Hot water barely lasts 10 minutes in the shower... a few questions.


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Old 03-16-08, 11:38 AM
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Hot water barely lasts 10 minutes in the shower... a few questions.

So I think I have a 30 gallon hot water tank, even though it looks the same size as my upstairs neighbors' tank which is 40 gal. The hot water doesn't even last long enough to finish a shower. I asked my landlord about it and told him I'm try turning up the thermostat which didn't do a thing. It really seems like something is wrong.

I am going to call him, but I tried something, I have been gone for about 24 hrs. and I went downstairs and felt the hot water pipe. It was pretty warm, warmer even than my neighbors. Seems wrong to me. I do know for absolute sure this is my tank and it's the pipe that I assumes feeds hot water TO my apartment. I felt the water going through the pipe when I left my hot water in my sink on.

Anyway: is this wrong? I would think it should be cold. Why would the pipe be hot? Warmer than my neighbors who have been home all night and day? Just wanted something to suggest to my landlord when I call.

Thanks!!!
 
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Old 03-16-08, 02:21 PM
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Actually i just felt both pipes coming out of the top. One is marked cold, one hot. They're both hot. And on my neighbor's tank they're both warm. i'm confused!
 
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Old 03-16-08, 02:57 PM
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Water heaters 101.

I am assuming that you are in the US and not the United Kingdom as their water heaters are quite a bit different.

Water heaters can be divided into two main types, storage tank and instantaneous. Instantaneous heaters heat the water only when hot water is being used and storage tank heaters store a quantity of water at the desired temperature. Instantaneous heaters use a large energy input but only when actually heating the water. Storage tank heaters use a much smaller rate of energy input but for a long time period, slowly heating the water within the tank.

Energy input can be from any one of several sources such as burning gas, boiler water or electricity. All three of these energy sources may be used in either instantaneous or storage tank water heaters.

Storage tank heaters can usually deliver about 70% of their nominal gallons capacity before the water starts to turn noticeably cooler.

After an extended period of not using any hot water a storage tank heater will contain its full capacity of water at a given temperature. Both the cold water inlet pipe and the hot water outlet pipe will feel warm-to-hot to the touch.


Most residential shower heads are rated for a 2-1/2 gallon-per-minute (GPM) flow rate. If the temperature of the hot water is set at or below 120 degrees most people will use only hot water in their shower. Raising the temperature setting of the water heater will require that a certain percentage of cold water will need to be mixed with the hot at the point of use to prevent scalding.

If you have a 30 gallon storage tank water heater then you will only be able to "draw" about 21 gallons of hot water before the water turns noticeably cooler. At a flow rate of 2-1/2 GPM that calculates to about 8-1/2 minutes of shower time IF you have the water heater set at anything lower than about 120 degrees F.


Is your water heated by burning gas or by electricity?
 
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Old 03-16-08, 03:08 PM
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When water has not been drawn from your tank for some time and yours is the type that has the cold water entering from the top it is normal for the cold line to feel warm or even hot.
Convection from the tank will make it so.
However when water flows the cold water line should turn cold.

As far as offering suggestions to your landlord you really have no need to.
He is obligated to fix it for you and his electrician would be the one to worry about it.
 
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Old 03-16-08, 04:02 PM
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Originally Posted by furd
Water heaters 101.

I am assuming that you are in the US and not the United Kingdom as their water heaters are quite a bit different.

Water heaters can be divided into two main types, storage tank and instantaneous. Instantaneous heaters heat the water only when hot water is being used and storage tank heaters store a quantity of water at the desired temperature. Instantaneous heaters use a large energy input but only when actually heating the water. Storage tank heaters use a much smaller rate of energy input but for a long time period, slowly heating the water within the tank.

Energy input can be from any one of several sources such as burning gas, boiler water or electricity. All three of these energy sources may be used in either instantaneous or storage tank water heaters.

Storage tank heaters can usually deliver about 70% of their nominal gallons capacity before the water starts to turn noticeably cooler.

After an extended period of not using any hot water a storage tank heater will contain its full capacity of water at a given temperature. Both the cold water inlet pipe and the hot water outlet pipe will feel warm-to-hot to the touch.


Most residential shower heads are rated for a 2-1/2 gallon-per-minute (GPM) flow rate. If the temperature of the hot water is set at or below 120 degrees most people will use only hot water in their shower. Raising the temperature setting of the water heater will require that a certain percentage of cold water will need to be mixed with the hot at the point of use to prevent scalding.

If you have a 30 gallon storage tank water heater then you will only be able to "draw" about 21 gallons of hot water before the water turns noticeably cooler. At a flow rate of 2-1/2 GPM that calculates to about 8-1/2 minutes of shower time IF you have the water heater set at anything lower than about 120 degrees F.


Is your water heated by burning gas or by electricity?
Thanks for all that info. As far as what energy source I have no clue but I would tend to think gas, because I have gas heat.

I put the setting up to the highest temp, I don't know how hot that would be but i would assume hotter than 120. Like I said, turning the temp up did absolutely nothing which I thought was a bit odd.

Originally Posted by GregH
When water has not been drawn from your tank for some time and yours is the type that has the cold water entering from the top it is normal for the cold line to feel warm or even hot.
Convection from the tank will make it so.
However when water flows the cold water line should turn cold.

As far as offering suggestions to your landlord you really have no need to.
He is obligated to fix it for you and his electrician would be the one to worry about it.
If it's just cause it's a 30 gal tank then I might be SOL. Which really sucks, because this is really bad.
 
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Old 03-16-08, 04:10 PM
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It would be a good idea if you would turn back the setting on the tank to where it was.
If set too high you could scald yourself and possibly cause the pressure relief to vent.
 
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Old 03-17-08, 01:30 PM
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Yes, I'd say get the landlord to fix it. It's probably fastest and easiest to just replace. If it's electric, it could be one of the elements gone bad. Or, if it's old, it could be sediment build up and you may THINK you have 30 gallons but you really only have 10. I'm guessing that because it is a rental, the tank has probably NEVER been flushed out. And if it's old, the bottom is proably rusted and just waitng to drop out, most likely at a time when no one is aound to notice the flood for two or three days. THEN the landlord has a HUGE problem on his hands. Cheaper to just replace now.

Whatever the problem, the landlord should get someone in there to fix it.

Good luck,
Tom
 
 

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