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 Posted: Wed Sep 28th, 2011 06:56 am
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Washoe
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First of all, I'd like to thank all the administrators and experts for providing this excellent resource.

I have a Reliance 501 40 Gal dual 4500 element electric WH. I just moved in to a new place and discovered no hot water. Hit the reset, and it worked fine for a day or so, then would trip off again. This went on for a while, until one day the button wouldn't pop back out, and the heater wouldn't come back on.

Found this website, went to the troubleshooting section, tested the thermostat, determined it to be bad. Replaced the upper thermostat, it worked fine for another day, came home to find water leaking from the drain valve, and it had turned itself off again (landlord said he'd drained and cleaned the sediment from it, and water supposedly looked relatively clean). Capped the valve with a hose washer, cap, and teflon tape which stopped the leak, hit the rest button, and all was fine again until the next morning, and it had kicked itself off again. Initially, pushing the reset button had no effect. Eventually, I was able to get it to start by holding the reset button down for about a minute or so. Worked fine again for about a day (water temp and quantity was perfect), now it turned itself off again and won't start. Tested the elements, and they both appear fine.

 I have 240 volts at the upper limit screws, no voltage at the elements, yet the elements passed the ohm tests, so that would seem to indicate another bad thermostat. The replacement thermostat seems to be a high quality made in the USA unit that should be compatible with my WH, and I made sure wiring was connected properly. It is rated for 208-480 volts. One seemingly minor issue I had while installing the new thermostat was that it is shorter than the old one, and the upper wires won't stretch far enough to allow it to reach the clip, so it is not quite touching the WH body. But it never seemed to overheat the water, so I'm kinda skeptical this caused it to fail.

I believe it to be a '92 model if I am interpreting the serial # correctly, however externally it looks to be in great shape for it's age, no apparent leaks.

This thing is driving me crazy, I've spent countless hours troubleshooting and fixing it, and at this point I feel a nearly 20 year-old WH is not worth the effort and expense when a new one can be bought for $250-$400, but my landlord wants me to try and fix it again.

What could be causing the thermostat to fail?



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 Posted: Wed Sep 28th, 2011 07:23 am
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Washoe
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Ok, just now on a whim I decided to remove the drain spigot cap to see what-if any-effect it might have; the leak seems to have increased since it was capped, and I still couldn't get the WH to turn back on, so I re-capped the spigot...then I noticed the cold water inlet shut-off valve just outside the wall above the WH is now leaking...:shock:...now what?

Last edited on Wed Sep 28th, 2011 08:09 am by Washoe

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 Posted: Wed Sep 28th, 2011 09:01 am
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eleent
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Hello:  A thermostat is likely bad, though it could be an element with a leak to ground (see tanklets).  The lower thermostat is more likely to fail than the upper one as it gets more use and is more likely to get wet.  So, test elements for leakage to ground and see if the lower thermostat can be shut off once the tank is hot. 

About that valve leak, you prolly have a gate valve that's leaking from the valve stem.  If so, you can loosen the packing nut, wrap the stem in lots of teflon and snug up the packing nut.  I've had good luck with that approach. 

Heaters that haven't been paid attention for twenty years tend to take out their frustration on the nearest human :shock:

Yours,  Larry

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 Posted: Wed Sep 28th, 2011 02:25 pm
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Washoe
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Thanks for the reply Larry.

As I said in the first post, both elements tested fine.

Not too worried about the gate valve, just adds insult to injury on top of all the other issues, and I thought it worth noting in case it might have anything to do with the WH not working, or the leaky drain spigot.

I can't test the lower thermostat to see if it turns off when hot because I can't get the WH to turn on either of the elements at all anymore. Last time I was able to get it working I noticed the upper element cycled on first, shut-off, and then the lower element cycled on. Doesn't the upper thermostat have to cycle on first before the lower one?

I've read a few posts where it was suggested that air in the tank could cause the thermostat to fail if it was drained and then filled without "purging" the air before turning it on again. Is this true, and if so could my landlord have fried the upper thermostat if he improperly drained the WH to clean the sediment from it?

Based on all the evidence, it would seem the upper T-stat is bad again.

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 Posted: Wed Sep 28th, 2011 03:59 pm
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energyexpert
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2 element WH operation:
If the tank is cold, the top thermostat sends power to the top element. The top element heats the water above it. When the top thermostat is satisfied, it turns power off to the top element and sends it to the bottom thermostat. The bottom thermostat then sends power as required to the bottom element. This is known as "the quick recovery" feature; you only heat the top of the tank first. This gives you a few gallons of usable hot water quickly. You can heat the whole tank using just the bottom element but it will take 3 to 4 times as long for the whole tank to reach "usable temperature" than if you just heat a few gallons in the top.

If you cannot get the ECO (red button) on the top thermostat to reset, you will have to get another thermostat. And the thermostat cannot sense the tank temperature correctly if it is not pressed against the tank by the retaining clips.

The ECO (red button) tripping usually results from a crack in the element sheath allowing power to continue to flow to ground (and continue heating) after the thermostat opens one leg of power. The element may read "good" with a meter (12.8 ohms). A 200 ohm leak to ground will continue to add 72 watts to the water indefinitely (until the ECO trips).

David

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 Posted: Wed Sep 28th, 2011 06:22 pm
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Washoe
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Thanks energyexpert.

Just when I thought it was completely dead, I hit the ECO button (after countless attempts to get it going) and it started again.  I'm getting 13.7 ohms at both elements. Set both T-stats at 130, checked temp with laser temp gun, top element kicked off at about 130, bottom element cycled on like it should, haven't checked temp at bottom element yet to see whether or not it shuts off at 130. Voltage spiked up to 253-255 briefly, then went back down to 237. Don't know if that is an issue or not. Tightened smaller nut on gate valve stem, seems to have stopped the leak.

I'm still scratching my head over this, but landlords now just want it replaced. I hope problems don't continue with a new WH. :?

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 Posted: Wed Sep 28th, 2011 06:45 pm
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energyexpert
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Since you have a temp gun, verify the lower thermostat cycles off at set point. First thing in the morning before using any hot water use the temp gun on the tank at both thermostats. If both readings are the same and well above set point, you likely have a leaking (electricity) bottom element. If just the top reading is high, you likely have a leaking (electricity) top element.

David

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 Posted: Wed Sep 28th, 2011 09:55 pm
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Washoe
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I think you're onto something there David.

I just got back after being away from for a couple hours, checked the water temps (both elements are off). Bottom was 125-129F, top was 155-159 (higher than the 130-135F set point). I forgot to mention I have got the upper T-stat to rest against the tank by doubling up a piece of insulation over it and holding it in place with the cover.

My landlords aren't on here right now (they live onsite), and based on my conversation with them this morning, I suspect they are going to come home with a new WH.

Appreciate all the great advice, I'll keep you posted as to the situation.

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