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.
5.0xGas load of a 199,900 BTU/hr unit against a 40,000 BTU/hr tank burner (our arithmetic)Our estimated range
$900 - $6,100Estimated gap between a like-for-like tank and a tankless jobOur estimated range
24% - 34%DOE efficiency gain at 41 gallons a day or lessU.S. DOE
8% - 14%DOE efficiency gain at about 86 gallons a dayU.S. DOE
20+ yearsDOE life expectancy for tanklessU.S. DOE
Short answer
Tank-to-tankless water heater conversion in Rowlett replaces a storage tank with a wall-hung unit, and the gas line, vent, wall and condensate drain usually change with it. A 40,000 BTU an hour tank burner becomes a 199,900 BTU unit, about five times the gas. The job is estimated at $3,800 to $7,500 against $1,400 to $2,900 for a tank.
01The changes
What Is Different About the House After a Conversion
A tank swap changes almost nothing around the heater. A conversion changes five things, and each has its own cost line:
| Item | With a tank | After conversion |
|---|---|---|
| Gas input | About 30,000 to 40,000 BTU/hr | About 150,000 to 199,900 BTU/hr |
| Gas line | Existing, usually small | Often upsized, sometimes from the meter |
| Vent | The tank's flue, sloping up | A dedicated vent: plastic if condensing, stainless if not |
| Drain | A pan, if the tank is above a ceiling | A condensate line, on condensing models |
| Floor and wall | 2 to 3 sq ft of floor and a stand | A wall mount with the maker's clearances |
| Power | None for most gas tanks | An outlet for the fan and controls |
02Gas
The Gas Arithmetic That Decides the Job
Natural gas carries about 1,000 BTU per cubic foot, so a 40,000 BTU an hour tank burner draws roughly 40 cubic feet an hour and a 199,900 BTU unit roughly 200. That is a jump of 5.0 times, from the same meter and often the same pipe. Residential piping is sized from tables in the fuel gas code that depend on the load and the length of the run, and a line that served a tank and a range can be too small for a tankless unit on top.
Three outcomes are common. The line is already big enough, and the conversion is a vent and a wall. The line needs a larger section from where it branches, which costs a modest amount. Or the line needs replacing back to the meter, which is the expensive case and the one that pushes a quote toward $7,500. We check which it is before any quote is written.
03Vent
The Old Flue and the New Vent
A tank's flue is a wide pipe that rises steadily out through the roof, and it is built for hot, buoyant exhaust at low pressure. A tankless unit pushes its exhaust out with a fan, so it needs a vent of the type the maker specifies, run to the length it allows. Condensing models, which extract more heat and so produce cooler exhaust, vent in plastic and make acidic condensate that has to drain. Non-condensing models vent in stainless steel.
Sometimes the old flue can serve as a chase for the new vent, which saves a roof penetration. Often it can't, and the old flue is removed and capped. Either way the vent run is measured against the maker's limits on length and bends before the unit is ordered.
04Water
Flow, Use and What the DOE Says You'll Save
The U.S. Department of Energy puts the efficiency gain of a demand heater at 24% to 34% for homes using 41 gallons or less of hot water a day, and 8% to 14% at about 86 gallons a day, and a life of more than 20 years against 10 to 15 for a tank. The range is wide because the saving is the standing loss of a tank, and a heavy user loses less of it.
That is why the case for conversion rests on more than efficiency. It is the household that runs out of hot water, wants the floor space back, or has a failing tank and a gas line that can be upsized cheaply. The tankless page shows how the sizing works in gallons a minute.
Need Tank-to-Tankless Water Heater Conversion in Rowlett?
Tell us the age of the tank and where the gas meter is and you get an estimated range on the call.
05Cost
What the $3,800 to $7,500 Is Made Of
A like-for-like tank is estimated at $1,400 to $2,900, and a tankless conversion at $3,800 to $7,500. The gap runs from $900 where the line and vent are easy to $6,100 where they aren't. Inside a conversion quote, the items we list are:
- the tankless unit;
- the gas line work, with its length and size;
- the vent, with its material and run;
- the condensate drain, where the model needs one;
- the wall mounting and the electrical outlet;
- isolation valves for flushing the unit later;
- removal of the old tank and its flue, and the permit where Rowlett requires one.
If a quote gives one number for all of it, ask for it split. The cost guide explains the checks.
06Scale
Hard Water and the Valves You Want Fitted Now
The North Texas Municipal Water District calls Rowlett's water moderately hard. Its tables show 183 mg/L total hardness in January 2015, which is 10.7 grains per gallon by NTMWD's divide-by-17.12 rule, and 122 to 160 mg/L in sampled months of 2022 and 2023. A unit without service valves can't easily be descaled, and a coated heat exchanger is the main way a tankless unit loses flow and efficiency. We fit the valves on every conversion for that reason.
07The day
Hour by Hour on a Conversion Day
A conversion usually takes most of a day. The first hour is the fit check and the written quote. Then the water and the gas are shut off, the old tank is drained and the flue is taken down. The next hours go on the gas line and the vent, which is where the time is. The unit is mounted, the water and condensate lines are connected, and the gas joints are leak-tested. The last hour is firing the unit and testing it at several taps with a thermometer, at the highest and lowest flows, so we can show that the temperature holds.
08Rules
Permits and Who Can Do the Work
A change to the gas line and vent brings more scrutiny than a tank swap in most Texas cities, so we confirm Rowlett's requirement for each conversion and pull the permit where one applies. Texas requires work done for customers to be by a plumber licensed through the State Board of Plumbing Examiners. A homeowner may work on their own homestead under Occupations Code 1301.051, but a gas line is not the place to learn.
09Who should say no
Cases Where Conversion Isn't Worth It
It isn't worth it where the gas supply would need a costly upgrade for a small household, where the heater is far from the bathrooms and the wait is the real problem, or where the household uses little hot water and the $900 to $6,100 premium would take most of the unit's life to repay. It is also a weaker choice if outage resilience matters, since a gas tankless unit needs power. In February 2021 Texas counted 246 deaths from Winter Storm Uri, 22 in Dallas County, in outages that lasted days.
10In Rowlett
Conversions Near the Shop
In newer communities such as Lake Shore Village (3.4 miles from our shop in a straight line) and Trails at Cottonwood Creek (5.4), the question is usually an upgrade from a builder's tank, with a gas line that may already be generous. In Dalrock, 3.8 miles away, where a listing shows 1983 construction in Dalrock Estates, the first question is the line. The relocation page covers moving a heater as part of the same job.
11Services
All servicesRelated Water Heater Services
03Est. $3,800 - $7,500
Tankless Water Heater Installation
Wall-hung units sized by flow rate, with the gas line and vent worked out up front.
11Est. $2,200 - $3,800
Water Heater Relocation
Moving a heater from the attic or a tight closet to a spot that is easier to reach.
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 guideHow Much Does Water Heater Installation Cost in Rowlett?
Estimated Rowlett water heater installation costs by type, from a $1,400 tank swap to a $7,500 tankless conversion, and what moves the price.
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 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 a tank-to-tankless conversion 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 runs from about $900 to $6,100 depending on the gas line and vent. The written quote lists each piece.
Will my gas line need to be upgraded?
Often. A tank burner draws about 30,000 to 40,000 BTU an hour and a whole-house tankless unit asks for 150,000 to 199,900, about five times as much gas at the top end. The line is checked and sometimes upsized.
How long does a conversion take?
Most of a day. The gas line and the vent take most of the time, and the unit is tested at several taps at the end.
Can I reuse the tank's flue for the tankless vent?
Sometimes as a chase for the new vent, not as the vent itself. A tankless unit needs the vent type the maker specifies, plastic for condensing models and stainless for non-condensing.
Where does the condensate go?
Condensing units make acidic condensate that drains through a plastic line to a floor drain, a laundry standpipe or a neutralizer. It is planned in during the fit check.
How much will I save on energy?
The DOE says 24% to 34% for a home using 41 gallons a day or less, and 8% to 14% at about 86 gallons a day. That is a percentage of water heating, and it doesn't cancel a $900 to $6,100 premium quickly.
How long does a tankless unit last?
The DOE says more than 20 years, against 10 to 15 for a storage tank, if it is descaled. Rowlett's water measured 183 mg/L in January 2015 and 122 to 160 in sampled months of 2022 and 2023.
Does a tankless heater work in a power cut?
No. It needs power for its fan and controls even on gas. After February 2021 that matters to some households.
Do I need a permit for a conversion?
A gas line and vent change usually needs one in Texas cities, and Rowlett sets its own rules. We confirm and handle it, and any permit is its own line on the quote.
What about hard water?
Rowlett's moderately hard water coats a tankless unit's heat exchanger over time, so we fit service valves so it can be descaled about once a year.
Can I convert from an electric tank to gas tankless?
Only if gas is at the house or can be brought to the heater, which is a larger job. An electric tankless unit is a different choice, with big circuit demands, and we price either.
Is conversion worth it for a small household?
Usually not on cost alone. A one- or two-person household gets the biggest percentage saving, but on a small bill, so the extra price is slow to repay.
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
- 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
- Texas Occupations Code, Chapter 1301 (Plumbing), section 1301.051homestead exemption
- Texas State Board of Plumbing Examinerslicense lookup
- International Code Council: model codes (IRC, IPC, IFGC)model code provisions; local adoption and amendments vary
- Listing record: 8510 Kensington Dr, Dalrock Estates (built 1983)build year 1983, Garland ISD; one listing
- Jome: Lake Shore Village by Windsor Homesprice range, school district
- First Texas Homes: Trails at Cottonwood Creekplan sizes, HOA dues, school district
- 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 Conversion
For tank-to-tankless water heater conversion in Rowlett, call (972) 472-8210 with the age of the tank and where the gas meter and heater are. 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.