Rinnai HE Series How To Use Manual page 191

Cold Water Sandwich caused by faulty fixture:
1. Have customer explain problem.
2. Turn off hot water ball valve on the Rinnai valve kit at the water heater. This should shut off the
water flow to all hot water fixtures at the location. Turn on a hot water fixture to check and see
if any water continues to flow at that fixture. After roughly two minutes all residual water in the
system should bleed down to no flow at your fixtures. If water continues to flow at any flow rate
you have a faulty fixture, check valve, or a cross over in the plumbing system. Plumber or
contractor must locate faulty fixture and correct bleed over.
3. Ask the customer if the location has a circulating system. If so; isolate to circulation loop from
the plumbing system by means of a shut off valve in the return loop. We are trying to ensure
water is not bypassing the water heater through a faulty check valve in the return loop. After
shutting off the ball valve in the circulating loop, all water flow should stop. If not, you may still
have a faulty fixture.
4. Proceed to all fixtures with single handle levers, shut off the cold water ball valve at each fixture
one at a time. Check flow after shutting off the cold water line at each fixture. If water flow
stops during this process, go back to the last fixture turned off and open the cold water ball
valve. If flow starts back that fixture has a bad diaphragm in it. You can either replace the faulty
fixture insert or install a check valve in the hot water feed to prevent cold water from back
feeding. Notify plumber or contractor of faulty fixture.
5. If location has a mixing valve isolate mixing valve, turn off the cold water feed to that device. If
the water temperature reaches temperature and continues to maintain temperature with the
mixing valve isolated, the problem is in the mixing valve.
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