a temparture that is lower than yad soledes bo. When I put on the hot water in my shower, I can't keep my hand under it for more than an instant. When the toilet flushes, I get scalded again. By reflex I jump out of the way. Isn't that yad soledes bo? True, it might not be, I've never measured the temparture of the water, but you certainly have not been in my basement, checking the water temparture, have you? How can you say for sure that hot scalding water isn't yad soledes bo? I think you should qualify and clarify. I think you should say: If you want to take a shower on shabbos you MUST do one of the following: (a) turn off your hot water heater, which means it'll be a cold shower, or (b) Make certain, using a thermometer, or thermostat, but make certain! that the water in your heater is not being heated to a temparture that is above yad soledes bo (whether its 110 or 120 or 125)