Hot water noise when tap is turned on louder when full on at tap. Atwood MOdel GC104A

Model # please? Does it spark outside when first turned on?

Like a buzzing noise? Check valve where water lines connect at back will make a buzzing noise, if you only hear it when running hot water and not when running cold. Remove and replace it after shutting water off, and draining tank down. Be sure to shut off any hydro to electric element prior to draining.You can buy a replacement check valve, or just put a short 1/2" pipe nipple in there instead and reconnect your line, and refill it. noise should be gone .

Your 2 separate thermostats are pre-set so adjustment isn't possible although you can purchase a hotter thermostat. Normally the complaints I get are that propane is not hot enough, but electric is too hot, so I'm wondering if perhaps you haven't got a valve at by-pass in wrong position, or defective that may be allowing cold to mix with the hot. Make sure any valve in between hot (top line) and cold line (bottom) are all the way in off position. You want flow in to bottom open, and out the top open, and anything else in between, shut off. Have you actually tested a cup of hot water from tap to see what temperature it is? I just don't see both thermostats as being faulty at same time, but?

Cold goes in bottom fitting of water heater, so that valve has to be open, and hot comes out the top, so that has to be open, if there is one there, but any valve in between needs to be closed. There are a few variations so if you can explain where your valves are located in the system more precisely, I can help better. Perhaps you can send a digital picture with reply?

The two switches control the water heater either in the gas or electric mode. The switch with the lights would be for the gas operation, and the switch without lights would be for the electric mode. Prior to operating either switch, make sure the water tank is full of water. Turn your hot water tap on, if water comes out, tank is full. Connect trailer to 110 Volt source, turn circuit breakers on, Place switch without lights to on position. If water does not heat in 45 minutes, Install new heat proble. The gas mode should be repaired by someone that is familiar with that system. Atwood can provide you with a local service center.

I had the same problem and I took out the two shut off/by-pass valves (unscrewed handle and removed cartrige) to find that lime build-up had virtually sealed the lines so that no water flowed!
Cleaned out the lime deposits and reassembled valves and water flowed once again.

Try opening the pressure relief valve (carefully so you don't burn yourself) slightly, and see if water comes out and if it is hot. It sounds like you may have very little if any water in there. Check by-pass valves at back of water heater for proper positioning. Cold should go in the bottom, hot out the top. Make sure there is flow through any valves going into bottom, and any valve at the top.Any valves connected in between the hot and cold should be in the off position. If need be, to test if incoming cold water getting into tank at bottom fitting, shut off water, relieve pressure in system by opening taps until all pressure is gone. then close all taps. Now remove your drain plug, then turn water back on, and water should shoot out the drain plug hole with good pressure within a few seconds and flow steady while water on. If not you have a restriction such as valve in wrong position or faulty, so try moving valve to get better flow out drain plug. If flow out drain is good, then make sure valve at top fitting on back of tank (if any) is also open for good flow . Any other valves should be closed in between those 2 lines. Let me know what you find.

Have you checked your by-pass at rear of water heater to make sure it's in proper position? If it's still in bypass, you will only get cold water from either tap. Cold water goes in bottom, and hot comes out top. Any valves in between those 2 lines need to be off. Let me know what you find, as they use a few different ways to do the by-pass.

Kenny did you change the thermo coupler?

Water level safety shutting down heat source