1/2 in. Toilet Anti-Sweat Valve

A:  No the specification sheet, a PDF of which can be found under the header "Info and Guides" on the Home Depot product listing page, indicates 125 PSI. These questions are routed to the supplier so I can confirm 125 PSI is correct. What I can't tell you is why the made the 15PSI typo. Thank you for bringing it to my attention as I will have them fix it. In answer to your question what home has water pressure that low? Not one I would want to live it.

A:  It has a check valve

A:  You are correct, Because you are creating a cross connection between hot and cold you could theoretically create enough of a pressure drop somewhere else on the system that hot water migrates into the cold or vise versa. I have seen this many times with water re-circulation systems. The system works great until the home owner goes to fill a large whirlpool tub. The tub fill dumps so much water that the path of least resistance is not just water coming up the hot line, cold water also begins to run up the return line tempering the water coming out of the spout. The solution is a check valve. I have never seen or heard of this happening with a toilet tempering valve but i would not deny that it is possible. It is not the type of back flow that would keep me up night because both the hot and cold side are potable.

A:  One of the reasons this valve is expensive is because it has two check valves built in. See the specification sheet link above for a cut-away view. The two springs are holding the check valves closed while the unit is idle. If the water pressure on the inlet side is higher than the outlet side the check valve will open. If the water pressure on the outlet side is higher or equal to the inlet side it will stay closed. Over time the check valves will fail. You will be alerted to the failure by hot water invading the cold water or vice versa at a sink for instance. Repair is to replace the whole unit.

A:  No it does not have a check valve or back flow prevention devise built in. However there should be one in the ballcock of the toilet it supplies unless it is extremely old

A:  No, it does not have a built-in check valve.

A:  Yes it is. Keep in mind you are not trying to make the water hot. That will cause the increased growth of nasty stuff. Instead you are just trying to increase the temperature of the water to room temperature. That way the formation of condensation on a the tank will be greatly reduced.

A:  Very easy to adjust. Turn it clockwise to lower the temp. It may take some tweaking to get the temp right. The water coming into the tank should be room temp, not warm or cold.

A:  Yes as the thread is backed out the water will get warmer