People in my house can take multiple long showers with no problem and plenty of hot water (I do have flow-restricted shower heads). However, when I try to fill my fairly large bathtub, I get literally 3" of water before the hot water is gone. I have a 55 gallon electric hot water heater & can't imagine not being able to fill the tub at least half way, especially since I'd mix cold water in with it. It has been this way for several years and I have no clue why. I have recently replaced both thermostats on the heater with no change in the amount of hot water available for my tub. Any ideas?

Part of the issue is definitely going to be the fact that the tub spout delivers much more water than the shower heads, but you already knew that!

However, you should be able to fill a regular size bathtub with warm/hot water without too much difficulty having a 55 gallon water heater.

Have you tested the hot water heater ELEMENTS? It seems reasonable to test these next! Here, an easy test is to shut off the power (confirm via tester), remove the wires from BOTH elements and take continuity tests across the screws on each element. If you don't have continuity when testing across the screws of an element than that element needs to be replaced... ;)

Back to you...

Mark

A deteriorated dip tub might, emphasis on might, have an effect here. Due to the differences in flow it might not be as noticeable from shower head.

Are you trying to take a bath after all of the others have showered... I mean within a short period? That could be a problem because the water heater cannot recover very quickly.(I am presuming it is electric which have the slowest recovery rate). A 55 gallon water heater should easily fill a tub. Easily. Have the water heater check or wait at a least an hour after everyone else has showered.

I appreciate all the quick responses!

Mark, I'm afraid I don't have the skills or tools to test the elements. I have no idea what a continuity test is :(

HK, I'm not sure what a deteriorated dip tub is either!

Handyman, I tried filling the bathtub tonight & no one has showered or done laundry since early morning so I should have tons of hot water. & I agree, it should be able to fill the tub with no problem.

I had a similar sized tub & hot water heater in my last house & never had a problem. So I believe it's something specific to this house. And the tub in question is inside the master bathroom so distance from the hot water heater shouldn't be an issue & it's 55 degrees out so cold pipes, etc aren't the problem either.

Is there any chance there could be a different pipe running just to the tub or could it get hot water from a different part of the tank or something along those lines & how would I know? I say that because there is also rust colored sediment in the water. I have never noticed this in any sink or shower in the house & haven't had any noticeable discoloration in them either & have lived here for 3 years. Though maybe it's not actually rust/hard water but from something else & is why it's not noticeable in other places...

Any other ideas?

Continuity test uses an electrical tester to check for continual connection through a circuit. Testers can be bought at a hardware store or super center, and are inexpensive and handy for troubleshooting. As an example, you can test a wire by placing one test lead on one end of the wire and the other test lead (electrical tester has two test leads) on the other end of the wire. The tester will either beep or light-up if the wire is good. If a heating element is broken, it will not have continuity. The dip tube, inside your water heater, brings the cold water to the bottom of the water heater. If the tube is damaged cold water could flow out the hot outlet before getting heated. Hope this helps. Noticing sediment and staining from the spout makes sense because it has greater flow. Has your tub filled up with hot water before? How old is you water heater?

Water for the tub would not come from any special piping or special part of the water heater. You have a 50 gal electric water heater. You said that the thermostats have been replaced.

You have two heating elements, each controlled by a thermostat. Thermostats may be working but if a heating element is burned out, you are still not heating water.

Doing a continuity test is a way of telling if the heating element is or is not good without removing it. It's a simple check, if you can't do it find a friend or handyman that can. Unfortunately, if you have a bad element, it will be the lower one. If it were the upper one, the upper thermostat would never be satisfied and the lower one would never come on. Only means that you have to drain the tank completely to replace.

If you see discoloration in the bath water it probably means you have sediment in the bottom of your water heater. How long has it been since you flushed the water heater. An excessive build up of sediment means the water heater is not going to drain or is going to drain very slowly.

As MStephens stated a dip tube is a plastic tube on the cold water input pipe that makes the incoming cold water go to the bottom of the tank. If that tube disintegrates, and they occasional do, the incoming cold water just travels across the top, over to the hot water output side. Hot water in the tank stays there.

Ir you wish to do a continuity check, pick up a multimeter at any Home Depot, Lowe's, Sears or even Kmart, and someone can step you through it.

The hot water heater is about 7 years old. I've lived here for 3 years & have never been able to take a hot bath :( Every so often I try again, thinking maybe something magically changed, perhaps the little bathtub fairy came and fixed the problem, but alas, I've not been so lucky. Some months back, the sediment was much worse than it was last night, where it was barely noticeable in comparison. I've never flushed the tank. Is this something I should do?

I've never had an issue with taking showers and running out of hot water - except on days when my electric company 'takes over' my hot water heater & turns it off temporarily. I'm on a program where they can do that & in return they make repairs on the tank. Initially I thought that's why I can't fill my tub - that they had turned the heater off for a few hours & I had run out of water - but now I've tried taking a bath so many different times I'm pretty sure that isn't the case.

Hi again, MStephens

You said, "I'm on a program where they can do that & in return they make repairs on the tank"

If this is the case, then stop guessing here and call them out to test the ELEMENTS as suggested. If they test the elements and they test OK then ask them to check the dip tube as Harold suggested. If they balk in any way, show them how quickly you run out of hot water by filling the tub.

My bet is on the lower element... ;)

Finally, while the technician is out there ask him/her to flush the tank out for you... should only take a couple minutes or so!

Mark

Mark, Thank you - why didn't I think of that? I just called & they are coming in a couple of days. They can test the elements at least, according to the rep I talked to.

Glad they will back up what they promised! Please let us know what they find, OK?

Good day!

Well, not much to report, I'm afraid. The electric company checked the elements, said they are fine & replaced the thermostats & set the temperature to 125. They don't have the ability to check the dip tubes or drain the tank (or it's not within their job description). Long story short - still not enough hot water to put more than about 3" of water in my garden tub.

I'm on a program where they can do that & in return they make repairs on the tank.


They don't have the ability to check the dip tubes or drain the tank (or it's not within their job description)

I would cancel their program. They said they would fix your water heater and they are not doing it. Anybody can drain and flush a water heater. Any body that claims to do repairs to a water heater can replace a dip tube.
They just didn't want to do it. At this point I don't know if I would trust what they are saying about the thermostats and heating elements. You said that they checked the thermostats, did they even check the elements.

MSstephens, I can replace a dip tube, and I'm by no means a plumber. It's very easy. I've had this issue before, and again, I'm not a plumber, but I'd change out the dip tube next. It's not expensive. Get a new dip tube at your local hardware store. I'm sure the pros on this site would talk you through doing it. It's really not at all hard.

That would be the next step if I were you.

I'd also cancel the company that said they couldn't do it for you. Seriously, if they claim to be pros but can't or won't replace the dip tube, they're not worth the money you're paying them.

You don't spit into the wind, you don't step on Superman's cape and you don't mess with Alty.

You don't spit into the wind, you don't step on Superman's cape and you don't mess with Alty.

LOL! If only more people realized this. ;)

MS. Please try this just to eliminate any weird things that may be taking place with a possible tempering/mixing valve that may be install only on the garden tub, okay? Run the tub until you run out of hot water, then run the shower and see if you have hot water there, or if its cold too. Lots of option here, and most have already been mentioned. Bad lower element, stats (already replaced a couple time as it sounds), bad dip tube, or even possibly the hot and cold to the water heater are reversed ( not likely, but I just had a similar call about good showers, but not enough hot for a bath, and it turned out the hot and cold were piped backwards to the water heater, this will do the same thing as a bad dip tube). Now, all that being said, and if all this checks out OK, it may come down to the size of your tub. Here is another good quick test, okay? Take a five gallon bucket and start filling it with hot water only from the tub, quickly dump when full and start filling again. In this way you can feel the temp of the water and measure the gallons of hot hot water you are getting. Note when it starts to go from hot to warm, to cool, to cold. If you get a true 30-35 gal of hot water, then about five gallons of warm, then it turns cool and cold, then your water heater is doing its job. Please let us know what you find with these simple test's and we will see what we can come up with. We won't install anything less than a 75 gallon gas water heater, or 80 gal electric in new homes with oversized tubs because a standard fifty gas or electric just won't get the job done. Please keep us posted, and good luck.

Thank you all again for your helpful suggestions. I haven't tried checking to see if there is still hot water to the shower after the tub runs out, nor have I determined how much actual hot water is going into the tub, so I'll do those next. Thanks - you guys rock :)

Do any of you have experience with a tankless hot water heater? In the event I need to replace this one at some point - or perhaps for my next house - that's what I'm considering & would appreciate input if anyone has experience with those & knows where to find them for a reasonable price.

Now you may have hit on something. How about installing a whole house tankless water heater. It would probably cost no more than installing a faster recover gas or oil fired water heater. It's my opinion that you are simply using all of the available hot water when filling the tub. What if you try filling first thing of the day before anyone else uses hot water. That will give you a true amount of available hot water.
You must remember that electricity has the slowest hot water recovery time and 55 gallons would take hours not minutes to go from ground temperature(~42 degrees) to 125 or 130 degrees.

I would cancel their program. They said they would fix your water heater and they are not doing it. Anybody can drain and flush a water heater. Any body that claims to do repairs to a water heater can replace a dip tube.
They just didn't want to do it. At this point I don't know if I would trust what they are saying about the thermostats and heating elements. You said that they checked the thermostats, did they even check the elements.

Harold - to be honest, I don't know. I'm on a "load program" through my electric co-op and in return for them being able to turn off my hot water heater at peak times a few times each month, they are responsible for repair/replacement of electrical components, which include elements & thermostat but apparently not much else. The rep who came out said the elements are fine, but there's no way for me to tell if he checked them or not. He didn't offer much in the way of helpful suggestions (like all of you have) & said I'd need to hire a plumber to check the dip tube or drain the tank (even though it sounds like neither of these really require a "professional", just some knowledge).

I'd cancel. You are getting nothing in return for the inconvenience. If they don't come remove their equipment, find a handy man to disconnect their equipment and check your elements . To flush your water heater all you have to do is connect a hose to the drain valve and open the drain valve until the water runs clear.

In addition to all the above responses...

It is easy math: Shower head dispenses water at the rate of about 2.5 gal a minute - and less. Average shower lasts about 3 minutes. Therefore you use 7.5 gal of hot water per shower allowing 4 other people to take showers not running out of hot water.

Tub is a different story. Tub faucet in not flow restricted and dispenses water at high rate of volume. I don't know what kind/type of faucet you have and what's your water pressure inside the house - but generally speaking it can be easily 10 gal per minute. Therefore, you run out of hot water in about 4 minutes. If you tub has 80 gal capacity then it doesn't fill up to the rim before you run out of hot water.

Also, in colder climates and long distance between hot water heater and tub, hot water looses heat very rapidly. In addition, hot water heater is supplied with super cold water from the source taking longer to heat it up.

Combination of all of the above is a shortage of hot water at the spout.

Hope that helps / Milo

An average bath requires 30-50 gallons of water. The average shower of four minutes with an old shower head uses 20 gallons of water. With a low-flow shower head, only 10 gallons of water is used. Does this answer your question? Regards, Tom

I've never taken a 4-minute shower! 10-15 minutes (or more) is pretty common. And I do have a low-flow shower head & don't normally run out of water even if someone else is showering in the other bathroom at the same time. I'll be testing things later tonight to see how much actual hot water I get in the bath before running out & then see if the shower is also out of hot water & will post back. Thanks!

If the hot water comes from the same source for both the bath and shower, when you deplete the hot water with the bath, there will be NO hot water for the shower either.

MS. You said this was a GARDEN tub, yes? Would you say it was quite a bit bigger than a standard tub? If so, volume is your problem. Just not a big enough heater to fill that thing properly. However, many codes mandate a mixing/tempering valve to be installed on jacuzzi style tubs. These valves can fail and cause strange issues at the tub faucet only, like lack of hot water. Do the tests for hot water at shower when tub is running cold. Let us know. Oh, and if you could post a pic of the tub and the tub faucet (should be able to tell if it is a high volume faucet from pics) it may help us determine if the water heater is simply to small.

Also, I have had good experience with gas tankless water heaters as long as the water quality in your area is good. I would steer clear if you are on a well, or any water source that is less than stellar (unless you have a great filtration system and keep it up). I would not suggest an electric tankless, as they many times require electrical service upgrades and they suck the power like nothing else in the home. I have had great luck with NAVIEN tankless. The key with these for whole hole house domestic hot water is to get the largest model (240A I believe) with the internal recirculation pump and run a recirc line to the furthest fixture possible.

I've never taken a 4-minute shower! 10-15 minutes (or more)
Then a 10 minute shower would take only 25 gallons. Still much less then the 30/50 gallons
A tub takes. With a55 gallon heater I figure you have about one bath plus a shower before you start to run out of hot water, Regards, Tom

OK so here's my update. I ran the tub & measured how much hot water I actually get using a 5-gallon bucket & have pretty sad results, I think. I got 20 gallons of hot water followed by 3-4 gallons of warm & perhaps 2 gallons of lukewarm water before running out. So roughly 20-25 gallons of hot water in total. And the shower & sinks gave me just cold water after that so I knew I was completely out of hot water.

I'm not certain of the size of my hot water heater and it's not easily accessible to be able to get to (crawl space through small hole that is wedged shut w/ wood), but was told it was 55 gallon. Now I'm thinking it must be smaller and my problem is simply that the hot water heater is just too small :(

Thank you all for the advice, encouragement & words of wisdom. This site is awesome!

but was told it was 55 gallon. Now I'm thinking it must be smaller and my problem is simply that the hot water heater is just too small.

I would still cancel. If power company reps went in and looked, it seems like they would have told you that. Seems like that would have been the first thing they would have said.

Regardless of why you don't have enough hot water, you are getting nothing in the exchange with the power company. It's a one sided deal.

Well we are back to square one. Either a lower element issue or a dip tube issue, or now it could be a smaller water heater than we first thought? Sorry, but it really is time to bite the bullet, cancel the contract with the power company and hire in a licensed plumber to diagnose the system thoroughly. Now, before I called the plumber, I would at the very least find out the age and actual size of the water heater. If its older and under fifty gallons, I would suggest letting the plumber know on the phone that you may be interested in a new water heater sized correctly for your complete home with garden tub. They should be able to give you all the options that will work for you. Heck, it wouldn't hurt to get quotes and suggestions from a few different plumbing companies. Good luck and please let us know the final tally.

I agree with Lee.
A 55 gallon heater should produce more then 20 gallons of hot water. Check the lower element and if that checks out you may have a dip tube that's broken, Good luck, Tom