Tankless vs tank: which is better for my house?
Tankless is the better fit if you'll stay in the house for years and the gas line or electrical service can feed one. A tank costs less to put in and is simpler to live with.
| Tankless | Tank | |
|---|---|---|
| Hot water | Never runs out; typical units deliver 2 to 5 gallons a minute | Plenty at once, then a wait while it reheats |
| Typical life | More than 20 years | 10 to 15 years |
| Up-front cost | Higher, plus any gas, vent or electrical work | Lower |
| Space | Hangs on a wall | Needs floor space in a closet, garage or attic |
| Upkeep | Descaling at least once a year | Flushing about once a year |
| When the power goes out | No hot water | Standing-pilot gas and propane tanks keep working |
The life and flow figures come from the Department of Energy. It also estimates a tankless unit can be 24 to 34 percent more energy efficient than a tank in a home that uses 41 gallons of hot water a day or less, and 8 to 14 percent more in a home that uses around 86 gallons.
What your house needs for a tankless heater
Most of the cost of going tankless is in what feeds the unit, so we look at that first.
- A whole-house gas or propane unit has a burner several times bigger than a gas tank's, so the gas line often needs upsizing. See gas and propane lines.
- Every tankless unit needs its own vent. The old tank's flue usually can't be reused.
- A whole-house electric unit can draw more than 100 amps on several large breakers, which many older homes can't spare. New circuits are a licensed electrician's work, and we'll tell you what the unit calls for before you commit.
- Isolation valves let us descale the unit without cutting pipe, and condensing units need a drain.
How we install a tankless water heater
Size it for January
Water comes in colder in winter, so the unit delivers fewer gallons a minute. We size for January and for how many showers and appliances run at once.
Check what feeds it
We look at the gas line and meter or the propane setup, or the electrical service, plus the vent route.
Mount and connect it
The unit goes on the wall with isolation valves, venting installed to the manufacturer's instructions and a relief valve piped to a safe spot. We install brands local supply houses stock, so parts are easy to get.
Test it with you
We leak-test the gas connections, check the temperature at the taps and show you the service valves.
How often does a tankless water heater need to be flushed?
At least once a year, and more often if your water is hard, the temperature is set high or the house uses a lot of hot water. With tankless, flushing means descaling.
Scale coats the inside of the heat exchanger. Flow drops, the temperature swings, error codes show up, and eventually the heat exchanger can fail. To descale, we close the service valves, pump a descaler through the unit for about an hour, flush it and clean the inlet screen.
Water varies a lot around here. Bonham's lake water ranged from soft to very hard in the city's 2025 water report, while most other towns and rural water systems in the county pump soft well water. If yours tests hard, a water softener ahead of the heater cuts down on scale.
Signs your tankless heater needs service
We repair and service tankless units already in place. Call if you notice:
- An error code on the display
- Water that swings hot and cold in the middle of a shower
- Weaker flow at the hot taps than there used to be
- A unit that won't fire at all
- Water dripping from the unit or its relief valve
Many trace back to scale, so the fix is often a descaling and a clean inlet screen. Others point to a sensor, igniter or fan.
Questions we hear about tankless water heaters
Does an electric tankless water heater work for a whole house?
It can, if the electrical service can carry it and your hot water use is moderate. In winter it also has to heat colder incoming water, which cuts the flow. Many homes do better with electric tankless at a single bath or sink.
Why does my tankless heater run hot and cold?
A short burst of cold between back-to-back uses is normal for most tankless units; plumbers call it a cold water sandwich. Longer swings usually mean scale, a flow too low to keep the burner lit, or a gas supply that can't keep up.
How much does a tankless water heater cost?
More than a tank, because the price covers the unit plus whatever the house needs to feed it: a larger gas line, new venting or new circuits. We give you a written price for the whole job before any work starts.
Can you work on a tankless heater someone else installed?
Yes. We repair and descale most major brands, including units we didn't install. Have the brand and model number handy when you request service; both are on the unit's label.
Replacing a tank that just failed?
If the tank just quit, another tank is usually the faster fix, since going tankless can mean gas line, venting or electrical work first. See water heater repair and replacement. We serve Bonham and the rest of Fannin County.
