Navien Tankless Water Heaters: An Installer's Honest Review
We install Navien as our go-to tankless water heater. We've been putting them in Philadelphia homes and businesses for years, and we service the ones we've installed plus units installed by other companies. Here's our honest assessment.
What We Like About Navien
Efficiency That Actually Delivers
The NPE-2 series hits .97 UEF (Uniform Energy Factor). That's about as efficient as a water heater gets. In practical terms, this means roughly 15–20% less gas usage compared to a standard tank water heater. On Philadelphia PECO gas rates, that translates to $15–$25/month in savings.
ComfortFlow Recirculation
Navien's built-in recirculation system is the standout feature. It keeps a small buffer of hot water ready so you don't get the "cold water sandwich" (a burst of cold water between the tank residual and the tankless heating). Other brands require a separate recirc pump — Navien builds it in.
Compact Size
Wall-mounted, about the size of a small suitcase. In Philadelphia rowhomes where every square foot matters, this is a real advantage over a 50-gallon tank taking up floor space.
Cascading for Commercial
For larger buildings — restaurants, multi-family, commercial — Navien units can be linked together (cascaded) to scale capacity. We've done setups with 2-3 units serving a small apartment building. Each unit handles its share of the load, and if one goes down, the others keep producing hot water.
Good Tech Support
When we call Navien's tech line, we actually get help. This might sound like a low bar, but in the HVAC industry, some manufacturers' support lines are useless. Navien's technicians know the product and can walk through diagnostics.
What We Don't Love
Annual Maintenance Is Non-Negotiable
Navien tankless units need an annual vinegar flush to remove scale buildup. Philadelphia's water is moderately hard (around 7-10 grains). Skip the flush and you'll lose efficiency, then start getting error codes, then face an expensive repair.
Includes full descaling, filter cleaning, burner inspection, and system test. Budget $400/year for maintenance.
Complexity
A tank water heater has a gas valve, a thermocouple, and a tank. A Navien has a circuit board, flow sensor, inlet filter, burner assembly, heat exchanger, condensate trap, recirc pump, and more. More components = more things that can eventually fail.
That said, most Navien repairs are straightforward if you know the unit. Common issues we see:
- E003 (ignition failure): Usually a dirty flame rod or gas supply issue. $160–$300 repair.
- E012 (flame loss): Gas pressure, venting, or combustion issue. $200–$400 depending on cause.
- E030 (exhaust overheat): Scale buildup reducing heat exchanger efficiency. Flush usually resolves it.
Gas Line Requirements
The NPE-240A draws 199,000 BTU. Many older Philadelphia homes have ¾" gas lines that can't deliver enough volume. Upsizing the gas line to 1" adds $500–$1,500+ to the installation depending on the run length. This is the hidden cost that surprises people.
Navien vs Rinnai vs Noritz
The three most common tankless brands in our market:
- Navien: Best efficiency, built-in recirc, best value. Our pick.
- Rinnai: Proven reliability, slightly lower efficiency, no built-in recirc on most models. A solid alternative — we respect the product.
- Noritz: Good units, less common in our area meaning parts take longer to source. We'll service them but don't install them.
Want a Navien Installed?
Send a photo of your current water heater and we'll assess if your home is tankless-ready.
📷 Get a Quote →Who Should Get a Navien?
- Homes with high hot water demand and adequate gas supply
- Spaces where floor space matters (small utility rooms, closets)
- Homeowners planning to stay long-term (ROI takes 5-8 years)
- Commercial applications needing scalable hot water
Who Shouldn't Get a Navien?
- Emergency replacements where speed matters (we stock Bradford White tanks for same-day)
- Homes with inadequate gas supply and no budget to upgrade
- Homeowners who won't commit to annual maintenance ($400/year)
- Low-demand households (1-2 people) where a tank handles everything fine
Bottom Line
Navien makes the best tankless water heater for the money in our market. The built-in recirc, high efficiency, and good support justify the price. But tankless isn't for everyone — and we'll tell you that upfront. See our tank vs tankless comparison for the honest breakdown.