Why tankless units need a flush
A tankless heater heats water as it passes through a heat exchanger, and the passages inside are narrow. Mineral scale that builds up there restricts flow, lowers the temperature and makes the unit work harder. Flushing and descaling is the most common reason people call us about tankless units.
The process runs a descaling solution through the unit with a pump while the heater is isolated from the house. Done on a regular schedule, it clears scale before it hurts performance. Done late, scale can build up enough that a unit runs hot, overheats or shuts down with an error. Call (630) 822-9290
Isolation valves on the cold and hot lines make flushing much easier. If your unit was installed without them, we can add them, and every flush after that goes faster.
How often to flush
The right interval depends on your water and how much hot water you use. Many manufacturers call for a yearly flush, and some units show a service reminder on the display. Check the manual for your model, since skipping the maintenance it requires can cause trouble with warranty claims.
Hoffman Estates gets Lake Michigan water bought from the City of Chicago. The Village's 2025 Water Quality Report does not print a hardness figure, so we do not assume how fast scale forms in your unit. We check the exchanger and the flush water instead, and tell you what we see. If scale looks heavy, a water softener or filter may be worth a conversation.
Common tankless problems
Most tankless calls fall into a few groups. A lack of hot water, water that swings hot and cold, an error code on the display, a unit that will not ignite, and a unit that shuts off after a short run are all common. Each one has several possible causes.
| Symptom | Common cause | Typical step |
|---|---|---|
| Lukewarm water | Scale in the heat exchanger | Flush and descale |
| Hot then cold swings | Low flow or dirty inlet filter | Clean filter, check flow |
| Error code | Ignition, venting or sensor issue | Read the code, then test |
| Unit will not ignite | Gas supply, vent or igniter | Safety check first |
| Shuts off mid-use | Overheat limit or blocked exhaust | Inspect vent and exchanger |
Do not keep resetting a gas unit that fails to light. If it smells like gas at any point, leave the building and call the Nicor Gas emergency line or 911 from outside, then call us.
Reading error codes
Tankless heaters display numeric codes that point to a system, such as ignition, air flow, water flow or temperature. The code is a starting point and not a diagnosis. A venting code, for example, might come from a blocked pipe, a failing fan or a sensor.
Send us the code and the model number and we can say what is likely before we arrive. A clean inlet filter, a flush or a vent check solves a lot of codes. Some require a part, and we explain the cost before we replace anything. (630) 822-9290
Switching from a tank to tankless
Replacing a tank with a tankless unit is a bigger job than swapping one tank for another. Gas models usually need a larger gas line, special venting and a power outlet. Electric models need a lot of amperage, which can mean a panel upgrade. Both need the plumbing set up for the new connections.
Many homeowners who want endless hot water find the change worthwhile, and others find the upfront work does not fit their house. We walk you through both sides, including the tank option in water heater installation. If your current tank has already failed, water heater replacement covers the quick-turnaround path.
A vent that has to move is one of the larger parts of a conversion. We note it up front so the price on the phone matches the job. Call (630) 822-9290
Nicor Gas rebates for tankless in 2026
For Nicor Gas customers, the 2026 Energy Efficiency Program lists $150 for a whole-home tankless water heater with a UEF of 0.95 or higher and a capacity of 75 MBTUH or less. The heater must be installed between January 1 and December 31, 2026.
You apply within 90 days of installation or by January 31, 2027, at apply.nicorgasrebates.com or by calling 877-886-4239. Nicor sets the rules and can change them, so confirm the details before you buy. We can help you check whether a particular model fits those numbers.
Heat pump and hybrid questions
We get the occasional question about hybrid heat pump water heaters, including the service of units made by A. O. Smith. These are tank-style units with a heat pump on top, so they sit between a standard electric tank and a tankless unit. They need room, airflow and a condensate drain.
If you have one that needs service, call with the make and model. We will tell you what we can look at and what may need the manufacturer.
Permits and code in Hoffman Estates
The Village of Hoffman Estates covers water heaters under one permit handout, and the Village fee handout lists $50 for a water heater permit. A final inspection is required, and the Village does not do same-day inspections. Venting, relief piping and shut-off valves are among the items the inspector checks.
Gas work and venting should be done by a licensed and insured plumber. Illinois licenses plumbers through IDPH, and the Village follows the Illinois Plumbing Code. We do not recommend a do-it-yourself tankless install, because gas, venting and electrical errors are the kind that hurt people. (630) 822-9290
Manufacturer installation instructions are the standard for a tankless unit's gas line size, vent material and clearances. The Village handout also asks for manufacturer clearances, so a vent run that departs from them can fail the final inspection.
If your tankless unit is leaking or has stopped working in the middle of winter, our 24/7 line is open, and water heater repair covers what to do while you wait.
What changes the price
We give the price by phone before work starts. Tell us the brand, the model and any code on the display, and we will say what we need to know before quoting. Call (630) 822-9290
Tankless water heater questions
Many manufacturers suggest yearly. Check your manual, and tell us how the unit has been performing.
Scale in the heat exchanger is a common reason. A clogged inlet filter or low flow can also cause it.
Yes, in most cases. They make flushing much easier and are worth adding if your unit did not come with them.
It points to a system such as ignition, venting or flow. Send us the model and code and we can say what is likely.
It depends on your home. Endless hot water and no standby tank are the upside, while the upfront work in gas, venting and electrical can be larger.
For 2026, Nicor lists $150 for qualifying whole-home tankless units installed in 2026. Check their rules before you buy.
We can look at them. Call with the make and model so we can say what we can handle.
Planned service is scheduled by phone. Our 24/7 line takes urgent calls any time, and we will say what is possible.
When you are ready to book a flush or ask about a conversion, Call (630) 822-9290 or dial (630) 822-9290.