Water Heater Draining Problem?

[Tarantoga]

I have a water heater that is no less than 18 years old.
I've attempted to drain the thing on a couple of occasions, but not much hot water comes out of it (I'd estimate 5-10 gallons out of a capacity of about 30 gallons), and when I'm done draining it (even after turning on cold water to flush out sediment), I've still got hot water left over (which is apparent when I run the hot water after draining the WH).
Recently I've become more concerned with this state of affairs as my Signficant Other has begun to complain of having insufficient hot water for her bath.

Having read a few of the board messages before posting this message, I saw where somebody removed the heating element to enable a more thorough cleaning of the WH interior. That's what I'm currently set to try, as the element seems to operate properly.

Apart from sediment buildup, why would the WH drain only partially, leaving a substantial supply of hot water left over? I've opened the hot water valves as recommended, but have stopped short of opening the pressure valve, FWIW.
Thanks.

[majakdragon]

Tarantoga, Welcome to the DIY Forums.
Did you open a hot water faucet while you were draining the tank? If not, you were probably pulling a vacuum on the tank. If you did open a faucet, it could be debis plugging up the drain valve. May have to stick a coathanger into the drain while draining. I am guessing you didn't open a faucet. Good luck and reply back with any other questions.
One last thought. At the age of your heater, the diptube may be damaged or eaten away. This tube is located in the opening for the cold water. It just sits in the opening under the cold water inlet pipe. If you remove the piping, you should be able to stick your finger in it and pull it out for inspection. The diptube takes the cold water to the bottom of the tank and thus pushes the hot water out the piping. If the diptube is damaged, the cold water "short circuits" and goes directly out the hot water pipe and results in less hot water.

[Tarantoga]

Tarantoga, Welcome to the DIY Forums.
Did you open a hot water faucet while you were draining the tank?

Definitely. I opened both of them in the house, but not the one that goes to the washing machine (that valve is bad and I don't want to mess with it currently).

If not, you were probably pulling a vacuum on the tank. If you did open a faucet, it could be debis plugging up the drain valve.

Perhaps I'm confused, but I observe the hot water coming out in limited amounts, and it comes out pretty freely--just not in the amounts that I would expect.

One last thought. At the age of your heater, the diptube may be damaged or eaten away. This tube is located in the opening for the cold water. It just sits in the opening under the cold water inlet pipe. If you remove the piping, you should be able to stick your finger in it and pull it out for inspection. The diptube takes the cold water to the bottom of the tank and thus pushes the hot water out the piping. If the diptube is damaged, the cold water "short circuits" and goes directly out the hot water pipe and results in less hot water.

I had read the accounts of diptube problems prior to posting initially. If the diptube were damaged, then to my mind it would be less likely that I could turn on the cold water during the draining procedure and get that same cold water coming out the drain tube while still being able to run hot water from the tap immediately after completing the draining procedure.
Perhaps I'm wrong about that, but it's just hard for me to picture just how a reservoir of hot water is hiding out in there.

I'm about to disassemble the thing a bit (planning to remove the heating element) to see what's up. I'll check back in later.

[majakdragon]

Even if the diptube was missing you would still get full flow of cold water into the tank. The diptube is exactly that, about an inch in diameter piece of plastic tube that merely takes the water to the bottom of the tank. Thats why they are so cheap to replace, theres really nothing to them. Looks like a tube to separate golf clubs in the bag.

[Tarantoga]

Even if the diptube was missing you would still get full flow of cold water into the tank.

Right, I realize that. My confusion consists of figuring out how the cold water gets from a shortened or missing diptube to the bottom of the tank without cooling down the hot water that I'm able to draw from the heater immediately after draining it. I get more hot water from the drained tank via the hot water tap in the sink than I get from the drain valve during the draining procedure itself, AFAICT.

The diptube is exactly that, about an inch in diameter piece of plastic tube that merely takes the water to the bottom of the tank. Thats why they are so cheap to replace, theres really nothing to them. Looks like a tube to separate golf clubs in the bag.

If the diptube were intact, then I could imagine that sediment would permit the cold water to drain from the tank while sediments collected around the diptube were able to maintain a reservoir of hot water above the bottom of the tank where the drain valve is found.
I'll check in shortly after I pull the thing apart a wee bit.

[Tarantoga]

:lol:
Okay, so I wasn't expecting so much trouble yanking out the element. I removed the bolts but the thing might as well be welded in place for all of my inability to budge it.
What's the recommended tool for this job? I've tried both to tug it and twist it with a vise-grip, but to no avail. I'm a bit concerned that I'm going to break the end off the thing. Is there a risk of that?

BTW, I did achieve more complete drainage than previously by opening the pressure valve, but the water came out clear, MOL, and still at a fairly leisurely pace.

[majakdragon]

Whoever installed it may have put a sealer on it. Try tapping with a hammer and chisel where it meets the tank. Don't get TOO carried away but this may break the sealer or corrosion that is holding it.

[Tarantoga]

Thanks, majakdragon.
I had to reassemble it for now, but I'll take another crack at the thing this weekend.
:coffee:

[Ed Imeduc]

18 years on the tank and run out of hot water. Both elements good??? Tstat good?? Have had where it takes 4 guys to carry or wheel the tank out. Its so full of like rock lime and calcium. Have had to fight hard to get some bottom elements out with all the hard stuff down there . Sometimes the bottom drain will still drain and run clear even with all that in there,cause its hard like.

Id look for a new tank My .02cents

ED :wall:

[Tarantoga]

18 years on the tank and run out of hot water. Both elements good??? Tstat good??

It's a one-element tank, and the water tastes okay (I'm not in the habit of drinking the stuff that comes from the hot water tank, of course).

Have had where it takes 4 guys to carry or wheel the tank out. Its so full of like rock lime and calcium. Have had to fight hard to get some bottom elements out with all the hard stuff down there . Sometimes the bottom drain will still drain and run clear even with all that in there,cause its hard like.

I've got my suspicions along those lines, most definitely. My area does boast some impressively hard water, so it's somewhat against the odds not to run into this problem eventually.

Id look for a new tank My .02cents

ED :wall:

It seems like you should be able to fill it with vinegar and dissolve the lime.
:smile:

I guess the fact that nobody does that (AFAICT) is a good indication that it isn't practical.
Thanks for the two cents, Ed.

[majakdragon]

The reason you don't get a full continious flow of hot water when draining could be,the sediment is "channeling" the water. This happens when the sediment is thick and holes or channels are created to allow the water to flow. Sort of like when you pour water through sand. The water does not funnel through one hole but several channels. As the sediment moves it opens or closes channels. This is why the water flows in odd amounts and ways. If there is enough sediment in the tank to cause this, your only viable choice would be to replace the tank. Yes you probably could disolve the sediment with a vinegar solution,however because of the sediment sitting against the tank wall it has probably rusted somewhat. With the sediment now removed the tank is weaker in these locations. A leak is eminent and a huge mess is to follow.

We can not tell that you must replace the tank as it is your choice. We are here only to explain the potentional dangers of not replacing it as it is so old.We understand the object of saving money, however by the time you replace all the parts you speak of, you could have bought a new heater with a warranty.

[Tarantoga]

The reason you don't get a full continious flow of hot water when draining could be,the sediment is "channeling" the water. This happens when the sediment is thick and holes or channels are created to allow the water to flow. Sort of like when you pour water through sand. The water does not funnel through one hole but several channels. As the sediment moves it opens or closes channels. This is why the water flows in odd amounts and ways. If there is enough sediment in the tank to cause this, your only viable choice would be to replace the tank.

That makes excellent sense, especially now that I've got the element out and can see the big pile of sediment reaching probably 12" up from the bottom of the tank--if not more. It's amazing that the lone element achieved the results it did. I suppose all that warm limestone helps to a degree.

Yes you probably could disolve the sediment with a vinegar solution,however because of the sediment sitting against the tank wall it has probably rusted somewhat. With the sediment now removed the tank is weaker in these locations. A leak is eminent and a huge mess is to follow.

The tank is allegedly glass lined.
Perhaps this is a naive question, but should that make a difference (what with glass being rust-resistant and all)?

We can not tell that you must replace the tank as it is your choice. We are here only to explain the potentional dangers of not replacing it as it is so old.We understand the object of saving money, however by the time you replace all the parts you speak of, you could have bought a new heater with a warranty.

So far I'm only in for a new gasket, AFAICT. :)
If the rust is an unavoidable problem, then I'll probably go with a new water heater. If the glass lining makes more than a neligible difference, I might yet attempt the resurrection.
OTOH, I just did a wee bit of research on the glass linings, finding in effect that they are never perfect, therefore the rust is very probably an insurmountable problem.
Thanks very much for the advice!