What Is a Tankless Water Heater? | Deep Dive Plumbing Maryland
Water Heaters
What Is a Tankless Water Heater?
A tankless water heater heats water on demand as it flows through the unit — there is no storage tank. When you turn on a hot tap, cold water passes through a gas burner or electric element and is heated instantly. You never run out of hot water as long as demand doesn't exceed the unit's flow rate.
Tank vs. Tankless — Side by Side
| Feature | Tank Heater | Tankless |
|---|---|---|
| Hot water supply | Limited by tank size | Endless on demand |
| Energy efficiency | Baseline | 20–30% more efficient |
| Lifespan | 8–12 years | 15–20+ years |
| Upfront cost (installed) | Lower upfront cost | Higher upfront cost |
| Space required | Large tank footprint | Wall-mounted, compact |
| Standby heat loss | Yes — heats water 24/7 | None — heats on demand |
| Well water compatibility | Standard | May need pre-filtration |
Who Benefits Most from Tankless
Households that frequently run out of hot water
Homes replacing an aging tank heater (upgrade at replacement time)
Properties with limited space (no room for a large tank)
Homeowners focused on long-term energy savings
Vacation homes or seasonal properties (no standby heat loss)
A Note for Well Water Homes
Tankless units are more sensitive to sediment and mineral buildup than tank heaters. If you have hard water or iron in your well, a whole-house filter or water softener upstream of the unit is strongly recommended — it protects the heat exchanger and maintains efficiency. We assess your water quality as part of every tankless installation.
Have more questions? Browse our full FAQ or contact us directly.