Does a tankless unit suit your house?
Tankless sizing is not about gallons. It is about how much water must be heated per minute and by how many degrees. Add up the fixtures likely to run at once, then compare to the flow rate the unit can deliver at your incoming water temperature.
Cold groundwater needs a bigger temperature rise than warm water, so the same unit performs differently in January. A plumber calculates this on site instead of trusting a brochure number.
| Requirement | Gas tankless | Electric tankless |
|---|---|---|
| Fuel or power | Larger gas line, often bigger than a tank heater needs | High-amperage circuit, panel capacity checked |
| Venting | Sealed, special vent materials, side wall or roof | None |
| Condensate | Drain needed on condensing models | None |
| Water supply | Adequate pressure and flow, service valves | Same, plus incoming temperature in mind |
| Best fit | Larger households, high flow | Small loads, point-of-use, sometimes as add-on |
Flushing and descaling a tankless heater
Minerals in water settle out when it is heated. In a tankless unit, they coat the heat exchanger and narrow its small passages. The result is lower flow, hotter-than-set spikes, noise and eventually error codes.
A flush circulates a descaling solution through the unit and then rinses it. Service valves on the water lines make that possible, so a unit installed without them needs valves added first.
How often is a manufacturer question. Follow the manufacturer's schedule in your manual, because it differs by brand, model and water quality. If you cannot find the manual, give the dispatcher the model number and we can look up the requirements.
Worth knowing about local water
Do not assume your water is soft or hard. Ask the Merchantville Pennsauken Water Commission or New Jersey American Water for the latest annual water quality report, and test a sample from your own tap. Scale can change from street to street, so the report only tells part of the story.
Find your schedule
Read the manual for the flush interval and the approved solution.
Isolate the unit
Turn off gas or power and close the service valves.
Circulate the solution
A pump moves it through the heat exchanger for the time the maker specifies.
Rinse and restart
The unit is flushed clean, the filter is cleared, valves are opened and a test run confirms flow.
Tankless due for a flush?
Give the dispatcher the model number and what the unit is doing. A plumber can set up a descaling visit.
Error codes, beeping and lukewarm water
Tankless units report faults through codes, and a display or beep tells you something is off. The meaning of a code changes by brand, so look it up in the manual, then tell the dispatcher the number. Do not open the cabinet or bypass safety parts yourself.
Ignition or flame faults
Often a gas supply, a dirty sensor or a failed igniter.
Exhaust and venting faults
A blocked or damaged vent trips the unit for safety.
Flow and scale faults
Low flow or overheating often traces back to scale or a clogged filter screen.
Leaks
Water from the cabinet or a connection means shut off the water and power and call.
Installing or retrofitting a tankless unit
A retrofit replaces a tank with a wall-hung unit, so the gas line, vent and pipework change. A new install in a remodel can place the unit where it vents most easily. Either way, the plumber checks the gas line size, the vent path and the condensate route before you order.
If you are weighing tankless against a tank, see our water heater installation planning page, and if your old tank has failed, water heater replacement explains that decision.
Condensing gas models also drain acidic condensate, which needs a neutralizer or a safe drain path. Electric models skip the venting but demand a heavy circuit, so a full panel can rule them out. Houses in Pennsauken, NJ with 1960s-era panels deserve a capacity check first.
Water quality in Pennsauken, NJ and your tankless heater
Most Pennsauken addresses are served by the Merchantville Pennsauken Water Commission, which draws from wells in the Potomac-Raritan-Magothy aquifer. A few addresses are on New Jersey American Water, so check your bill.
The practical step is the same either way. Read the annual report, test your tap, and let those results shape how closely you follow the flush schedule.
Source type: Merchantville Pennsauken Water Commission public pages
What affects the price of tankless service and installation
A flush and a full retrofit are very different jobs, so the price depends on which one you need.
You describe the unit by phone, then the plumber confirms on site. You receive a clear price before work starts.
Before any retrofit visit, write down the number of bathrooms, the fixtures that run together and how long the wait for hot water feels at the farthest tap. Those three notes let the plumber size the unit more accurately than any chart.
Have this ready for the visit
These details speed up service.
- Model and serial number from the label
- The manual, or the brand name
- Any error code and when it appears
- Your last flush date, if any
- Photos of the unit, vent and gas line
Thinking of going tankless?
Call to talk through sizing, gas line and venting before you buy a unit.
Standards and rules behind this advice
Gas tankless units are listed to ANSI Z21.10.3, and the manufacturer's installation instructions set the venting, gas supply and clearance requirements. Department of Energy sizing guidelines work from flow rate and temperature rise, which is the math a plumber should show you.
Tankless questions, answered
Follow the manufacturer's schedule in the manual. It varies by brand, model and water quality. If water is scale-prone, plan on checking sooner, and ask us if you lost the manual.
Scale narrows the passages and insulates the heat exchanger. You may see reduced flow, uneven temperatures, noise and error codes, and eventually a failed part.
Yes, if too many fixtures run beyond its flow capacity. The unit then cannot heat enough water by the needed amount. Sizing to your peak demand avoids it.
Often. Tankless gas units draw more fuel at once, so the pipe size and run length must be checked. The plumber measures it before ordering.
Look the code up in the manual and note the number. Check the power or gas supply. If it persists, call with the model so a plumber can bring the right parts, or see water heater repair.
Yes. Customers in Cinnaminson and other towns near Pennsauken are served from the same 24/7 line, so give the dispatcher your address.
Condensing gas models do, since they make acidic water as they cool exhaust gases. Non-condensing and electric units do not. The plumber checks your model and plans a drain or neutralizer if needed.