01Est. $1,400 - $2,900
Gas Water Heater Installation
40 to 80 gallon gas tanks on Atmos Energy gas, with the vent and sediment trap checked.
$3,800 - $7,500Estimated installed range for a tankless unitOur estimated range
24% - 34%More efficient than a storage tank at 41 gallons a day or lessU.S. DOE
8% - 14%More efficient at about 86 gallons a dayU.S. DOE
20+ yearsDOE's life expectancy, against 10 to 15 for a storage tankU.S. DOE
2.0 gpmWaterSense limit for a showerhead; bathroom faucets 1.5 gpmU.S. EPA WaterSense
Short answer
Tankless water heater installation in Rowlett swaps a storage tank for a wall-hung unit sized by flow rate. The U.S. Department of Energy puts these units at 24% to 34% more efficient for homes using 41 gallons a day or less, and 8% to 14% for heavy users. In Rowlett it is estimated at $3,800 to $7,500 because the gas line and vent usually change.
01The numbers
What the Department of Energy Actually Says About Savings
Tankless heaters save energy because they don't keep 40 or 50 gallons hot all day and night. The U.S. Department of Energy quantifies it by how much hot water a home uses: 24% to 34% more efficient than a storage tank for a household using 41 gallons or less a day, and 8% to 14% at about 86 gallons a day. The saving shrinks as use grows, because a busy household's tank loses less of its heat to standing time.
The same DOE page puts the life expectancy of most tankless units above 20 years, against 10 to 15 for a storage tank. Both numbers are favorable, and neither alone justifies the price. The estimated gap between a like-for-like tank ($1,400 to $2,900) and a tankless installation ($3,800 to $7,500) is $900 at its narrowest and $6,100 at its widest, so the saving has to be weighed against a real up-front premium.
| Storage tank | Tankless | |
|---|---|---|
| Estimated installed range | $1,400 - $2,900 | $3,800 - $7,500 |
| Life expectancy (DOE) | 10 - 15 years | More than 20 years |
| Efficiency vs a tank, light user (41 gal/day) | Baseline | 24% - 34% better |
| Efficiency vs a tank, heavy user (86 gal/day) | Baseline | 8% - 14% better |
02Sizing
Sizing a Unit by Flow, Not by Gallons
A tank is sized by what it holds. A tankless unit is sized by how much water it can heat per minute. The formula is short: output in BTU per hour equals gallons per minute times 500 times the temperature rise in degrees (500 comes from 8.34 pounds a gallon times 60 minutes). The U.S. EPA's WaterSense program caps showerheads at 2.0 gallons a minute and bathroom faucets at 1.5, and the federal maximum for a showerhead is 2.5.
Take a Rowlett morning with two showers and a bathroom tap running. At the federal maximum that is 5.0 plus 1.5, or 6.5 gallons a minute. With WaterSense fixtures it is 4.0 plus 1.5, or 5.5. With a 65-degree rise (55-degree water to 120, an assumption, not a Rowlett measurement), 5.5 gallons a minute needs 5.5 times 500 times 65, or 178,750 BTU an hour of output. That is close to the whole capacity of a large residential gas unit, which is why the sizing step decides the job.
03Winter
Why Winter Flow Is Lower Than the Brochure Says
The same unit delivers fewer gallons a minute when the water entering it is colder, because the rise is larger. DFW Airport's January normal low is 36.1 degrees and the normal high 56.5, and incoming water follows the ground, not the air, but it is still cooler in January than in August. Using an illustrative 180,000 BTU an hour of output:
| Temperature rise | Gallons a minute |
|---|---|
| 50 degrees (warm inlet) | 7.2 |
| 65 degrees | 5.5 |
| 75 degrees (cold inlet) | 4.8 |
| 85 degrees (very cold inlet) | 4.2 |
That is a drop from 7.2 to 4.2 gallons a minute with nothing changed except the weather. A unit that serves a household in July can run short in January, so we size for the cold month, not the warm one.
04What the house must provide
Gas, Vent and Wall: The Three Changes Behind the Price
The DOE notes that demand heaters usually need venting and gas piping changes. In practice that comes to a short list:
- Gas. A storage tank burns roughly 30,000 to 40,000 BTU an hour. A whole-house tankless unit can ask for 150,000 to 199,900. The line that fed the tank is often too small and gets upsized, sometimes back to the meter.
- Vent. A tankless unit gets its own vent, not the tank's old flue. Condensing models vent in plastic pipe and need a place to drain acidic condensate. Non-condensing models vent through stainless pipe.
- Wall and power. The unit mounts on the wall with the maker's clearances and needs an outlet for the controls and fan.
- Valves. Isolation valves let the unit be flushed of scale later, and they should go in the first time.
A fit check looks at all four before any quote is written, because skipping the gas line is the common way a tankless install disappoints. The conversion page walks through that job.
Need Tankless Water Heater Installation in Rowlett?
Tell us how many bathrooms and people you have and you get an estimated range on the call.
05Rowlett's water
Scale in a Heat Exchanger Is Hard to See and Easy to Fix
10.7 gpgNTMWD treated-water hardness in January 2015 (183 mg/L / 17.12). Sampled months in 2022 and 2023 ran 7.1 to 9.3.
Rowlett's treated water comes from the North Texas Municipal Water District, which calls it moderately hard because of the minerals in Lavon Lake. Its analysis tables show total hardness of 183 mg/L in January 2015 and 122 to 160 mg/L in sampled months of 2022 and 2023. Divided by the district's factor of 17.12, that is 10.7 grains per gallon in 2015 and 7.1 to 9.3 in the later months.
Water at that hardness leaves scale in a tankless unit's heat exchanger. The scale narrows the passages, cuts flow and makes the unit work harder, and it is the main reason a tankless heater without service valves loses efficiency in its first years. A descaling flush through the isolation valves about once a year is the maintenance that earns the DOE's 20-year figure.
06What it costs
Why the Range Runs From $3,800 to $7,500
The low end is a unit going where a tank was, on a gas line that is already big enough, with the old flue reusable as a chase for the new vent. The high end is a unit on a new wall with a longer vent run, a line upsized from the meter, a condensate drain and a new outlet. The unit itself is only part of either number.
We list each piece on the written quote, so you can see what the gas line costs against the unit and the vent. Where a quote lumps them together, ask for it split. The cost guide has a checklist of what a full quote contains.
07Power and outages
Tankless in a Power Cut
A gas tankless unit needs electricity for its fan, igniter and controls, so it stops when the power does, even though the fuel is gas. In February 2021 the Texas health department counted 246 deaths from Winter Storm Uri statewide, 22 in Dallas County, during outages that lasted days. If outage resilience is a priority, a standing-pilot gas tank keeps heating without power and a tankless unit doesn't. A small battery backup can run a unit's controls for a short time, and it is worth asking about.
08Who shouldn't
Households That Are Better Off With a Tank
A tankless unit isn't the answer for everyone. A one- or two-person household that uses 30 gallons a day gets the highest percentage saving, but it is a percentage of a small bill, and the extra $900 to $6,100 can take most of the unit's life to repay. A house whose gas meter can't supply 150,000 BTU an hour without a costly upgrade is a poor fit. A home with a long run to the far bathroom will still wait for hot water, because a tankless unit doesn't fix distance.
If your complaint is running out of hot water in a larger household, it is the strongest case for a tankless unit or a bigger tank, and the tank versus tankless guide compares them.
09Install day
What Happens on a Tankless Job
A tankless installation usually takes most of a day, against 3 to 5 hours for a like-for-like tank. The fit check comes first, then the old tank is drained and removed, the gas line and vent are run, the unit is hung and connected, the condensate and valves are fitted, and the unit is fired and tested at several taps with a thermometer. Texas requires installation for customers by a licensed plumber under the State Board of Plumbing Examiners, and we confirm Rowlett's permit requirement for each job.
10Near the shop
Gas Lines and New Builds Around Rowlett
Newer Rowlett communities are where gas lines are most likely to have been sized with a tankless unit in mind, though that is something to check on the meter and not assume. Trails at Cottonwood Creek, 5.4 miles from our shop in a straight line, lists homes from 1,731 to 3,765 square feet from First Texas Homes. Lake Shore Village, 3.4 miles away, has Windsor Homes plans from about $409,990. Larger homes mean more bathrooms and more simultaneous demand.
In older streets, such as Dalrock Estates, where listing records show 1983 construction, the gas line is the likelier obstacle. Either way, the answer comes from the fit check, not from the age of the neighborhood.
11Services
All servicesRelated Water Heater Services
07Est. $3,800 - $7,500
Tank-to-Tankless Water Heater Conversion
Gas line and venting changed to suit a wall-hung tankless unit.
12Est. $1,400 - $3,800
New Construction Water Heater Installation
Installs and upgrades for new Rowlett builds, from Lake Park to Sapphire Bay.
13Guides
All guidesGuides That Go Deeper
Tank vs Tankless Water Heater: Which Is Right for Your Rowlett Home?
A plain comparison of tank, tankless and hybrid water heaters for Rowlett homes: cost, space, hot water supply, upkeep and who each one suits.
Read the guideWhat Size Water Heater Do You Need?
How to size a water heater for your household, from 40 to 80 gallon tanks to a tankless unit's flow rate, and why the old tank's size is not a rule.
Read the guideHow to Flush a Water Heater, and Why Hard Water Matters
Flushing a tank water heater once a year clears sediment. Here are the steps, and why moderately hard North Texas water makes it worth doing.
Read the guide14FAQ
Questions People Ask About This
Question not here?
Call and ask. A straight answer and an estimated range on the call, before anybody drives over.
Call (972) 472-8210How much does tankless water heater installation cost in Rowlett?
It is estimated at $3,800 to $7,500, against $1,400 to $2,900 for a like-for-like tank. The gap is mostly the gas line, vent and wall work, not the unit. The written quote splits them.
How much energy does a tankless heater really save?
The U.S. DOE puts it at 24% to 34% more efficient than a storage tank for homes using 41 gallons of hot water a day or less, and 8% to 14% at about 86 gallons a day. The saving is a percentage of your water heating bill.
How long does a tankless water heater last?
The DOE says most last more than 20 years, against 10 to 15 for storage tanks, provided they are flushed for scale. Rowlett's water is moderately hard, so the yearly flush is what protects that life.
Will a tankless heater give me endless hot water?
It gives continuous hot water up to its flow rate. A 5.5 gallon a minute load needs about 178,750 BTU an hour at a 65-degree rise, so running more fixtures than the unit is sized for drops the temperature.
Why does tankless deliver less in winter?
Colder incoming water means a bigger temperature rise. The same 180,000 BTU an hour delivers about 7.2 gallons a minute at a 50-degree rise and about 4.2 at 85 degrees, so we size for January.
Does my gas line need to be upgraded?
Often. A tank burns 30,000 to 40,000 BTU an hour and a whole-house tankless unit asks for 150,000 to 199,900, so the line is checked and sometimes upsized, occasionally back to the meter. It is a named line on the quote.
Does a tankless heater work in a power outage?
No. A gas tankless unit needs power for its fan and controls. A standing-pilot gas tank keeps heating without power, which matters after an event like the February 2021 storm.
What maintenance does tankless need in Rowlett's water?
A descaling flush through the isolation valves about once a year. NTMWD's treated water measured 183 mg/L total hardness in January 2015 (10.7 grains per gallon) and 122 to 160 mg/L in sampled months in 2022 and 2023.
Can I keep the old tank's vent?
Rarely. A tankless unit needs its own vent, plastic for condensing models and stainless for non-condensing. Sometimes the old flue can serve as the chase for the new vent run.
Is tankless worth it for a small household?
It gives the biggest percentage saving, but on a small bill, so the extra $900 to $6,100 is slow to repay. For one or two people a tank is often the better value.
Do tankless heaters need a permit in Rowlett?
Texas cities set their own permit rules, and a gas line and vent change usually brings more scrutiny than a tank swap. We confirm Rowlett's requirement for each job and show any permit as its own line.
Does it save floor space?
Yes. A wall-hung unit frees the 2 to 3 square feet a tank stands on, plus the stand and the drain pan, which matters in a closet or a tight garage bay.
15Sources
Where the Numbers on This Page Come From
Numbers on this page come from the sources below, retrieved October 2026, or from our own estimated price ranges. Where sources disagree or a figure could not be confirmed, the page says so. Distances are straight-line miles.
- U.S. DOE Energy Saver: Tankless or Demand-Type Water Heatersefficiency by daily use, life expectancy
- U.S. EPA WaterSense: showerheads and bathroom faucetsWaterSense flow limits: showerheads 2.0 gpm, bathroom faucets 1.5 gpm
- NWS Fort Worth: DFW normals, means and extremes, 1991-2020temperatures, 100-degree and freeze days
- NTMWD: Protecting Our Drinking Watermoderately hard water, 17.12 conversion
- NTMWD monthly water analysis tables, Wylie treated water, 2015 and 2022-2023total hardness in mg/L; sample months only
- Texas DSHS: February 2021 winter storm mortality report (reported by KSAT)246 deaths statewide
- First Texas Homes: Trails at Cottonwood Creekplan sizes, HOA dues, school district
- Jome: Lake Shore Village by Windsor Homesprice range, school district
- Texas Occupations Code, Chapter 1301 (Plumbing), section 1301.051homestead exemption
- OpenStreetMap geocodes (Nominatim), used to compute straight-line distancesdistances in this site are great-circle miles, so driving distance is longer
- Ray Hubbard Water Heaters: our own estimated price rangesestimates, not quotes; the written quote is the price
16Next step
Book Your Tankless Water Heater Install
For tankless water heater installation in Rowlett, call (972) 472-8210 with the number of bathrooms and people in the house and the age of the current tank. You get an estimated range on the call, the quote in writing after the fit check, and the unit tested at several taps before we leave.