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johnnyreno · 11-23-2014, 11:40 AM

THX dave awhile back i didnt even know about the mixing valve until you told me about it. That valve is located on the rear outside of the ah panel under coach behind the wooden carpeted wall where the rear of the aquahot brass valves come out is it the knob with the red and blue sticker on top that show hotter / cooler CORRECT

johnnyreno · 11-23-2014, 11:49 AM

The blower motor starts, which starts the fuel pump.
The motor runs for about 10 – 20 seconds to allow fuel pressure to build up and stabilize.
The fuel solenoid opens (spraying fuel into the burning chamber), the ignition coil starts creating a spark across the electrodes (igniting the fuel that has been sprayed into the burning chamber).
There is a very slight delay. The photocell (that is adjacent to the burning chamber) looks for light from the burning diesel fuel.
If the photocell sees light, everything is good and the burner will continue to run.
If the photocell DOES NOT see light, the fuel solenoid closes and the `diesel' light next to the switch in your coach goes out. The blower continues to run (purge cycle) for about 2-3 minutes to purge unburned diesel (and heat if the unit has been running).
Blower motor shuts down.

As you can see, this is a complicated sequence. If ANY component fails to operate properly, the diesel burner will not operate. This repair and troubleshooting can be difficult. You many need to seek out authorized repair technician. We have some testing equipment that allows us to check out each component involved in the start up sequence separately. We can provide you with qualified RV aqua-hot system repair.

It could be any of the following items that have failed. Fuel pump, solenoid valve, clogged nozzle, ignition coil (+wires + electrodes), or photocell. On the older (non electronic control board) Aqua-hot system, the high limit thermostat. If you had to reset one of the thermostats, it probably was the high limit thermostat. You need to find out what caused your unit to overheat.

johnnyreno · 11-23-2014, 11:55 AM

The post up above is what i found by a repair company from phoenix az. pretty educational.

Gregory0495 · 11-23-2014, 03:54 PM

Try this shut off city water and use tank water and pump. If it works then it probably is because of low water pressure.

Brett & Christine
2014 Aspire 44U
2014 Jeep Cherokee

Steve COH · 11-23-2014, 04:47 PM

Another test would be to turn off the electric element, and see if you get more or less hot water. If the burner is working correctly, it should provide you with continuous hot water. If it isn't hot enough, then it's likely the tempering valve, as others have mentioned. What I don't understand is why the sudden change. The low pressure would affect both sides of the tempering valve, balancing it out, IMHO.