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Tanklets > Not Enough Hot Water

Not Hot Enough

Q: Hey guys just recently moved into a new house(well preowned house). But I noticed that the gas water heater is always luke warm. So looked at the water heater and the thermostat is at the very hot setting but still doesn’t get any hotter than usual. I see all the burners are working as it should too. So that’s about where my troubleshooting ends on my part since I don’t know much about gas water heaters. Any ideas or help would be great.

A: There are a lot of possibilities, so let's start by getting some information. When you say it's always lukewarm, where are you testing? At a faucet or at the water heater drain valve. If you've tested at a faucet, try at the drain valve and see if it's the same. Meantime, we'd like a picture of the manufacturer's label on the side showing the serial number. -- Randy

Q1: Tested from every faucet in the house. I haven’t tried the drain valve yet. The thermostat is set to very hot with no change in temperature.

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A1: I'm afraid this isn't what I had in mind. There should be a label glued to the side of the tank that shows make, model, serial, gallonage etc. If it's an old tank, certain things are likely that won't be the case with a new tank. But meanwhile, use the Tanklets link on the left side of the Tank topics index and when you get there, click on Cross Connections and perform the test described. Let us know the result and get us that label.-- Randy

Q2: This must be it.

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Also the copper pipe on the cold side of the heater is a little bit warm about half way up the pipe too. Not sure it that’s normal or not.

A2: Hello, I think I follow what Randy's been thinking. One thing that may be happening is a cross connection in the piping.  The fairly simple test for it is to turn off the cold supply to your water heater, then open a hot tap.  Does the water stop flowing in a few seconds or does it keep running? If it keeps running, there is a cross connection to find and fix. There are other things to look at, but do let us know what the results of the cross connection test are and we can go from there-- Larry

Q3: I did the test and the cold water did shut off. However the valve on the cold side of the heater shut off the hot water. Not sure if these pipes are installed correctly. Also someone mentioned a shower valve cartridge that could cause the problem too.

A3: That's true, but if the cold shutoff stopped flow, it's not that. The heater is old enough that there is a chance that it could be a breaking dip tube. They usually last at least 15 years, but it could be that. The pipes above the heater being warm is normal.

I might as well ask right now if the water is cooler after no use, and gets hotter when someone has been using water.-- Randy

Q4: Yes it is cooler after no use it does get a lil hotter but not much. In my earlier post I mentioned that the thermostat is set to very hot. So I’m theory the water should be scalding.

A4: Hi, Another quick test is to put a hand (or finger tip) on both the hot and cold pipes on top of the heater. Have somebody turn on a hot tap. Feel the temperature changes in both lines. The cold side should cool down while the hot side should heat up. (If they don't do that and the cold line gets hot, the pipes are reversed!)

If the hot side heats up to be hotter that what you're getting from the taps, there must be a problem out in the plumbing. If it heats only up to the delivered temperature, the problem is likely the thermostat. Thermostats are not cheap, your heater looks like it might be supplied with softened water and it is somewhere between ten and thirteen years old. The softened water makes anodes get used up faster, which implies there is a higher likelihood of rust damage inside of the tank.
If the hot side gets hot initially, but then cools some, the dip tube is probably bad. Again, let us know what you discover.-- Larry (9/26/19)

Hot Water Shortage

Q: Not only have I read through your introduction and PM suggestions for water heaters, I've printed out everything and will try to attempt service. Before I get started, I would like your opinion on a newly developed problem. There are three (3) of us in a household who all take showers in the morning. It begins with our niece who takes long showers, but in my opinion, not 40 gallons worth (the size of our tank). By the time I get in and then my husband, the water is warm. I can't get it hot, no matter how much I turn the faucet.

This is not everyday, but has started a couple of weeks ago and is happening more often. I sincerely do not feel it is a 15 minute shower that has given us this new problem, but rather something that is happening with the tank. The tank is 5 years or less. The size is 40 gallon. It is in the garage up off the floor. Strapped to the walls and wrapped in a blanket. We do have a water softener. The tank was changed out when we had a plumbing redone to copper. Do you have any suggestions where I should start looking for the problem? Thank you very much.

A: We have several thoughts. First, did the routine of all three of you showering at about the same time start recently, or were you able to share the water successfully until a couple of weeks ago? If this is a new routine, you may indeed be running out the hot water supply, especially if you don't have low-flow showerheads. It really doesn't take too long.

I'd check the showerheads. Hold a 1- or 2-gallon bucket under them and see how many seconds it takes to fill. But think about it: 3-gallon-a-minute showerheads would only give you 13 minutes with a 40-gallon tank. So a 15-minute shower? If that's the case, maybe your niece should consider everybody else.

However, if the three of you successfully took showers up until a couple of weeks ago, then there is a possibility that the dip tube is split or broken. It's a plastic tube that sits on a ring in the cold-water port and takes the incoming cold water to the bottom of the tank to be heated. Hot water rises. So if the tube breaks or splits or falls into the tank for some reason, you get a little hot water, then lukewarm or cold water because the cold is entering and mixing with the hot right at the top of the tank.

You'd check by disconnecting the plumbing on the cold side, taking out the nipple, and then taking out the dip tube, which can sometimes be done with your little finger, other times with a dowel inserted and worked out with a mixing motion. Let us know what you learn. We're always interested. -- Larry (1995-2000)

40 Gallons = Five Minutes

Q: I have been going back and forth with my landlord about my hot water heater for one year now! Although we have a 40 gallon hot water tank (that my landlord promises is working fine), we can only take a 5-7 minute shower before we are completely out of hot water.

Also, in order to keep the shower a comfortable temperature, during that short time we have to continually adjust the water, turning the cold water down until, by the end of the 5-7 minutes, the cold water is completely off. I say that a 40 gallon tank should provide more than one 5-7 minute shower. As it is, only one person can take a shower, and they have to do it fast.

He sends maintenance men out here who insist that the hot water heater is working fine and who act like I am crazy. Today maintenance men came out, measured the temperature at 118 degrees from the hot water, and got the shower to run at 100 degrees for (supposedly) ten minutes. I have timed my showers on multiple occassions, and by the 5-7 minute mark I am completely out of hot water (with the cold water turned off). Help!

If the heater is working, there must be a plumbing or electrical problem. Am I really crazy? I have never had this problem before, and I actually have to go to friends' and relatives' houses to take a reasonable length shower -which I do with no problem (and they all have 40 gallon tanks!). The hot water heater is a 38-gallon electric hot water heater by GE with "first hour capacity" of 45 gallons. The temperature is set at 120 degrees. Our shower has two handles, one that controls the hot water and one that controls the cold.

A: How long have you lived there? Has it always been like this? If not, when did this start? And another thing: If you lived in an apartment served by a commercial water heater that can provide almost endless hot water and moved to one with a 40-gallon tank, you might well think there was a problem when, in fact, you are just overreaching the limits of the latter.

Beyond that, here are three possibilities. The first, remote, but not impossible: the tank was installed backwards, with the cold water coming in the hot side where there is no dip tube and the hot coming out the cold side, where there IS one. That would make the tank draw hot water down to the bottom, where it's colder before going out to the faucets.

Second possibility: you have high-flow showerheads and unrealistic expectations. You don't really have 40 gallons of hot water. You have about 30. Even with 3-gallon-per-minute low-flow heads you can run that out pretty fast.

Third possibility: The dip tube (cold-water inlet tube) is damaged or missing. That would allow incoming cold water to mix with outgoing hot and seriously compromise the function of the heater. This is more likely if the tank was made between August 1993 and March 1996, since there was an industry-wide problem with dip tubes then. -- Randy (12/10/04)

Thermostat set too low

Q: I just installed a new (Reliance, 50-gal. duel element) electric water heater. I saw the section within the website describing the (troubleshooting) reasons regarding my subject, i.e, distance and dip tube. Therefore, I do not understand why either of these would apply; the past w/heater didn't have distance problems and a new w/heater (I hope) would not have damaged dip-tube...??? Shower (water) temp diminish before the end of my shower more than the previous W/heater. I live alone and nothing has changed other than the new water heater. Did I miss something within the 'install' or something else? Thank you for responding!

A: Sounds like your lower thermostat is set too low. The top thermostat only controls the temperature above the top element. And hot water floats on top of water less hot. 130 F is good to kill any dangerous bacteria. Too hot risks scalds for the very young and elderly. If you top thermostat is set at 120 and the lower thermostat is set at 100 you have about 15 gallons (in a 50 gallon WH) of hot water. At 120 you will use mostly hot for a shower. So at 3 gpm you will have a 6 minute shower and then the 120 F water is gone. -- EnergyExpert

Q1: That sounds like the problem I am having. I did re-set the Thermostats a day or so after install (it was set about 118 F.), I set both to about 135F and maybe I didn't set the Lower Element to the same setting, but I know it was close, but maybe not close enough. OR could it be that the reset button didn't reset the lower element, I know the top element did reset(?); I will repeat the process and check back to the Forum. Many Thanks!

A1: Most lower thermostats do not have a reset button. The red button is called the emergency cutout (ECO). Thermostats only cut one leg of power to the elements. A stuck thermostat or a broken element leaking to ground results in a run away WH. The ECO trips on high temperature and opens both legs of power. Placing the ECO on the top thermostat protects the whole WH; regardless of what fails electrically the ECO kills the power. -- EnergyExpert