Lukewarm initially, hot later


  #1  
Old 09-26-04, 02:46 PM
waller04
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Lukewarm initially, hot later

When I get up in the morning the water is not very hot. The first one in the shower is always disappointed. After the first shower, wait 10 minutes and then the second shower is plenty hot. Its a 75 gallon gas hot water tank.

I replaced the thermostat four months ago. It appeared to solve the problem at that time, but the problem has gradually returned to the point where it is now no longer accpetable once again. As an interim solution we run the dishwasher on a timer such that it runs 1/2 before anyone gets up. Any thoughts on how to fix the problem correctly?

Thanks greatly for your assistance.
 
  #2  
Old 09-26-04, 04:07 PM
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Sorry about that.......I need to slow down on reading these postings.



Might be a dip tube issue or the thermostat is malfunctioning.


How old is this water heater?
 

Last edited by DUNBAR PLUMBER; 09-26-04 at 06:07 PM.
  #3  
Old 09-26-04, 05:33 PM
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Steve,

It is a gas heater not electric.
 
  #4  
Old 10-06-04, 08:05 PM
waller04
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Tried to pull out the dip tube to no avail. Couldn't get it out of the tank. It says "hydra-jet" on the side, so perhaps its something fancy. I was hoping it would just lift out of the inlet, but appeared to be sealed in rather well. In any case the replacement I had picked up at a big box store was returned.

First couple of days now, it appears to be warmer on initial water flow in the mornings. I'm certain I did nothing to improve the performance. Would the simple fact of draining the tank make a difference? The water runs clean at all times - as if there is no sediment in the tank. The tank is 5 years old.

Thank you greatly for your advice earlier.
 
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Old 10-06-04, 08:25 PM
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Sometimes it is hard to see the dirt/sediment remove from the tank, but draining the tank periodically greatly improves the life of the water heater.



Follow the instance of leaves accumulating in a garbage can over years slowly deteriorating the bottom.



Any chance you have a washing machine connected to a laundry tub with both hot and cold mixing?
 
  #6  
Old 01-30-05, 02:06 PM
waller04
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I never really figured this one out. I don't think I have appliances mixing anywhere, but I could be wrong...

I turned up the temperature on the tank to the hottest setting just below scalding (it was on the 'energy saver' setting), and that seems to be acceptable. The first shower in the morning is sufficiently hot, and all subsequent showers as well. I suspect its just masking the problem, instead of an appropriate solution but it currently meets our needs without further time invested. (I know - my gas bills are going to be higher...)
 
  #7  
Old 02-05-05, 04:26 PM
mikedudl
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Do you have an anti-scald valve on your shower faucet? Some ( Delta is one ) use a cartridge that can be installed 180 degrees off, if not careful. I know, I did it years ago. Also, if it is really old and worn, or the retaining ring is loose, maybe the mixer valve bypasses cold to the hot side until, after a 10 minute shower, it heats up and expands enough to seal and direct the cold and hot through their proper passages.
 
  #8  
Old 02-20-05, 12:59 PM
Frank42
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hysteresis could be the problem

I have a similar problem with a new WH. Bradford-White told me that there is up to a 24 degree hysteresis in their WH. That means that overnight, the water could be 24 degrees lower than I set the WH to be. That is really cold! If you can draw enough water from the WH to cause it to come on, the water temp will now heat up to the original setting. All WH have some hysteresis, but this is too much. They do this so we save energy, but the result is cool morning showers. Sounds like you found a way to get the WH to come on before your morning shower.
 
  #9  
Old 03-13-05, 08:26 AM
nelsoncomputer
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Thumbs up Lukewarm mornings - I think Frank is correct

We have had the same problem in the mornings with the lukewarm not hot water. I have always thought the water just sits and cools off. No circulation at all through the heater during the night.

If the 'hot' water is run for 5 minutes or so, and then you wait 15-20 minutes, the hot water heater has sensed the temperature drop from the cold water, and heats the tank back up.

I am going to look at a installing a circulator pump on the hot water line at the water heater and a "crossover valve" under the sink in the bathroom.

I have heard that Home Depot has carries the retrofit style water circulator. $199.95. Has the valve that goes under the sink, and the pump.

I usually don't take the first shower in the morning, but a happy wife is a happy home.


Hope this helps,

Dave N.
 
  #10  
Old 03-13-05, 11:44 AM
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wow, this is interesting. I've been having the exact same problem with hot water as well with my gas WH. The first morning shower is always lukewarm at best, and then after 20 minutes or so the water is plenty hot.
 
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Old 04-01-09, 01:43 PM
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Can hysteresis be adjusted?

I have the same problem with a brand new gas water heater. If you set it down to about the 125 degree mark (for the safety of little kids), it apparently has about a 15 degree (maybe more) hysteresis curve built in. Is there anyway to adjust this? (If I had wanted only 110 degrees, I would have set it that way!) Or has someone thought of a work-around? (Besides setting the alarm for 5:30 am and getting up and running the water for 10 minutes for the 6:30 showers. :-) )

Thanks.
 
  #12  
Old 04-01-09, 09:07 PM
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a recirculation line with a temp sensor is about the only fix i can think of
 
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Old 04-08-09, 01:22 PM
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Done by design

Thanks plumbermandan.

I found out on the AO Smith website that basically, water heaters are designed to run this way. They call it "standby heat loss" and it's not adjustable and they have their reasons for doing it. (See their website for details.)

So apparently any fix to the problem does have to come from outside the water heater.
 
 

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