Gil:
This will be a bit long, but hope it might help. About 1 1/2 years ago, heater # 1 stopped heating to more than about 99 degrees. It used to go to about 150 degrees. Heater #2 continued to heat to about 150. The two are on different legs of the AC system, and the Link 2000 Heart displays have the ability to show amp draws on each leg. Last summer we went to Oregon Motor Coach for other work, plus a request to fix this problem. They assigned a new hire to the heater problem, who, over several days at OMC shop, proceeded to replace the hi temp limit switch, the heater element, and run up about 6, 7 hours of labor, all without solving the problem. When I got home, I called the heater mfr., got their tech help person, was told to check: amp draw (had already done that, no difference between the two heaters); the temp of the water output by manually popping the PT valve and reading the temp at the outflow hose ( did that, both heaters were within a couple of degrees of each other); time from cold to hot shut-off (both were within 4, 5 minutes of each other); amp draw from cold to hot shut-off per heater (both pulled within a couple of amps of each other). Failing to find any discrepancy, they advised that one of the cold water check valves could be allowing cold water into the output line when the hot faucet was opened with heater #1 on line alone. I replaced both check valves, and all of the cone washers in all of the in/out lines at the heaters. No change. After that, I got tired of working on the problem; no one at OMC or Country Coach Corp in OR , or at Atwood Mfg. had any further suggestions. I think the low temp sensor is the problem, but haven't had the patience/time to pull the whole thing apart again and do the work. Any ideas?

Paul