Tankless Water Heater Repairs

Tankless Water Heater Repair

Highland Park’s Local Plumbers, Rooted in the Trade Since 1960

When a tankless water heater stops delivering hot water during an Illinois winter, it needs attention fast. At Little Tommy's Plumbing Shop, Inc., we’ve been handling tankless water heater repair in Highland Park and across Lake County’s North Shore communities since 2009. Our family has been in the plumbing trade since 1960, and our owner, Tommy Mahoney, began his apprenticeship in 1989. That depth of hands-on experience means we’ve diagnosed and repaired many of the failure modes these systems develop.

Tankless water heaters heat water on demand rather than storing a preheated supply, which makes them efficient but dependent on specific components: heat exchangers, flow sensors, gas valves, and ignitors. When any one of those parts fails, output can drop fast. Our team is fully licensed and insured in Illinois, including State of Illinois backflow certification, and we carry the tools on every service vehicle to diagnose and address most issues in a single visit. For tankless water heater repair and our full range of water heater services and Highland Park plumbing services, we’re the local team to call.

Our plumbers in Highland Park, IL are available by phone at (847) 443-9115, or you can contact us online.

Signs Your Tankless Water Heater Needs Repair

These systems rarely fail without warning. If you notice any of the following, call a licensed technician rather than wait and see.

No hot water or insufficient hot water: Cold or lukewarm water when the tap should run hot points to a problem at the component level. The cause could be a failed heating element, a gas supply interruption, or ignitor failure. Whether your unit is gas or electric, don’t wait to have it looked at.
Visible leaks at the unit or connections: A leak at the base or around connection points isn’t minor. Unaddressed moisture can damage internal components and turn a repairable problem into a replacement recommendation.
Poor hot water pressure: Weak flow from hot taps can signal a clogged inlet filter, a mineral blockage inside the heat exchanger, or an internal flow restriction. It’s often an early indicator of scale buildup, which is common in homes throughout Lake County.
Strange noises from the unit: Gurgling, hissing, screeching, or grating sounds typically point to scale accumulation, loose internal components, or mechanical wear. Turn the unit off and call a technician promptly if you hear any of these.
Rising energy bills with declining performance: Tankless heaters are designed to be more efficient than tank units. If your bills are climbing while your hot water output is dropping, a failing component or significant scale buildup may be the cause.
Error codes on the digital display: Modern tankless units show error codes when something is wrong. These codes help our technicians identify the specific fault quickly rather than working through a broad diagnostic process.

What Little Tommy's Plumbing Shop, Inc. Brings to Every Repair Call

We handle both gas and electric tankless water heater repairs for residential clients throughout Highland Park and the surrounding North Shore communities. Our technicians explain exactly what they find, walk you through available options, and present a clear recommended course of action before any work begins. You’ll receive an itemized estimate upfront, and nothing starts until you’ve approved it.

Our service commitments are straightforward. We offer affordable financing solutions so budget constraints don’t delay a necessary repair. We provide warranties on all our services, and our Saver’s Club gives members priority scheduling for repairs and maintenance year-round. Our 100% satisfaction guarantee means we’re not finished until you’re satisfied with the work. We’re BBB-accredited since 2013, active in the Highland Park Community Foundation, and members of the Highland Park, Deerfield, and Highwood Chambers of Commerce. Because a tankless failure doesn’t wait for business hours, we’re available 24 hours a day, 7 days a week, including weekends and holidays. Calls are answered by a person at any hour, and our technicians have reached customers in as little as 30 minutes from the first call.

Call (847) 443-9115 anytime to speak with our Highland Park plumbers, or contact us online to schedule a visit.

How Highland Park’s Hard Water Affects Tankless Systems

Highland Park’s water supply comes from Lake Michigan and carries measurable levels of calcium and magnesium. Inside a tankless system, those minerals accumulate on the heat exchanger over time, forming a layer of scale that reduces how efficiently the unit transfers heat to the water passing through it.

As scale builds, the system works harder to reach the same output temperature, which can increase energy consumption and accelerate wear on internal components. This is one of the most common causes of performance decline in tankless units across Lake County and the North Shore. Annual or biannual descaling flushes help prevent that accumulation from progressing to the point where it can cause component damage or lead to a replacement recommendation.

What to Expect During a Tankless Repair Visit

Before we arrive, you’ll receive an en-route notification and a clear arrival time estimate. The visit starts with a visual inspection of the unit and its connections, followed by reading any stored error codes on the display panel. From there, the technician tests water flow and temperature output, identifies the root component failure, and confirms system performance after the repair is complete.

Gas-fired tankless systems require checking gas pressure and combustion components. Electric units require testing heating elements and electrical connections. Both demand licensed technicians familiar with the specific system type. Our service vehicles are fully stocked so that most repairs can be completed without a return visit. Customers have documented successful diagnosis and resolution of tankless issues that previous plumbers were unable to fix, including cases where another contractor had already attempted the repair.

Repair or Replace: Making the Right Call

Not every failing tankless water heater needs to be replaced, but not every struggling unit is worth repairing. Tankless systems can last up to 20 years with proper maintenance, significantly longer than traditional tank units. As a general guide, repair tends to make sense when the unit is under 10 to 12 years old, the problem is isolated to a single component, and the repair cost is well below half the price of replacement.

Replacement can become more cost-effective when a unit is older than 15 years, has needed repeated repairs over a short period, or can no longer meet the household’s hot water demand even when functioning correctly. Our technicians explain what they find, walk through the available options, and give honest guidance on which direction fits your specific situation. We handle both tankless water heater repair and new tankless installation, so we can support whichever path makes sense for your home and budget. The goal is an informed decision, not a pushed sale.

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Your Neighborhood Plumber

You Can Count On Us!

“I recently had a plumbing emergency and was incredibly impressed by the service I received. Little Tommy's plumbing was remarkably quick to respond to my initial call and dispatched a technician promptly. Their team was not only efficient in diagnosing and resolving the issue but also maintained a remarkably clean workspace throughout the process. Furthermore, I found their technician to be exceptionally friendly and professional, making a stressful situation much more manageable. I would highly recommend their services for any plumbing needs.”

- Megan S.
I highly recommend Jordan and Little Tommy's.
“It was a pleasure to meet Jordan. He arrived in time. He is friendly, polite and respectful. He solved my problem quickly and explained my options to me. I highly recommend Jordan and Little Tommy's.”

- Deena F.
Always happy with my interactions with Little Tommy's
“Always happy with my interactions with Little Tommy's. Highly, highly recommended. One time when my sump pump backup failed, Tommy was able to face-time me on a Sunday to help diagnose the problem. Last week when my Water Heater was leaking, Tommy was able to come out in 30 mins to quote me a replacement and we were back up and running within the next day. Again, they are highly recommended, and would use again!”

- Dustin G.
No Nonsense Quote
“There is a lot to be said about supporting local folks. And over and above that fact Little Tommy's was OUTSTANDING in all aspects of our encounter. From the friendly young lady on the phone, to the quick response, to Jordan the total professional who accomplished the installation. The price was fair and there was a no nonsense quote. I feel totally confident in recommending Little Tommy's.”

- Mike L.
Great company. Reasonable price. Would highly recommend for plumbing repairs.
“Jordan did a great job. Our cast iron pipe going out from our house to the sewer line had broken. We had a backup of the sewage water inside our bathroom on the first floor and the basement. Little Tommyâ€™s Plumbing company fixed the issue by removing the part of the cast iron pipe that was broken. It was about 4 feet under the ground and installed a PVC pipe. They also obtained the village permit for this work on an expedited basis. Great company. Reasonable price. Would highly recommend for plumbing repairs.”

- Sudhir P.
Best company around here.
“Little Tommy's sent Josh to fix my sink. Delightful experience and result. Josh fixed the problem immediately and then imparted very useful advice and pointers to avert plumbing issues. Best company around here.”

- Steve O.
Great Customer Service & Follow Through
“Tom from Little Tommy's provided me a thorough and timely quote as I am selling my house. The best thing is that he partnered with a tile and a glass company to provide a comprehensive quote. Great customer service and follow through. I would definitely recommend his service.”

- Michael W.
Their service exceeded my expectations!
“Tyler did a fantastic job! It is such a pleasure to do business with a company who is efficient, fast in an emergency, and is trustworthy. I was left feeling they were completely fair and their service exceeded my expectations!”

- Linda S.
Correctly Diagnosed
“They correctly diagnosed and repaired our issue after the first plumber ghosted us and the flooding began again.”

- Craig N.

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