My Rinnai Tankless gas water heater makes a loud / deep horn vibrating sound when I turn on the hot water. It last a few seconds then stops. The hot water heater works perfect other than the loud sound. It usually happens first thing in the morning with the first need for hot water. In the winter months, it happens almost evertime you turn on the hot water. Almost never happens in the summer.

SOURCE: Rheem small 6 gallon water heater vibration/noise

If the water heater is working fine than I would not worry about the function of the water heater. What the problem may be is that some of your WATER LINES HAVE MOVED, AS THEY WERE NOT SECURED PROPERLY. The sound you may have heard was the Copper or PVC(Plastic) lines just getting back comfortable. I Suggest checking that your water lines are secured about every 3 or 4 feet with the proper ancjhor....Metal for metal pipe, copper for copper pipe, etc. Sometime as in my house, pipes are run through a hole drilled through a stud or a piece of wood, usually when hot water is run through this pipe. You can here an expansion of the water line interacting with the pipe expanding, if the hole in the wood was not drilled big enough......Experience of remodeling a very old house.......Joe

SOURCE: No hot water

The code # 11 is a code that warns of "no ignition" and the causes of this error code are too many to list. I would suggest that a qualified tech. perform a diagnostic test and repair.

This is not a task for the "do it yourselfer"

snap101

• 117 Answers
• Posted on Jul 29, 2009

SOURCE: this things beeping and flashing 12 everytime we

check the error codes on it by pressing the on off button for 2 seconds then while holding the on/off button press the up button this should display the last 9 error codes let me know what they are

SOURCE: I have a Rinnai tankless gas water heater and this

Error 12 is failed ignition - this can be caused by many things, but normally a low gas pressure, or no gas pressure upon ignition.
Try turning the hot tap on very slowly till till the control shows burner is lit. Then turn it on faster. If it stays going with no error, you might have a faulty regulator, not opening fast enough to meet demand. Especially common with lpg models,a lot rarer on natural gas.

Steven Foerst

• 52 Answers
• Posted on Apr 05, 2010

SOURCE: which circulating pumps works on tankless water heaters

Laing UCT-909-TANKLESS UltraCirc Tankless Water Recirculating Pump

This is designed to maintain the proper flow to fire the heater. Please be sure the pressure in the house is at least 5 psi over the minimum required for your unit.