Frequently Asked Questions

A Navien tankless water heater is a wall-mounted, gas-fired unit that heats water on demand rather than storing it in a tank. When you open a hot water faucet, cold water flows through the unit and is heated instantly by a gas burner. Navien is the #1 selling brand of gas tankless water heaters in North America. Their condensing technology captures extra heat from exhaust gases, achieving up to 0.96 Uniform Energy Factor (UEF), making them among the most efficient water heaters available.

Navien tankless water heaters have an expected lifespan of up to 20 years with proper maintenance. This is nearly double the 8 to 12 year average lifespan of a traditional tank water heater. Over that time, you could end up buying one or two replacement tank heaters, while a single Navien unit keeps running.

Condensing models (NPE-A2 and NPE-S2) capture additional heat from exhaust gases before they are vented outside, achieving up to 0.96 UEF efficiency. Because the exhaust is cooled significantly, they can use affordable PVC or polypropylene venting. However, condensing units produce acidic condensate that requires a neutralizer and drain line.

Non-condensing models (NHW-AI for indoor and NHW-AE for outdoor) vent exhaust at higher temperatures and require stainless steel or Category III venting, but do not produce condensate. The NHW-AE outdoor model requires no venting at all. Condensing models generally have lower operating costs due to their higher efficiency.

ComfortFlow is Navien's patented system that includes a built-in recirculation pump, a 0.5-gallon buffer tank, and fine-tuned controls. It solves the "cold-water sandwich" effect, where you get brief bursts of cold water between hot water draws, and ensures hot water delivery even at very low flow rates. ComfortFlow is built into the NPE-A2 condensing series and the NHW-AI and NHW-AE non-condensing series.

We install the full range of Navien residential tankless water heaters:

NPE-A2 Series — Condensing with built-in ComfortFlow recirculation pump and buffer tank. Available in 150,000, 175,000, and 199,000 BTU models with flow rates up to 8.4 GPM.

NPE-S2 Series — Condensing, standard model without built-in recirculation. Same high efficiency (up to 0.96 UEF) at a lower price point.

NHW-AI Series — Non-condensing, indoor installation. Features ComfortFlow and Navien's patented NaviTech stainless steel heat exchanger. Available in 160,000, 180,000, and 199,900 BTU models.

NHW-AE Series — Non-condensing, outdoor installation. No venting required. Same ComfortFlow technology with weather-resistant enclosure.

All models are available in natural gas and liquid propane (LP) configurations.

It depends on the model and the temperature rise needed. The most popular model, the NPE-240A2, delivers up to 5.6 GPM at a 45°F rise (the standard measure) and up to 8.4 GPM at a lower temperature rise. That 5.6 GPM is enough to run two showers and a kitchen faucet simultaneously in most Long Island homes. For larger households, Navien's ReadyLink system allows cascading up to 32 units together using simple cable connections.

Yes. According to the U.S. Department of Energy, tankless water heaters are 24 to 34% more energy-efficient than conventional tank water heaters for homes that use 41 gallons or less of hot water daily. Navien's condensing models have an estimated yearly energy cost of around $197, compared to nearly $300 for a typical tank heater. Combined with the 20-year lifespan (versus 8 to 12 years for a tank), the total cost of ownership is significantly lower over time.

Yes. All Navien tankless water heaters are designed to burn natural gas and can be converted to liquid propane (LP) using a Navien Gas Conversion Kit. The kit must be installed by a qualified technician. We handle LP conversions as part of our installation service.

Installation costs vary based on the model selected, your home's existing gas line and venting setup, and any code upgrades required. Tankless installations on Long Island typically range from $3,000 to $5,500 including the unit. We provide free, no-obligation estimates so you know the exact cost before any work begins. We also offer financing options to help manage the investment.

It depends on the model type:

Condensing models (NPE-A2, NPE-S2): Use affordable 2-inch PVC Schedule 40, CPVC Schedule 80, or approved polypropylene venting. Do not use cellular core PVC (ASTM F891), cellular core CPVC, or Radel (polyphenolsulfone).

Non-condensing indoor (NHW-AI): Requires stainless steel or Category III venting.

Non-condensing outdoor (NHW-AE): No venting required. The unit is installed on an exterior wall.

All Navien models are direct-vent units, meaning they draw combustion air from outside and exhaust to outside. They cannot share venting with other appliances and cannot be vented through an existing chimney.

Possibly. A Navien tankless water heater requires adequate gas flow to support its BTU rating. The gas line must maintain proper pressure: typically 3.5 inches of water column (WC) for natural gas and 11 inches WC for propane. If your existing gas line is undersized (commonly 1/2-inch), it may need to be upgraded to 3/4-inch or larger to deliver sufficient volume. We assess your gas line during the free estimate and include any necessary upgrades in the project scope. Navien recommends avoiding 1/2-inch corrugated connectors, as they can cause operational noise.

Condensing Navien models (NPE-A2 and NPE-S2) extract so much heat from exhaust gases that water vapor condenses into a mildly acidic liquid. A condensate neutralizer is a small inline device containing calcium carbonate media that raises the pH of this condensate before it enters your drain. Local building codes on Long Island typically require a neutralizer for condensing water heaters. We install the neutralizer as part of every condensing model installation, and we offer ongoing condensate neutralizer service to replace the media when it's depleted.

Yes, but the electrical requirements are minimal. Navien tankless water heaters draw only 2 to 4 amps and plug into a standard 120V household outlet with the factory-installed 3-prong grounded plug. No dedicated electrical line is needed. However, this does mean the unit will not operate during a power outage unless you have a backup generator or battery system.

A straightforward replacement of a tank water heater with a Navien tankless unit typically takes 4 to 8 hours, depending on the complexity of your gas line, venting, and plumbing modifications. If we're installing in a new location or significant upgrades are needed, it may take a full day. We'll give you a clear timeline during your estimate appointment.

Navien strongly recommends professional installation by a licensed plumbing contractor. Installation involves gas line connections, venting, condensate drainage, and electrical work, all of which must meet local building codes. Improper installation can void your Navien warranty and create safety hazards. All Island Comfort is fully licensed and insured, and our installations comply with all Long Island building codes.

Here are the error codes we see most frequently on Long Island service calls:

E001 (Ignition Failure): The unit could not ignite. Often caused by a gas supply interruption, a blocked or dirty air filter, or a damaged ignition component.

E002 (Overheating): The unit temperature exceeded safe limits. Usually caused by a clogged heat exchanger due to scale buildup or a faulty temperature sensor.

E010 (Exhaust Blockage): Abnormal exhaust pressure detected. Typically caused by a clogged vent pipe, bird nest or debris in the flue, or incorrect vent installation.

E012 (Flame Loss): The burner ignited but the flame went out. Usually caused by low gas pressure, a dirty burner, or insufficient gas supply.

E016 (Heat Exchanger Issue): Often caused by calcification from hard water, which can lead to overheating, pinhole leaks, or flow sensor problems.

E760 (Descaling Reminder): The unit is signaling that it's time for a maintenance flush.

If your Navien displays an error code, don't ignore it. Call us at (631) 591-2289 for prompt diagnosis and repair.

Before calling for service, check these common causes: make sure the gas supply valve is fully open, verify the unit has power (check the outlet and any GFCI reset buttons), check the EZNav display panel for error codes, and make sure your water flow is above the minimum activation rate. If the unit activates but produces inconsistent hot water, the flow sensor may need attention. Opening and closing the pressure relief valve near the heater's outlet can sometimes reset the flow sensor. If the problem persists, call us for a professional diagnosis.

Short cycling (the unit firing and shutting off repeatedly) is often a sign of a failing control board, fluctuating gas pressure, or an issue with the exhaust venting. It can also happen if the minimum flow rate is barely being met, such as with a single low-flow faucet. If the problem happens consistently, contact us for service. Continuing to operate a short-cycling unit can cause further damage to internal components.

Yes. All Island Comfort provides 24/7 emergency Navien tankless water heater repair service across all of Long Island, including Nassau County and Suffolk County. If your unit stops working or displays an error code, call us at (631) 591-2289 any time, day or night. We stock common Navien replacement parts on our service vehicles to complete most repairs in a single visit.

Repair costs vary depending on the issue and the parts needed. Minor repairs such as sensor replacements or filter cleanings are generally less expensive, while major repairs like control board or heat exchanger replacement cost more. We provide an upfront diagnosis and cost estimate before performing any repair work, so there are no surprises. If your unit is still under Navien's warranty, parts may be covered.

Navien recommends annual descaling (flushing) to remove mineral buildup from the heat exchanger. Long Island water tends to have moderate to high mineral content, so annual flushing is especially important here. If you have particularly hard water, flushing every 6 months is advisable. The process involves circulating white vinegar or a commercial descaling solution through the unit for at least 45 minutes, followed by a fresh water flush for a minimum of 10 minutes. Navien recommends having a professional perform the descaling, as improper technique can damage the unit and potentially void your warranty.

A professional annual maintenance visit for a Navien tankless water heater typically includes descaling/flushing the heat exchanger to remove mineral buildup, cleaning the water inlet filter to prevent flow restriction, inspecting the venting system for blockages or damage, checking the condensate neutralizer media (on condensing models) and replacing if depleted, testing gas pressure and burner operation, checking the ignition system and flame rod, inspecting all water and gas connections for leaks, and reviewing error code history on the EZNav control panel.

Yes, this is one maintenance task most homeowners can handle. The cold water inlet filter is located where the cold water line connects to the unit. Turn off the water supply, place a small bucket underneath, unscrew the filter housing, remove the screen filter, rinse it clean under running water, and reinstall. Cleaning this filter regularly helps prevent reduced water flow and overheating errors. Refer to your Navien owner's manual for model-specific instructions.

The calcium carbonate media inside a condensate neutralizer gradually dissolves as it neutralizes acidic condensate. The replacement frequency depends on how much hot water your household uses, but in most homes, the media lasts 12 to 18 months. We check the neutralizer during annual maintenance and replace the media as needed. We also offer standalone condensate neutralizer service if yours needs attention between annual visits.

Navien's residential warranty for the NPE-2 condensing series includes a 15-year limited warranty on the heat exchanger, a 5-year limited warranty on parts, and a 1-year limited labor warranty. The NHW-A non-condensing series also carries a 15-year heat exchanger warranty backed by their patented NaviTech stainless steel construction. For commercial applications, coverage is reduced to 8 years on the heat exchanger and 5 years on parts. The warranty must be registered within 30 days of installation and applies only at the original installation site. We handle warranty registration as part of every installation.

Yes. We understand that a tankless water heater installation is a significant investment, and we offer flexible financing options to make it more affordable. Ask about our current financing programs when you schedule your free estimate.

Yes! We currently offer a Friends & Family discount of $150 off tankless water heater installation. Visit our Coupons & Specials page for all current offers and seasonal promotions.

All Island Comfort serves all of Long Island, including Nassau County and Suffolk County. From Montauk to the Queens border, we're available for installation, repair, and maintenance of Navien tankless water heaters. Visit our Service Area page for a full list of towns and communities we serve.

Yes. All Island Comfort is fully licensed, bonded, and insured for plumbing and heating work on Long Island. Our technicians are trained specifically on Navien tankless water heater systems and stay current with manufacturer updates, local building codes, and industry best practices.

You can reach us in several ways: call (631) 591-2289 any time (we answer 24/7), fill out the form on our Contact page, or use the Schedule Service button at the top of any page. For installations, we provide free on-site estimates. For repairs, we'll diagnose the issue and provide a cost estimate before beginning any work.