water heating · guide · TN LLP #5045
Tank or Tankless?
What each actually costs, what each is good at, and who should pick which.
Short answer
For most households in this corridor, a good tank heater is the better value. Tankless earns its cost in a house with high or unpredictable hot water demand, a long expected stay, and — importantly here — water treatment to protect it. Without treatment, hard water works against a tankless unit harder than it works against a tank.
Tankless gets sold as the obvious upgrade. It is genuinely better at some things and genuinely worse at others, and which side you land on depends less on the units than on your house and how long you are staying in it.
What tankless is actually good at
It does not run out. For a household that regularly drains a tank — several showers back to back, a large family, a soaking tub — that is a real quality-of-life difference rather than a spec-sheet one.
It takes up far less space, which matters when the heater lives in a closet you would rather use for something else. And it has no standby loss, because it is not keeping forty gallons hot overnight.
What it costs you
The install is a bigger job. Going tankless usually means new gas sizing and new venting, because the unit fires far harder than a tank does when it runs. That is a real cost and it is the part most quotes gloss over.
It is also less forgiving of hard water. A tank tolerates scale for years, gradually. A tankless heat exchanger has narrow passages, and scale in those passages hurts performance quickly. In this area that means a tankless install without treatment is working against itself.
How long you are staying
The efficiency saving is real but it is a slow payback. If you expect to be in the house a long time, that math works. If you might move in a few years, you are largely paying for the convenience rather than recovering the cost.
Side by side
| Factor | Tank | Tankless |
|---|---|---|
| Up-front cost | Lower | Higher, mostly from gas and venting work |
| Runs out of hot water | Yes, then recovers | No |
| Space used | A closet or corner | Wall-mounted, much smaller |
| Standby loss | Keeps water hot around the clock | None |
| Hard water tolerance | Degrades slowly over years | Sensitive — treatment strongly advised here |
| Install complexity | Usually a straight swap | Gas sizing and venting typically change |
| Best for | Most households, predictable demand | High demand, long stay, treated water |
What we would do
If you are replacing a tank, staying put, and nobody is running out of hot water — fit another tank and put the difference toward water treatment. If your household genuinely outruns a tank and you are staying, tankless is worth it, and we would treat the water at the same time rather than after the damage starts.
Permits
Some plumbing work requires a permit and an inspection, and some does not. Whether one is required for your job is determined by the Authority Having Jurisdiction — the city or county building and codes office for your address — and it is at their discretion.
Usually requires a permit
- Water heater replacement and tankless conversion
- Whole-house repiping
- Water service line and sewer line replacement
- Gas line installation and repair
- Relocating a fixture to a new position
Usually does not
- Drain cleaning and clearing blockages
- Emergency and repair work
- Like-for-like fixture replacement
- Water heater repair
- Camera inspection and diagnostics
This is general guidance rather than a ruling, and it can differ from one town to the next. The Authority Having Jurisdiction makes the determination. Across the Bradley–McMinn corridor we pull the permit and book the inspection ourselves. Inside Hamilton County and Chattanooga the permit office does not accept an application from our license class, so permit-required jobs there are referred to a licensed partner who does the work and meets the inspector.
Common questions
Tank or Tankless — questions
Will tankless lower my bills?
Do I really need water treatment with tankless?
Can you convert my existing setup?
Will I know the price before you start?
Are you licensed?
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