Hot water heater question

[49erinnc]

50 gallon heater but I've noticed that I'm lucky to take a 10 minute shower before the water starts turning cold. And it's impossible to fill the tub for a bath before the water becomes really cold. Gets cold around 2/3 of the way full.

Water heater is pretty old so yes, I know it could stand replacement but I was hoping to get more mileage out of it. Just curious if this sounds more like a bad element or a thermostat issue? A coworker told me that one of the two heating elements is likely bad and to just replace them both. But I figured there may be some folks here with more experience.

I can tell you that the service report shows that the last thing done to it was a heating element replacement in 1994. I was thinking about draining it today, flushing out any sediment and just popping in two new elements. But I'm not sure if that's the source of my problem. Guess it can't hurt but for a 50 gallon tank, I shouldn't be running out of hot water for one shower.

 

[Rubycon]

Check for thermostats and elements with ohmmeter. Very straightforward procedure.

Most tanks are equipped with a 4.5kW element. The lower one fails more often the the upper. Thermostats also fail frequently. NEVER re-wire so both elements run simultaneously. It will overload the 30A 240V 1ph circuit.

Don't forget the sacrificial magnesium anode. It may be expired. They are usually installed in the top of the tank - it will look like a pipe plug and can be removed easily.

 

[tranceport]

Why would you heat the hot water?

 

[FoBoT]

Originally posted by: 49erinnc
I was thinking about draining it today, flushing out any sediment and just popping in two new elements.

unless you have a wacky model, do it, the elements are cheap enough

don't forget to buy the funky wrench if you don't already have one


the water here has so much soda/whatever in it that i have to flush/replace the elements at least every 18 months in mine
i get a quart or two of white rocks/sediment out of it every time

 

[AnyMal]

With heating element being 12 years old I'm 99% certain that's the culprit. Make sure to replace both of them.

 

[Rubycon]

Originally posted by: tranceport
Why would you heat the hot water?

Hehehe

And you think computer nerds are bad with pronouncing acronyms? Here the water heater is called the "Domestic Hot Water Generator" or DHWG for short - which is pronounced "dog".

So what do we say when there's no hot water?

Dog gone.

:laugh:

 

[jdini76]

its hanging around the wrong people. Tell it to hang out with a better element.

 

[lokiju]

Are you sure it has two, IIRC a lot of older water heaters have only one.

 

[marulee]

Originally posted by: MS Dawn
Check for thermostats and elements with ohmmeter. Very straightforward procedure.

Most tanks are equipped with a 4.5kW element. The lower one fails more often the the upper. Thermostats also fail frequently. NEVER re-wire so both elements run simultaneously. It will overload the 30A 240V 1ph circuit.

Don't forget the sacrificial magnesium anode. It may be expired. They are usually installed in the top of the tank - it will look like a pipe plug and can be removed easily.

Something new for me! =)

 

[49erinnc]

Originally posted by: lokiju
Are you sure it has two, IIRC a lot of older water heaters have only one.

Well, considering that I do get some hot water, it either has two or it's the thermostat. Though, I suppose that even if it had just one element, it could be going bad and not completely shot. I'll have to check when I get home but I want to say that there are two element panels on the side of the tank.

We have really good city water where I'm at so I doubt there is much sediment. I'm hoping it's just a bad element since they're so cheap.

FYI, here are the steps I am assuming I need to take. Please correct me if they're wrong:

1. Kill breaker to hwh
2. Shut off water valve at top of heater.
3. Open pressure valve
4. Hook up garden hose to spigot at bottom and drain.
5. Replace heating elements
6. Turn water valve back on to flush out hwh
7. Shut off spigot, refill hwh and close pressure valve
8. Run faucets in house for a bit to flush out any sediment
9. Flip breaker
10. Enjoy long, hot shower

 

[Paperdoc]

I like your sequence, but the flaw I see is: it is based entirely on knowing before you start that the heating elements are the problem.

IF you are OK with checking a live circuit carefully, do a few other checks first.

1a. Kill breaker to hwh, then open access to terminals on both elements. At each one, inspect for broken connections. Check at thermostat also for bad / broken connections.
1b. Disconnect one lead to each element, and use an ohm meter to measure each element's resistance. You need a decent ohm meter and GOOD contact, because a good element will have a resistance of about 12 ohms only. (That assumes it gets 240 volts and pulls 20 amps - that would deliver 4.8 KW heating power.) If you get one or both VERY high, you know it's dead. Check also resitance from one lead to tank chassis ground - this should be extremely high resistance, in the megohm region.
1c. Reconnect the element leads, make sure nothing is touching, and turn the breaker back on. Use a voltmeter to measure the voltage across each element's leads. With a cold tank, probably only the top one will have full voltage. If one or both are getting only reduced voltage, there may be a bad contact in the thermostat or the wiring.
1d. Then try turning the thermostat 'way down and see if you can force it to switch power to the lower element, then maybe even to turn off the power completely if the tank is "hot enough" to satisfy the reduced thermostat setting. This will check whether the thermostat is the problem. Return the thermostat to normal setting.

Go back to your list at step 1. By now you should know whether the problem is in elements, wiring connections or thermostat, and how to fix it.

 

[Mark R]

Originally posted by: 49erinnc
50 gallon heater but I've noticed that I'm lucky to take a 10 minute shower before the water starts turning cold. And it's impossible to fill the tub for a bath before the water becomes really cold. Gets cold around 2/3 of the way full.

Your bottom heating element isn't working, and only the top element is heating the tank. (Because hot water rises, an element can only heat the water above it).

Check the wiring and element on the bottom heater.

 

[MikeyIs4Dcats]

the expected life of a water heater is around 10 years. I'd recommend replacement. Sooner or later the tank will give way and you will come home to a flooded house.