Any water heater experts out there?

[OUWxGuesser]

Here's the scenario:

Wife and I live alone in a home that has a 60g gas water heater (overkill for 2 of us, but it's what the house has). While the water is plenty hot, if the water goes unused for a period of time, typically a half-day or so, it comes out lukewarm (even if you wait a minute or so for it to cycle through the water in the pipes).

Example: Little water usage tonight. Tomorrow morning, wife gets in shower and is treated to a luke-warm shower. An hour later, I get up and take a shower. Water is plenty hot.

How does the thermostat on a water heater work? Is it simply heating the water up for a period of time as it enters the tank... and thus cools with time? Or does it actively warm the water 24/7 keeping a steady temperature? I'm wondering if its just that we don't go through that much water on a 60g tank.

The ultimate question is whether to call the repairman. I already drained the tank and rid it of sediment. I also installed foam insulation around the warm water piper where I had access above the water heater. Next step (assuming the thermostat is ok) is to add that wrap insulation around the main body of the heater. Probably a good idea considering the energy rating on it is 1 point below the least efficient in this size :mad:.

[Sooner_Havok]

My guess, heat rises. In a tank that big that hot water will go to the top of the tank, while the cooler water stays towards the bottom where the water leaves the tank. The hot water at the top "fools" the thermostat into thinking the water temp is ok, but when the water starts to be taken out at the bottom, the new water coming into the system drops the actual and measured temperature of the tank, causing the heater to kick on.

Edit: That would explain why no matter how long you run the water, it doesn't get hot at first, since you are just diluting the real hot water with cold water, but after a while has pasted after the initial usage, the temperature kicks up because the whole tank has been heated.

I am talking out of my ***, but you have to admit it does sound good ;)

[Turd_Ferguson]

The dip tube on the cold side sometimes breaks. This allows the incoming cold water to contaminate the outgoing hot water. Hope this helps.

Edit to add: My tank has cold water coming in at the top, and hot water going out at the top. The cold side has a dip tube on the inside the directs the cold water to the bottom of the tank. The hot water should be at the top.

[OUWxGuesser]

Thanks for the responses.. I did some more ninja searching on google and found this morsel:


Residential Gas Water Heaters

Most likely you are seeing what is called standby heat loss. Stand by heat loss is basically the reduction in water temperature while the water heater is not in use. Take a look at the information below to explain this more.

* All modern water heaters experience standby heat loss. The modern water heater is so well insulated that the standby heat loss is very slow and is not usually noticed until hot water usage stops for a length of time (like over night).
* The thermostat on all residential gas water heaters has a plus or minus factor of 10°F when shutting off.
* The thermostat has a differential of 15 to 25°F when turning back on. This means the heater could drop to as low as 95°F before the thermostat would initiate firing of the burner. If the differential were closer, then the gas-fired unit would "stack" creating the potential of activation the built in ECO (energy cut off) which would require replacement of the thermostat.
* Older heaters were set at the factory from 140 to 150°F.
* The standby heat loss is non-adjustable and has everything to do with inactivity.

Considering the water heater is in the basement... I'm guessing this may be the culprit.

[stoops the eternal pimp]

you need a 40 gallon friend

[phead903]

http://images-partners-tbn.google.com/images?q=tbn:oopnIEBm2NReGM:waterheating.rheem.com/content/resources/images/attachments/WaterHeater.jpg

Go tankless!