Originally Posted by ependydad
If you have a bypass kit and that is open, you're introducing cold water into the stream of water. The bypass valve should be "closed" for normal use.
Originally Posted by f1100turbo
Do they look like this?
Sabre owners united!
As ependydad and Turbs pointed out, your bypass valve needs to be closed. If you have the valve type as shown in Turbo''s pic, it is closed when the valve handle is turned to the position it intersects (crosses) the pipe itself. It is open when it runs perpendicular with the pipe.
Turbos pic shows the valves at the top outlet (hot/red) and bottom inlet (cold/blue) open (perpendicular to the pipe) but the middle bypass valve (red/blue) closed (intersecting the pipe). This is how yours should be if you have the 3 valve system. Even though all the valves are all pointing the same way, the bypass pipe is running vertically, thus the valve is actually pointed different from the two horizontal pipes. The bypass valve needs to be closed.
Another way that cold water can be mixing with hot water, is if you have the outdoor or indoor shower taps turned on at the faucets, but have the handheld shower wand itself turned off (there is a button on the side of the wand). This is something a lot of people forget about, and turn the water off with the wand, but forget to turn the actual taps themselves off.