electric hot water heaters

[Paul Chelew]

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

[gmcbuffalo]

Paul you lost me. How do you know the heaters are putting out 99 and 150. You say you have check the temps coming out to of the PT valves and they are the close to the same. Is that 150 or 99? What about the drain valves, what's the temp there?

[Gil_J]

Paul, I too am a bit confused on how the temperatures were measured. Turn off the water and power to one heater and let the other come to temperature. Turn off the electric to the heater that just got hot and run the water to get rid of the hot water. Turn off the water to the one that got hot and turn on the water and electric to the other. Once that one comes up to temperature measure the temperature. I believe this is the only way to determine the heater's temperature because I don't believe there are any check valves on the hot water side of the heaters. If these come out close to each other you don't have a problem.

It's possible that the water flow rate through the heaters is different enough that when only one is on it may appear it's temperature is low because of the cold water flow coming through the heater that's off.

[otto]

You have all given me the confidence to tackle problems. Our water heater was not working so I checked the thermostat and the heating element. The heating element was bad, replaced it, and suddenly lots of hot water for our first real trip this month! POG is a real source of information and courage for those of us who are not by nature mechanical or fixers. Now as we start our journey the nagging concern of what might break on some lonely road to nowhere is replaced by ' hum, if something happens I might just be able to fix it myself' and the knowledge that there are others who have faced similar problems in the past. The journey is much more fun when it becomes a positive adventure instead of a drive into the void.

Thanks, Otto Rogers

[garyde]

Yes, Another happy POG member! The fact is , these are wonderful machines with many moving parts. Some things I can do myself, other things I know who to call or where to go to get repairs and maintence at the most reasonible cost. All learned right here .

[Paul Chelew]

Gil & Greg:
I just spent 15+ minutes writing a detailed reply to the questions about how this all took place, then hit Post, and it went into cyber space. Don't have the time/patience to try again. Call if you want a verbal description 775)246-9009.

[Paul Chelew]

Gil & Greg: I'll give this another try at Posting a reply. The temps were measured over several days time, with the heaters being both turned off between temp measuring events. The water temps were measured, one heater at a time being turned on, the other one off, with at least a day in between each event to allow the water in the heaters to cool off. The point of measurement for each heater was the outflow from the PT relief valve, which can be manually opened, and which is routed in my coach via a silicone hose about 2' to 3' long, thru a hole in the bottom of the compartment. Water coming out of those hoses was about 150 degrees for each heater/hose, demonstrating that each heater was working properly/the same.
The drain valves in this case were not an accurate source of temp measurement because of the way they are routed, so were not used for measurements.
Hope that clears up an confusion.