Sorry I have to resurrect this because I'm ****ed as hell at these bull**** "scald safe" faucets in my home.

I recently installed an inline water heater. It's not a high-end brand, Eco-Temp or something like that, we needed a new water heater and this one was priced similar to a 40-gallon tank heater, so we got it. It runs on propane (we do not have natural gas).

Just so you understand how inline water heaters work. When you turn on the hot water anywhere in the house, this thing fires up a propane burner which heats a coil of copper pipe that winds through the unit. As the water flows through, it's heated by the propane. There is no tank - water is heated on-demand as you need it.

I have no idea whether this is a "feature" (or lack of) in my specific inline heater, or if all inline heaters work this way. The problem is the intensity of the burner does not adjust adequately based on flow rate. If you turn the hot on full blast, the water is passing through the flames much more quickly, and doesn't heat up as much. If you turn on the hot water only a little, it passes through the flames much more slowly and you get much hotter water.

What this means is, if I want cooler water, I can't reduce the hot handle - that reduces the quantity of hot water, but increases the temperature of the hot side. I have to INCREASE the cold side to make it cooler, and leave the hot alone.

This is IMPOSSIBLE to do with a single handle faucet. When you turn it towards cold, it is both reducing the hot and increasing the cold, and the net difference ends up being about the same. The more you turn it towards the blue, the hotter the hot water gets, which cancels out the increased supply of cold water. One temp is all you get.

That is, until the hot water is trickling so slowly it reaches 140*F, at which point the safety kicks on at the inline water heater and shuts down everything. Then you're back to cold water no matter how you turn the faucet.

Yes, I've tried adjusting the little valve thingy on the sides of the single-handle faucets to increase the max amount of hot water - makes no difference. And also, about half the faucets in my house, the set screws were so crusty/rusted I either couldn't turn them or broke something trying to get them loose.