By the way, I'm pretty sure that ABYC code is you shouldn't have any valve on the back of the stove. Theoretically, there should be a continuous run of pipe or hose right to the stove. As someone else said, I would guess the leak is in the stove itself, and the most likely place is one of the burners. That would be easy enough to test by taking the hose off the stove, capping, and see what happens at the pressure gauge.