At Priceless Plumber, LLC, we believe in honest plumbing. One of the biggest myths in our industry is that a tankless water heater automatically means “instant” hot water.
Tankless systems provide endless hot water, but without the right design, they are not always faster. Here’s the technical breakdown of how we design tankless systems that actually meet homeowner expectations.
1. The “Instant” Misnomer & Ramp-Up Time
If your new tankless unit is installed where your old tank water heater sat, the hot water still has to travel through the same pipes to reach your fixtures.
On top of that, tankless units require a ramp-up period of about 10 seconds to ignite and heat the exchanger. Without a recirculation strategy, homeowners often end up waiting longer for hot water from a more expensive system.
2. Choosing Your Gas Tankless Unit: Best-in-Class Options
Not all tankless systems are created equal. These are the gas units we trust and install:
- Standard Non-Condensing (Exterior): Navien NHW700-180SE NG and Rinnai RE180EN are outdoor workhorses with active freeze protection.
- The Sweet Spot – Rinnai REP160 & REP199: These indoor units are ideal tank replacements. The vent kit often fits directly into the existing opening from a direct-vent tank, avoiding siding repairs.
- The Premium Powerhouse – Navien NPE Series: The NPE-240 delivers up to 11.1 GPM. For most families, the NPE-180A2 at 8.3 GPM allows multiple fixtures to run simultaneously without issue.
3. Electric Tankless: The Stiebel Eltron Standard
If gas is not an option, our top recommendation is the Stiebel Eltron Tempra 24 Plus.
This unit is capable of running a shower and dishwasher at the same time in most Southeast homes. In our experience, its flow control outperforms similarly sized Rheem electric tankless models.
The Power Reality
Electric tankless units are extremely power-hungry. A Rheem RTEX-27 or comparable Stiebel unit requires three 40-amp double-pole breakers and can draw over 110 amps.
We strongly recommend a 300-amp main electrical panel to avoid overloading your home when other major appliances are running.
4. Smart Recirculation: The Key to “Instant” Hot Water
True instant hot water requires recirculation.
- Gas Tankless: Internal pumps can be programmed for peak usage times such as mornings, lunch hours, and evenings.
- Electric Hybrid Loop: Because electric units cannot recirculate directly, we build a custom loop using a small buffer tank. Our preferred setup includes an Ariston 12-gallon tank or a Thermomate 6.5–8 GPM heater, paired with a Watts recirculation pump.
This hybrid approach delivers instant hot water while preserving the endless capacity of a tankless system.
5. Maintenance: The Truth About Descaling
Maintenance frequency depends entirely on water quality:
- Maintenance-Free Zone: Homes with water softeners and sediment filtration may never require descaling.
- Standard Zone: City water typically requires professional descaling every 2–3 years.
- High-Maintenance Zone: Well water without filtration requires annual descaling.
6. Professional Service vs. DIY Maintenance
Professional tankless descaling typically costs $300–$500 due to labor time and monitoring.
DIY homeowners can descale for under $100 using a bucket, submersible pump, washing machine hoses, and white vinegar. With proper research and preparation, this can save hundreds of dollars.
The Priceless Bottom Line
Tankless water heaters can be incredible systems when designed correctly. The key is choosing the right unit, pairing it with a smart recirculation strategy, and matching maintenance expectations to your water quality.
Whether you’re considering a Rinnai REP system or a Stiebel Eltron hybrid loop, Priceless Plumber, LLC ensures your hot water is endless, reliable, and ready when you need it.