My home has two 40 gallon gas-heated water heaters and since we figured
we need just one for our needs, I shut-off gas supply to one of the
heaters (should save on gas bills).
Since the 2 heaters are in "tandem", they have a copper pipe for
transferring water from one tank to the other.
I checked the plumbing around both tanks and it impossible for me to
figure out which tank supplies hot water first before it 'reaches in'
to the other tank.
So now, I am at a loss to figure out if I had turned off the right
tank. What if I turned off the "primary" tank, in which case, I would
end up getting water from the secondary tank that is mixed in with cold
water from the "primary tank". This would really make it worse since
the water I would get out of the faucets would always be 'tempered'
with cold water from the tank that I shut-off.
I thought about this for a while and figured that if I shut-off water
supply to (cold, pre-heated water) the tank that I cut the gas supply
to, then I would not have the aforementioned issue. I looked for a
water shut-off valve, but all I could find was a small, green-colored
valve that turns only 90 degrees - open or close, on a pipe that goes
into the tank. This pipe is going in to the tank just above where the
pilot knob is (the water heater is made by Reliance).
So, my question is: is the small, green-colored valve the right water
shut-off valve to cut-off water to the tank? This valve is not
something you can rotate - it is a simple, open/close type that only
turns 90 degrees.