About four months ago, I replaced one of the elements on my water
heater (240V / 4500W per element - heater's about 5 or 6 years old).
There are two elements on the heater, and the upper element seemed
fine so I left it alone. Yesterday, the new element failed. I pulled
it out and found a hole blown in the element. This time I replaced
both elements and both thermostats.
Can someone explain some things to me.
1. Why did the new element fail so soon?
2. Why are there two thermostats?
3. Should the lower thermostat be set at a different temperature than
the upper one?
It should be noted that the heater is very difficult to get to. It is
difficult to explain just how hard it is, but it takes about an hour
just to get to the heater. So I want to minimize the number of times
I have to access the heater. The heater is a 6 year system, and it is
around 6 years old. I figured it was a safe bet to replace everything.
Don't know the answer to that one. Bad element? Bad water?
If I remember the explanation correctly (somebody correct me if I'm
wrong), it's a demand thing. Cold water enters the heater at the
bottom of the tank, hot water exits at the top. Normally in times of
low demand, the upper thermostat keeps the upper element off and power
is passed to the lower thermostat, which switches the lower element on
and off to maintain the water temperature.
If demand lowers the water temperature at the top of the tank
sufficiently, the upper thermostat switches power to the upper
element, which is closer to the hot water outlet, in order to try to
meet the increased demand. When the upper thermostat shuts off, power
is passed to the lower thermostat again.
I would think you would want them somewhere close to the same
temperature. I don't imagine those bimetallic spring thermostats are
very accurate anyway.
So bottom element failed again.
most likely the tank is slugged up, full of crud....
element cant transfer heat properly, overheats and blows bad area.
when it fails again buy a new tank and replace it.
might consider relocating tank to a easier access location.
is the tank are backfilled with all sorts of junk? thats happened here
rooms packed with debris.
after finally pitching a lot of junk it felt good, and is easier to
find what remains:)
we had so much stuff when we needed something it was easier to go buy
new, which only added to the problem:(
anyhow good luck with your tank
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