Areas We Serve

Areas We Serve

Why Does My Tankless Water Heater Turn Cold Mid-Shower?

Many homeowners experience “cold water sandwich” problems with tankless systems. While the issue can be annoying, the good news is that there are clear reasons behind it and dependable solutions to get your hot water flowing consistently again.

At 2 Sons Plumbing Everett, we’ve helped countless families troubleshoot and repair tankless water heater problems. Whether it’s something small like a cleaning or a bigger issue requiring a valve repair, our licensed plumbers know how to get your hot water back on track.

Common Reasons Tankless Water Heaters Go Cold

Tankless systems work differently than traditional tanks—they heat water on demand. But that means when something disrupts the flow or heating process, you’ll feel it right away. Here are the most common causes we see in Everett homes:

Low Water Flow

Tankless heaters need a certain level of flow to stay engaged. If the flow dips too low—say when someone flushes a toilet or runs another faucet—the burner can shut off, sending cold water your way.

Mineral Scale Buildup

Everett’s water often contains minerals like calcium and magnesium. Over time, these build up inside the unit, coating heating elements and reducing efficiency. This can lead to fluctuating temperatures and shorter bursts of hot water.

Mixing Valve Issues

Many systems use a mixing valve to blend hot and cold water safely. If the valve is out of balance or failing, it can send unexpected blasts of cold water right into your shower.

DIY Steps You Can Try

If your tankless water heater is turning cold mid-shower, here are a few simple things to try before calling for help:

Run another faucet. Increasing water flow helps keep the burner engaged.
Check the thermostat. Make sure the temperature is set to about 120°F for steady performance.
Descale the heater. Flushing the system once a year removes mineral deposits and keeps water moving smoothly.

These steps may fix minor issues, but if the problem keeps happening, it’s time for a professional inspection.

When to Call a Plumber in Everett

Some warning signs mean it’s best to shut the system down and get expert help right away:

Error codes on the display screen
A gas smell near the unit
Frequent cold water bursts despite cleaning and adjustments
Water that never heats up at all

At 2 Sons Plumbing Everett, we use specialized tools to diagnose tankless water heater problems. From descaling ($250–$500) to repairing or replacing valves, we’ll find the right solution to restore reliable hot water for your family.

Reliable Tankless Water Heater Repair in Everett

Cold showers are no fun, and with a properly working tankless water heater, you shouldn’t have to deal with them. Whether the issue is as simple as mineral buildup or as complex as a failing valve, our licensed plumbers know how to pinpoint the cause and fix it for good.

Call 2 Sons Plumbing Everett today at (206) 487-1757 if your tankless water heater is running cold mid-shower. We’ll respond quickly, restore your hot water, and give you peace of mind knowing your system is in expert hands.

2 Sons Plumbing, Electrical, Heating & Air

4.9

Based on 3586 reviews

review us on

Emily Speakman

22:53 16 Feb 26

Had issues at home with water backup. Dave was prompt, professional, and genuinely kind. He communicated between myself and my landlord, explaining the issues and next steps. He quickly put an interim solution in place and outlined the long-term needs. Felt super reliable and easy to work with — highly recommend 2 Sons Plumbing.

Emily Speakman

22:53 16 Feb 26

Frank Church V

22:16 15 Feb 26

We contacted these Plumbers on a Friday using Yelp quotes, and they were the fastest to reply and the fastest to engage with us when we had questions. We felt that warranted to give them the opportunity to give us the first consultation. Sometimes we get multiple consults if we get any icky feeling from the people doing it. We didn’t feel that way with this company.

Our toilet was leaking, and we expected we probably could use a new one. But wanted a professional estimate and options.

We got hooked up with their team to schedule it and they were able to give us a time only a day out. We asked for a 8-1pm window and received automated text and a formal phone call from a dispatcher saying how far out the plumber technician was.

The plumber who showed up was named Carey. We also a received a picture of him before he arrived for safety concerns which I thought was a good touch of care from the company. Carey was lights-out the best guy we could have asked for.

He showed up within the approximate eta and was kind, gracious, considerate of our space and gave us a myriad of options. He quoted us prices that felt quite fair, and we chose the option where he removes the toilet and chooses a toilet for us: though we talked about the various options beforehand.
All and all he left for 30 min to get the toilet: and returned to install it. Installation was complete within another 30 minutes.

He was so good man. And we just felt like this is how service and care and things should be in this world. It’s always refreshing when you get that. Because so many outfits just: make you regret everything.

The work was quick, professional, and he was happy to be there and gave us information every step of the way that we respected and appreciated.

We will use this company in the future. You earned our respect and business.

Frank Church V

22:16 15 Feb 26

Sitong Liu

07:46 04 Feb 26

I initially hired this company to address a leak in my water service line. Due to repeated misdiagnosis and unsuccessful repair attempts, the work ultimately escalated into a full water service line replacement, resulting in a final cost far higher than what I had initially expected. While the replacement is now completed and functioning, the overall experience was frustrating and poorly managed.

From the start, pricing and expectations were unclear. I was told repair costs couldn’t be determined until excavation, yet on the day of work—before anything began—I was asked to sign for a high fixed repair price based on assumptions that were never discussed during the estimate.

The first repair attempt failed, and the leak clearly continued. No further investigation was done, I was required to pay in full, and I was told a discount would only apply if I committed to a full water service line replacement the same day, before the issue was properly resolved.

After paying for a second leak detection myself, the original leak was confirmed to still be present. Management involvement was requested but delayed, and during a follow-up visit I was asked to sign a new agreement stating the work was only a “repair attempt” with no warranty, despite the original repair being sold as warrantied.

I later proceeded with the water service line replacement based on specific assurances about the final cost, but the estimate I received did not align with those assurances. Throughout the process, I had to make multiple phone calls and send repeated emails over several days just to get responses.

While the final replacement works, the lack of technical competence, shifting pricing and warranty terms, and consistently poor communication made this an unnecessarily stressful experience. I would not use this company again.

Sitong Liu

07:46 04 Feb 26

DyAndreye Wray

20:14 03 Feb 26

Carey and Mycha came over to do some plumbing work at my residence and did an amazing job from beginning to end.
I appreciate the great communication and great service and it was done in a timely fashion. Thank you for the service & I look forward to doing business with you again!

DyAndreye Wray

20:14 03 Feb 26

Tanya Hines

18:09 02 Feb 26

Dave from 2 Sons Plumbing was fantastic! He arrived on time, quickly diagnosed the issues and turned out nothing needed to be fixed so was honest about that. And that’s appreciated! Very professional and Excellent communication! I will definitely be using 2 Sons Plumbing again for any plumbing needs and also I have already recommended to my parents! I will also be Highly recommending to my friends, family and acquaintances!

Tanya Hines

18:09 02 Feb 26

Ashley Arata

23:22 29 Jan 26

Carey and Micah came out on short notice when our tankless water heater started leaking unexpectedly. They were able to provide an extremely competitive quote on site and schedule us for installation the next day. We had some other pre-scheduled contractors in our home when they did the installation and they were extremely professional and courteous in making space for them to share space. I also appreciate how they cleaned up after work was completed. Overall wonderful guys and our second time using 2 Sons (once prior was to have a sewer line cleared) and we'd absolutely use them again. Thanks, Micah & Carey for the work!

Ashley Arata

23:22 29 Jan 26

Johnnie Williams

06:40 15 Jan 26

I want to start by saying that Jeff and the rest of the plumbing team are absolutely great. They are very knowledgeable, professional, and clearly know what they’re doing. The quality of their work is solid, and I never felt like I was dealing with people who didn’t understand their craft.

That said, the pricing is extremely high. I completely understand paying for quality and expertise, but the cost made it hard to move forward with them for future work. If their prices were more reasonable, they would 100% be the company I would use every time.

So if budget is not a concern, you’ll likely be very happy with them. But for those of us who have to balance quality with affordability, the pricing is something to seriously consider.

Johnnie Williams

06:40 15 Jan 26

Kizmit

01:40 03 Jan 26

I had a kitchen sink that started draining very slowly. Scheduling with 2 Sons was quick and easy. The technician arrived on time and was polite and friendly. Unfortunately, he was unfamiliar with the pipe configuration in my condo building and told me he was unable to get the cable through. He then provided me a written estimate for over $1600 to reconfigure the pipes. He stated the drain could not be cleared until that work was done. I was charged over $500 even though he was unable to do any work (got the cable down the pipe less than 5 feet before he gave up.) I called another plumber who came out a few days later and was able to use the cable to clear the drain (exactly what the plumber from 2 Sons said could not be done). I have emailed 2 Sons three times, explaining my concern and requesting a refund of the fee I paid, but am having difficulty getting anyone to respond to me. Overall, a very frustrating experience. I cannot recommend them based on this experience and lack of response.

Kizmit

01:40 03 Jan 26

Deann Minamino

22:05 02 Jan 26

We have used 2 Sons Plumbing quite a few times now and have never been disappointed! Courteous, professional, knowledgeable and efficient describes everyone from the office to the field teams! One of their team members, while here installing a sink fixture, overheard an estimate we were getting from a visiting sales rep for a project. Their team member (Carey) offered that the estimate was way over priced (by over $20k). We had 2 Sons price it out for us and they came in $23k less. We have a couple planned projects upcoming and plan to use them for that as well as any unexpected issues that arise. Just this week, they dispatched a team on NYE as our water heater broke. Once again, good price, courteous, professional and efficient! I/we are so pleased to have found this company! We highly recommend them! (NOTE/FYI: I, the posting party, copied this from my Yelp Review)

Deann Minamino

22:05 02 Jan 26

Ashley Dunn

21:37 01 Jan 26

Justin and Bryce were swift and thorough when we experienced an emergency leak in our daylight basement. They quickly identified the problem as a leaking water heater, provided a quote, and completed the work within just a few hours. The job included draining the old water heater, removing and properly disposing of it, and supplying and installing a brand-new unit. We are incredibly grateful that they came out on New Year’s Eve and ensured we didn’t start 2026 without running water. They also offered a great recommendation for addressing separate water damage caused by another issue. Highly appreciated and highly recommended

Ashley Dunn

21:37 01 Jan 26