[neilbcox]

Originally Posted by Marathon Man

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.

Our 3 month old new home in Newell had the problem of hot water turning into cold water during a shower. The installation plumbing company came out and fixed our problem yesterday!

The problem with the gas tankless water heater turning off during a shower was the low water flow…they require an increased flow to operate. The plumber opened up the shower head water flow restricter. It comes with restricter to reduce your water consumption!

Problem resolved!

[OhioBuckeye]

Originally Posted by dougawhite

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?

I have a Tankless Water Heater but it’s outside, now isn’t that stupid. I babysit it all winter. OK, back to your question, I have the same issue but the only way I get hot water is to run the hot water for a couple of mins. until it start to run hot. Then you never run out of hot water, even if you run it for 2 hrs. I don’t agree with the person that said it’s in your circuit breaker box, unless it kicks out your breaker & you have to reset it. Run your hot water for a couple of mins. & see if you get hot water then otherwise whoever sold you the Tankless Water Heater call them back. It’s not the breaker box unless it’s kicking out your breaker for Water Heater!

[mark100]

Originally Posted by dougawhite

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?

Over 4-5 years ago we installed a Rinnani Tankless Water Heater. We use natural gas. Never had an issue. Are you using electric. If you do not get satisfaction call the home office for the manufacturer.
The only complaint we have is it takes about 1 minute to get hot water as the pipes are in the ground under the slab.
We can run 7 gal a minute for as long as the faucet is turned on.
Good luck

[Hape2Bhr]

Originally Posted by dougawhite

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?

If the water only goes cold using your showers, and not when filling a tub or using your sinks you need to remove the restrictors in the shower heads. If the water goes cold using the tub or sinks, I would check the screen on your inlet valve. If the plumber turned off your water service to do the install, some dirt may have been kicked up in the lines when the water was turned back on. There is a stainless steel screen on the feed (inlet) side of the heater.

[trishaf]

If you have a mixing valve that was not change, it most likely is the problem. You can have it changed or removed but be warned without it, the water will get scalding hot and you need to careful mix enough cold with the hot.

[Nana2Teddy]

Originally Posted by dougawhite

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?

This was happening to many of us new homeowners down here in DeLuna a few months ago. It ended up being an actual faulty part that needed replacing. It wasn’t due to flow restriction. Mike Scott, the company that installed the tanks here, was sent by warranty when this happened to us, and at first they wouldn’t admit what the issue was because we didn’t have an error code to show them. But when I mentioned that this had happened to many homeowners in our village, and they had all shared what the issue was on Facebook, they finally admitted it was a faulty part. They replaced it and we’ve never had the issue again after several months. We still have our flow restrictors too… for now. We will be replacing all of our shower heads soon, and will remove all of the restrictors. I’m sorry I can’t remember the name of the part, and hubs is up at Savannah center at the moment setting up for this weekend’s model train club show, but I will update here when he gets home.

[Marmaduke]

Originally Posted by pikeselectric

Hi there! Yikes. It sounds like a real nuisance. Sorry to hear about this. First thought, wondering how the unit was wired to the electrical panel? Proper installation and line ran for the unit per its specifications? We would be happy to evaluate this for you.
Also, any warranty through plumber/manufacturer to replace the unit as "defective" if it is internally bad? Looking forward to speaking with you. You are welcome to message our page or email me directly (cnelson@pikeselectric.com)
- Casandra with Pike's Electric

OP, Just yesterday, we had a very good experience with Pike Electric.
Trustworthy. Professional. Very Knowledgeable.
I am a woman who felt very comfortable dealing with all of them, from Casandra at their office in Wildwood to the 2 electricians, who came into our home.
Maybe you should give Casandra a call, she's very proficient.

[rrdsg]

There are tankless models that are instant hot. I get very hot water immediately from every output.

[pikeselectric]

Originally Posted by Marmaduke

OP, Just yesterday, we had a very good experience with Pike Electric.
Trustworthy. Professional. Very Knowledgeable.
I am a woman who felt very comfortable dealing with all of them, from Casandra at their office in Wildwood to the 2 electricians, who came into our home.
Maybe you should give Casandra a call, she's very proficient.

Hi there! Thank you so much for your kind words and recommendation. It is a pleasure working with you! I am here to assist
- Casandra with Pike's Electric 352-748-6251

[Altavia]

Originally Posted by Nana2Teddy

This was happening to many of us new homeowners down here in DeLuna a few months ago. It ended up being an actual faulty part that needed replacing. It wasn’t due to flow restriction. Mike Scott, the company that installed the tanks here, was sent by warranty when this happened to us, and at first they wouldn’t admit what the issue was because we didn’t have an error code to show them. But when I mentioned that this had happened to many homeowners in our village, and they had all shared what the issue was on Facebook, they finally admitted it was a faulty part. They replaced it and we’ve never had the issue again after several months. We still have our flow restrictors too… for now. We will be replacing all of our shower heads soon, and will remove all of the restrictors. I’m sorry I can’t remember the name of the part, and hubs is up at Savannah center at the moment setting up for this weekend’s model train club show, but I will update here when he gets home.

If there is an error code 11, The ignitors tend to be a cause. If handy, they are easy to change and available on Amazon.

Rheem PROTECH Ignitor Coil RTG20235C https://a.co/d/hwzmBCZ

There's also been problems with the cheap Chinese gas pressure regulators used during construction. You may have instances of hot, cold, hot water before they fail completely.

Since they are attached to the gas line, best to use a plumber like Mike Scott Inc. to replaced those. The regulator they use is much higher quality, replacement cost is under $200.

[dougawhite]

Update - The original issue of hot water going cold during showers has stopped occurring for the last 5 months. I can't explain why it is now OK, so sorry for the mystery...

[Maker]

Originally Posted by Altavia

If there is an error code 11, The ignitors tend to be a cause. If handy, they are easy to change and available on Amazon.

Rheem PROTECH Ignitor Coil RTG20235C https://a.co/d/hwzmBCZ

There's also been problems with the cheap Chinese gas pressure regulators used during construction. You may have instances of hot, cold, hot water before they fail completely.

Since they are attached to the gas line, best to use a plumber like Mike Scott Inc. to replaced those. The regulator they use is much higher quality, replacement cost is under $200.

A bad igniter will stop the unit from firing up at all. 100% cold, 100% of the time.
But if that is the issue for someone else, with a Rheem, then it's a simple task to swap. Trivial DIY and no plumber is needed because nothing is being touched with the gas or ware lines.