Rinnai R85 goes cold after approximately 1 min of use.

JRyanT182

The above pictures are the burner and burner housing when I removed it for cleaning. The coils (pictures 2 and 3) are what’s inside and above the burners if you were to look inside and up of the first picture. 

So recently, my hot water heater has been acting up. Little over 14 years old I think just randomly started to Not heat fully. It’ll start off hot and half the burner looks like it just turns off about a Minute into a shower. Most of the time it’ll pick back up after a couple minutes of cold water, but sometimes it won’t even bother And stay cold. I flush the system by using a descaling solution. I replaced the flame rods and igniter. It almost looks like it’s getting water damage on the inside of the burner? I’m not sure what else to do. Any thoughts?

Sol_Brother

Try this: while hot water is running in the shower at your usual rate and the Rinnai is lit, press the up arrow and, holding that down press the On/Off button and then let off both. Sometimes you have to try this a few times to get the timing right but if it works it will display the flow rate in tenths of a gallon per minute. Watch while the shower valve is unchanged and see if the flow rate slowly decreases until the burner ramps down and then goes out. If that is happening it may be a fault in the "water flow control device servo" or the signal that is driving it. The documentation I have does not explain why this might be activated but on one V65 I had to just disconnect it to stop it from slowly closing off the flow for no apparent reason. Here are specs for the R75 version but I think they are different, or not even present, on some other models. Voltages while operating: Red-to-Blue: 11-13VDC; Grey - Brown: 4-6VDC; Grey - Orange: 11-14VDC. Resistance when disconnected: Red - Blue 22-26 Ohms.