The Tank › Hot Water turns lukewarm quickly
- December 8, 2010 at 6:43 pm #14669
Our water heater started running cold after a brief amount of time. I ran thru every diagnostic I read about.
I had 240V coming in, ohms on upper element checked out, no leak to ground, and 240V to the element. (I turned the upper thermo down) and had the same conditions on the low side. Based on the condition, reading and frustration I replaced the lower thermo and element.
The conditions improved (nice hot water that lasted) for 2 days, now it doesn’t start real hot and run to lukewarm pretty fast. Went to check and the upper tank was heating up. I am confused. Help!December 8, 2010 at 11:40 pm #14671energyexpertParticipant
You did not give ohm readings.
3800 watt element = 15.2 ohms
4500 watt element = 12.8 ohms
5500 watt element = 10.5 ohms
Sounds like your bottom thermostat or element is having a problem.
If lower element is not heating and upper thermostat is set low then you will have lukewarm water which is short lived and you will find the top element heating if you have just taken a draw of water from the WH.
DavidDecember 9, 2010 at 3:11 am #14674
Hello: Did you check out the plumbing? Cross connections , dip tube and recirc line come to mind 😉 Did you feel the hot outlet from the tank? Is it really as cool as the delivered water?
More tests 😕
Yours, LarryDecember 9, 2010 at 8:06 am #14675
David: 4500W upper 15.1 ohms, lower 12.4 ohms
I agreed with you based on the previous conditions we were having (short term hot water) so I replaced both lower thermo and element and the Whole take got nice and hot. We then had 48 hours of piping hot water. Now we have brief hot then run to luke warm.
Larry: No cross connections and since we have hot water for a brief time then lukewarm I would assume dip tube is okay. The hot outlet feels nice and toasty but when we run low on the hot water it does feel around the same temp as what we are getting at multiple faucets around the house.December 9, 2010 at 1:35 pm #14677
Hello: How about checking the lower element again? It sounds as though it might have failed. Is there a lot of sediment in the tank?
Yours, LarryDecember 9, 2010 at 2:26 pm #14678
Larry: update/question- I turned up the upper thermo a bit and we have piping hot water (plenty for 2 average showers) after which I went and checked the upper thermo and element were getting 240V and working great the Lower thermo and element were getting .004V and even after the tank warmed up a bit the only way to get 240V to the lower is to turn the upper thermo dang near off below 100%.
Is it normal for the above to happen or is the upper thermo bad and not sending power to the lower when it should?
Thank you for your thoughts,
GavinDecember 9, 2010 at 4:16 pm #14679
Hello: The upper thermostat should switch power down to the lower when it reaches temperature. It sounds like it does not always switch when it is long since hot enough to do so. If it’s ever been wet, the contacts may have corroded some and now arc and fuse, or stick at times. If you smell any hot Bakelite odor or see any carbon around the thermostat, replace it. Actually, if you can verify that it’s not switching power when it should, replace it. Sticky contacts could cause this intermittent sort of trouble 😕
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