Will my gas line feed a tankless unit?
That's the first thing we check, and it confirms or kills most conversions. A tank heater sips gas over hours to keep 50 gallons warm. A tankless unit heats water as fast as you can run it, so it wants several times that volume all at once, the moment somebody opens a hot tap.
The half-inch branch that fed your old tank often can’t carry that, and neither can a meter already loaded with a furnace, a range and a dryer. Sizing gas is arithmetic — total demand, pipe diameter, length of run — and the answer is either yes or a larger line. Electric tankless swaps the gas problem for a panel problem: whole-house units draw more than many older Red Oak panels can feed.
Where does a tankless heater vent?
Through its own sealed vent run to an exterior wall or the roof. It can't reuse the B-vent flue your old atmospheric tank drafted up, and it can't share a chimney. That one fact decides where the unit can go more often than closet space does.
Condensing units vent in PVC and route more freely, but they make acidic condensate that has to drain somewhere legal, and a condensate line through an unconditioned attic is its own freeze risk. Non-condensing units need stainless pipe and shorter runs. Exhaust can’t terminate next to a window or a soffit vent.
How often does a tankless unit need descaling here?
Once a year in DFW water. Calcium and magnesium plate the inside of the heat exchanger, the same minerals that bury a tank in sediment, except here they coat the narrow passages the water flows through. Scale cuts flow, makes the burner run longer, and throws error codes that read like a failed unit. We put isolation valves with service ports on every tankless we install, so the yearly descale is a flush under an hour. If yours went in without them, we can add them.
Worth being blunt: a tankless heater in Ellis County that never gets descaled will not outlive the tank it replaced. The longer service life people buy these for is conditional on the maintenance. If nobody's going to think about it once a year, a tank is the more honest choice.
What's true about tankless, and what isn't
Most of what gets said about these units is half right. Here's the other half.
| What you hear |
What's actually true |
| "Endless hot water" |
It won't run out, but it will run thin. The unit heats what passes through it up to a fixed flow rate — two showers and a dishwasher can outrun one sized too small. |
| "Instant hot water" |
On-demand heating, not on-demand delivery. You still wait for hot water to travel the pipe, plus a second for the burner to fire. |
| "It'll cut the gas bill" |
You stop paying to keep 50 gallons hot around the clock. Whether that repays the install depends on the install, so we don't quote a payback period. |
| "Lasts twice as long" |
With annual descaling, yes. Without it in DFW water, no — scale takes the heat exchanger early. |
| "No power needed, it's gas" |
Wrong, and it matters here. Controls, fan, and freeze protection all run on electricity. No power, no hot water. |
What happens to a tankless unit in a hard freeze?
Every tankless unit has built-in freeze protection, and it runs on electricity. February 2021 is the case study nobody here needs explained: the power stayed off, freeze protection stopped on units in garages and on exterior walls, and heat exchangers split. If a deep freeze is coming and the power goes, shut the water off to the unit and drain it. Where we can, we mount the unit somewhere conditioned rather than on a north wall.
Who should actually get one?
Houses where the hot water genuinely runs out: four people showering back to back, a soaker tub that empties a 50-gallon tank on its own. Houses where the tank sits somewhere you’d rather it didn’t, like over a bedroom. And people who’ll stay long enough for the longer service life to matter, and who’ll book the yearly descale.
One bathroom, a dishwasher, and a tank that’s never left you in cold water? A conversion is a lot of gas and venting work for a problem you don’t have, and we’d rather put in the right tank. Call (469) 505-8362 and we’ll check the gas load before you shop for a unit.