I went to take a shower this morning and the water was ice cold. For more than twenty minutes the water ran and never warmed up. Are there common things to check my hot water heater for in this situ

Reasons for this: ???

• bad elements,
  • if one is bad, just replace both
• bad thermostat or both of them?
• broken dip tube / cold water mix tube
  • Notice the "RED" in the 1st pic on the left. 90% + of the tank is hot, with a broken tube, 75% of the tank is luke warm to cold.

Check for them. not that difficult of a fix

You could start by seeing if the thermostat is wide open. Sounds like it is on low or vacay mode. How far is the run between your heater and the bathing area. Might need to insualet some piping.

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I had the EXACT same problem (installed my tankless last winter and worked fine, now this summer it fluctuates, have to turn the shower completely off and then on again to get any hot water and then it only lasts for a couple of minutes!) Argh - it is frustrating!

Here's what I found: the demand for hot water is lower during the summer (hot) months because the "cold" water coming in is already quite warm. You don't need as much hot water to make the shower temp comfortable. SO, my tankless was shutting off due to low flow demand. I've removed the flow restrictor from my shower head and it helped alot but didn't completely solve the prob. Next step is what has been recommended to me by several people but is much more expensive - change the pressure valve on your shower to a temperature valve. Or just wait til winter and it should work ok again :)

Some elements will read with a meter good until they heat up.

Hot water then going to ice cold top element is working and bottom bad. Luke warm water and then goes cold bottom element good and top element bad.

Elements and thermostats are not to exspensive to replace.

If you have power only two thing's left are the thermostat's and the elements.

Sounds like you have a problem with water flow. Since your ground water is warmer in the summer, you mix less hot and more cold in order to get the same warm temperature. If your hot water flow gets low enough, your tankless will start to "short cycle" in order to prevent scalding. Use one of these three methods to increase your water flow at the shower:

1) Clean your shower head and descale
2) Widen the hole in the showerhead's flow restrictor
3) Remove your flow restrictor entirely

Good luck!

You can eliminate the shower control knob possibility by turning on your hot water anywhere else in the house. If you get hot water in other places, then it could be the knob causing it. A substantial lime buildup in the tank can also cause poor heat transfer from the elements to the water.

check diaphrapm valve or micro/switch best of luck

you need to change the cartridge, it is a temp control and is going bad so it keeps you from burning yourself it is like a mixing valve and is givng more cold water, that way you don;t get burned,,

I think the dip tube in your water heater has failed, this is a plastic tube that goes in the cold side of your tank and forces incoming cold water to the bottom of the tank allowing hot water out at the top. When this tube deteiorates the incoming cold water mixes at the top of the tank causing the problem you have. the dip tube runs about 5 bucks but takes someone with pluming skills to install.

I found a way to get warm water in the shower, but I'm not sure it qualifies as a solution. After trying everything else I thought that maybe when I was feathering the faucet in the shower toward the cold side so I would get warm water that at a certain point it blocked the flow on the hot water side enough so that the sensor in the hot water heater sensed there was no demand in the line and it shut the water heater off. To test this, I went to the kitchen and turned the kitchen sink faucet all the way to the hot side and then turned it on so that I got a small flow of water. I waited for the water to get hot to be sure the hot water heater was working. Once it was hot, I left it running to keep demand in the line and then I went to the shower and turned the faucet on. When the water got hot I started feathering the control towards the cold side and soon I had warm water. So I think I'm right in that the sensor in the hot water heater was shutting the water heater off when the demand in the shower was lowered to a certain point when I was trying to adjust the water temp in the shower.

So now I can get warm water, but it means I have to leave the hot water running at another fixture in the house to create a false demand in the system so the hot water heater doesn't shut down. Is there a way to adjust the senor in the hot water heater so that it will stay on when I'm using the shower only, so I don't have to waste water by running another faucet when I want to take a shower?