Tankless Water Heaters
 

I changed out from a tank heater last year; seemed like a good deal from TECO with monthly no-interest payments. Right away, a couple times per month, the shower would go cold. Turned the faucet off and waiting for everything to heat up again and got hot water again. Thought it might be the shower valve, but then it started happening in our other shower. Finally had original installation plumber check it out and they agreed with me there was probably something amiss with the main circuit board, but the manufacturer said they would not agree with this part replacement. So the plumber left and again today the shower went cold. Has anyone else had this negative experience with a tankless water heater?

As I recall TECO is both a gas and electric company, so is the tankless water heater a gas or electric unit? I am GUESSING that the unit maybe cycling due to an overtemperature condition. Try an internet search on you make and model to see if others have reported the problem and any possible solutions.

Try running a little hot water into the sink as you are taking your shower. If the problem does not occur, the heater may be detecting low flow and shutting down. If that is the case, maybe change the flow restriction in your shower head. Just an idea.

Sounds familiar
 

Turn the hot water on in the shower then go and watch the unit. If it shuts down with the water flowing it should flash a code. I’ve had one up north, for 10+ years and about a year ago mine did the very same thing. After getting hot water and stepping into the shower 2-4 minutes later the water turned cold. After seeing the code and checking the manual it said the problem was soot on the AFR (air-fuel-ratio) device. I removed it and rubbed it lightly with emery paper and reinstalled it. No more problems! Mine was natural gas fired and was always cleaned on a regular annual basis.

It's gas. I set my shower valve so it draws 3/4 to 1 gpm from the hot water heater (based on the flow meter in the unit). It's minimum flow requirement is 0.4gpm so we draw double that or more. To draw even more, I decreased the output temp on the unit, meaning we have to get more hot water flow to achieve the same temperature in the shower. Amazingly, this caused the problem to occur much more often, which refutes low-flow as a cause! Consequently, I figured it must be related to how the heater cycles on/off during use (to maintain the set output temperature) and must be faulty in not properly cycling back on sometimes. But the company (State) would not authorize the replacement of the motherboard where all the sensors and circuits to do the cycling are located.

I got the same deal from TECO and installed by Mike Scott the installation and hot water heater has a warranty. I would reach out to TECO.

I had a tankless and regretted it. Nothing but problems. Switch back.

Dang, sorry you're dealing with this. I thought the extra cost of tankless was a deterrent, now I see there's more issues at hand! Good luck, especially getting it fixed under warranty. Don't let them scam you out of your fair due.

I have one bought from lowes works great it is electric and needs 2 40amp breakers. Had to replace it one time in 15 years.

Tankless water heaters are the way to go, why constantly heat water in a tank all day long when you don’t need the water? The tankless hot water is not an instant hot water device, you still have to wait many seconds/minutes for the hot water to get to the faucet. Also, if you stop the water filling up the tub and restart filling up the tub again, you will get cold water for many seconds/minutes again which is all normal. If you want instant on hot water, then you need a recirculating pump to make this happen.

I had a tankless water heater in a home I had built over 30 years ago, the only problem I ever faced was an oversized jacuzzi and I do mean oversized. I'm sure tankless water heaters have improved since then, if you are having a problem get somebody in to check what it is. There is no reason that a tankless water heater cannot handle the size of a home here in TV.

My tankless unit (electric) also has a *maximum* flow rate which, if reached, errors out and everything goes cold. I don't know if that is what is happening to you or not - don't know if gas units act the same way. My unit has worked great otherwise for the last 5 years. I just can't open the tub valve (the largest flow in the house) full blast. But I also didn't order the biggest unit. Mine was a 15kW.

The water volume restriction device in the actual shower head is usually part of the problem. Removed them from both our showers and no more problems.

My Rheem (gas) started doing that a while back while still covered by home warranty.

As someone above mentioned, the heater was not seeing enough water flow and would shut off the burner.

It was due to the “water saving” restrictor in the shower head .

Once I removed the restrictor from the shower head to allow a better flow, the problem disappeared !! Now I can better control the flow at the head.

Another tip regarding the length of time it takes to get hot water to the furthest faucet ….usually the master shower head……

Tip: when ready to shower , run your shower on full hot AND one of your bathroom faucets on full hot as well.

With the restrictor removed from the shower head we get hot water ready to go in about 45 seconds…..no BS