My hot water goes cold in the middle of a shower
That sentence is how most homeowners describe a tankless problem. The unit may be scaled up, the flow may be too low to trigger it, or a sensor, fan or igniter may have failed. A plumber has to look at the heat exchanger and the error history to know which.
It is also what happens with an undersized unit when two showers run at once. The fix there is not a repair at all but a better match between the heater and your household.
Flushing and descaling a tankless heater
Scale is the leading reason tankless units lose performance. Minerals in the water bake onto the heat exchanger and narrow its passages. The unit then works harder to deliver the same flow and may overheat or shut down.
A flush connects a small pump and hoses to the service valves on the unit and circulates a descaling solution through the heat exchanger. We then rinse it, clean the inlet filter, and test the flow. Units installed without isolation valves need those added first.
Before the flush
We read the error codes, check the inlet screen and confirm the isolation valves open and close.
During the flush
Descaling solution circulates through the exchanger until the returning liquid stops showing scale.
After the flush
We rinse the unit, restore flow, and test outlet temperature at a faucet.
Your Lake Michigan water comes through the Village system, and the Village report does not print a hardness figure. Test your tap or ask the Village for its annual water quality report so you know what the exchanger faces.
Gas, venting and safety
Gas tankless units need correct venting and an adequately sized gas line. If you smell gas, leave the house, move a safe distance away, and call Nicor Gas on 888-642-6748 or 911 first. A unit that shuts down repeatedly or shows a combustion error should not be reset over and over.
When a tankless unit makes sense
| Good fit | Needs a closer look |
|---|---|
| Small households or wall-hung space needs | Large families with many overlapping showers |
| Existing gas line of adequate size | Gas line that cannot carry a larger load |
| Venting path available to the outside | Interior closets with no vent route |
| Owners planning to flush the unit on schedule | Owners unlikely to maintain it |
We check gas size, venting and panel capacity on a site visit before recommending a unit.
If you are weighing it against a standard tank, our water heater installation page explains the planned options. A tank that has failed and needs a fast swap is covered under water heater replacement.
Installing a tankless heater in an older Woodridge home
The median Woodridge home dates to 1980, and roughly seven in ten were built before 1990. Those houses were piped for a tank. A tankless swap often means a new vent, a bigger gas line, a condensate drain and an electrical outlet for the controls.
Woodridge requires a permit and final inspection for a water heater, so tankless installs are permitted too. Ask Community Development at 630-719-4750, or read the Village permit FAQ.
January lows average about 19 degrees at the nearest weather station, which matters for cold incoming water. The colder the water, the more work the unit does, so a unit must be sized for winter, not summer.
Common tankless problems
| Symptom | Common cause | What we do |
|---|---|---|
| Lukewarm output | Scale or low flow | Descale and test flow |
| Cold sandwich, hot then cold then hot | Short run times between uses | Check recirculation and flow thresholds |
| Error code on the display | Sensor, igniter, vent or flow fault | Read the code and test the component |
| Unit shuts off mid-use | Overheating from scale or blocked vent | Flush and inspect the vent |
| Water leak at the unit | Loose connection or failed valve | Replace the fitting or valve |
For leaks and part failures on any heater, our water heater repair team handles the diagnosis. Neighbors in Downers Grove get the same service.
What affects the price of tankless work
Installs and flushes are different jobs, and each varies with the house. You get a clear price before work starts.
Insurance rarely covers maintenance or planned upgrades. Policies differ, so ask your agent if a failed unit damaged your home.
Venting, gas sizing and water connections all fall under the plumbing code, so expect a permit. The Village of Woodridge has adopted the Illinois State Plumbing Code, and permitted work is inspected against that standard.
Questions we hear
Usually scale, low flow, or an undersized unit. A flush and a flow test tell us which.
It depends on your water and use. Test your tap, ask us on the phone, and follow the maker's guidance for your model.
Often yes, if the gas line, venting and electrical outlet support it. We check these on site.
Yes. Tell us the make and model when you call and we will say whether we can service it.
Yes. The Village requires a permit and final inspection for a water heater.
Leave first and call Nicor Gas on 888-642-6748 or 911. Do not reset or relight it.
Yes. Landlords and managers can call about one unit or several.
If your hot water has already stopped, a repair visit may sort it before you consider a new unit.