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More Technical FAQ here.


Q1: What type of tankless water heaters do you make?

A1:Noritz manufactures Natural Gas and Propane models only.

Q2: What back-up battery brands does Noritz recommend?


  • APC Smart UPS (750VA or above)
  • Powerware 5115 (500VA or above)
  • Tripp Lite SU1000XL
  • Cyberpower PR1500
  • Belkin F6C100
  • MGE Pulsar EX700RT

Q3: Which recirculation pumps does Noritz recommend?

A3: Recirculation pumps that keeps full warranty:

  • ACT/Metlund® Hot Water D’MAND® S-70T
  • ACT/Metlund® Hot Water D’MAND® S-02T
  • Taco D’MAND pumps 008-DM-PK
  • Taco D’MAND pumps 0011-DM-PK

The above systems must be used in the “on demand” mode; otherwise the terms of the Noritz America Limited Warranty will be reduced to 3 years for replacement of the heat exchanger. Commercial models will keep full commercial warranty even with a recirculation system

Q4: Which anti-freeze brands does Noritz recommend for the NH series boilers?


  • Dowfrost HD by Dow®
  • Cryo-tek AG by Hercules®

Water Heaters and Models

Q5: Can a solar pre-heated water be used with a Noritz unit?

A5: Yes, it is possible to use our products with a solar system. Please have your installer reference the “DOMESTIC HOT WATER WITH SOLAR PRE-HEAT” diagrams for proper installation.

Q6: How do Noritz tankless water heaters work?

A6: Noritz water heaters work on demand – they only heat water when necessary. When a hot water fixture is opened or hot water is required by an appliance, the heater will sense the demand and heat water accordingly. Noritz tankless water heaters continuously heat the water through a heat exchanger. Instead of wasting energy and money re-heating and storing water when it is not needed, tankless water heaters provide only as much hot water as needed.

Q7: What is the difference between a storage tank water heater and a tankless water heater?

A7: Tank water heaters store and heat water at all times, thus incurring higher operating costs, whereas tankless water heaters only heat water as needed. In addition, tank heaters have a limited supply of hot water and will run out of hot water while tankless heaters provide an unlimited supply of hot water – you will never run out. Also, the size of a residential tankless heater is about the size of a carry on suitcase and can be installed virtually anywhere inside or outside. This will allow you to reclaim valuable space in your home.

Q8: How much money can be saved if a Noritz tankless water heater is used in place of a storage tank?

A8: The California Energy Commission estimates that a water heater uses approximately 25% of all energy consumed by any household. Using a Noritz tankless water heater will allow a home to use less energy for water heating and cut water heating costs up to half. The key thing to remember is tankless water heaters only use gas for the hot water you use – that’s the beauty of the technology.

Q9: Which Noritz tankless water heater model is right for my application?

A9: The best way to size a tankless water heater for any application is to estimate the peak flow capacity that will need to be supplied by the water heater at any time. For residential use, this will most likely be the maximum number of showers that may be used simultaneously, multiplied by the flow rate of the showerheads. This calculation should only be done by a qualified plumber or contractor. Once this maximum flow rate is calculated, consult the specifications for each heater to determine which model meets your demand. Please consult with your plumber or contractor, or inquire with Noritz for commercial application sizing.

Q10: How long do tankless water heaters last?

A10: Tankless water heaters can last significantly longer than a traditional tank heater. They are extremely reliable as Noritz units are manufactured with the highest quality parts and put through very rigorous testing and quality control. Also, unlike a tank water heater, all parts are replaceable.

Q11: Will I get instant hot water with a tankless water heater?

A11: No. This is a common misconception of tankless water heaters. A tankless water heater does heat water on-demand instantly, but just like a tank water heater, it will take the same amount of time for the hot water to travel through the plumbing inside your home. If you would like to get instant hot water, there are recirculation pump systems available to hook-up to your tankless water heater. Please ask your installer to see what options you may have in getting instant hot water in your home.
Note: If a recirculation pump is used, we recommend an on-demand system, such as ACT/Metlund® Hot Water D’MAND® and the Taco D’MAND versus a aquastat/timer in order to keep the full warranty coverage.

Q12: Do I need to upgrade my gas line?

A12: Yes. Tankless water heaters do need a larger gas line since its required Btus are higher than tank water heaters. The reason why the Btus are higher is because it needs the energy to heat the water to your set temperature in mere seconds. The actual gas line upgrade size will be depend on which tankless model you choose and the distance from the gas meter. However, the minimum gas line size is 3/4″.

Q13: If a tankless heater requires higher Btus, doesn't this mean it uses more gas?

A13: No. The amount of energy or Btus required to heat water is the same. A simple way of explaining this is when you boil a pot of hot water on your stove. If you were to boil two identical pots of water, but one is on high heat and the other on low heat, the amount of Btus required to boil the water is exactly the same. The only difference is the amount of time it takes for the water to boil. So think of the tankless water heater as the high heat and the tank water heater as the low heat. The energy savings comes in where tankless water heater has a higher energy efficiency and only turns on to heat water when you need it. Whereas a tank water heater is less energy efficient and wastes gas by regularly heating the water in the tank to maintain the set temperature.

Q14: Why do I need electric power for my gas tankless?

A14: Our tankless water heater’s electric power requirement is 120V AC, which is the standard power outlet in U.S. homes. Some local codes have specific requirements on the electric connection. For example, some local codes do not allow extension cords when connecting to the power outlet. Our tankless heaters only come in gas models (natural gas or propane) to heat the water, but electricity is required for the digital remote and to power the PC board, which is the brain of the heater. Also since there is no stand-by pilot light, it uses an electric direct ignition. Electricity consumption is very minimal.

Q15: Can I use my existing venting for my tankless water heater?

A15: No. By code, tankless water heaters must use Category III stainless steel venting. Category III venting is corrosion resistant and gas tight. The venting must be corrosion resistant because a slightly acidic condensate is formed during combustion. This condensation can eat away at your current vent pipe’s galvanized metal and cause major damage to your tankless water heater’s internal components. More importantly, the venting must be gas tight to avoid carbon dioxide leakage. Tankless heaters use a powered exhaust fan to push gas out, as opposed to tank water heaters which use natural draft.
Note: Schedule 40 PVC or CPVC can be used for venting on our condensing technology tankless heaters only.

Q16: Does Noritz offer an electric tankless water heater?

A16: No. Unfortunately we do not offer any electric tankless heater models for homeowners that only have electricity. We only offer natural gas and propane models. Our tankless water heaters are designed for the whole-house, meaning our units can provide enough hot water for an entire home. There are electric tankless water heaters available on the market, but typically a single unit’s output is usually not enough for an entire home and do not qualify for the Energy Star program. Other disadvantages include the large amount of energy consumption that is required to heat the water and it usually takes longer to reach the hot water temperature level at start-up. In areas where there is no gas available, some gas companies do offer gas lines to be installed to your home. We have heard of gas companies in certain areas to offer free gas line installation to homeowners in their service regions.

Q17: Do I need to install a water softener for my tankless unit?

A17: No. It is not required to install a water softener, but if you do live in an area that has very hard water it will eventually harm the performance of your tankless water heater. Some things you can do is to add a water treatment system such as our ScaleShield which prevents scale from forming inside the heater’s copper piping, a whole-house water softener system, or do a routine flush maintenance (frequency depends on your water hardness level).
It is recommended to have your installer test your water hardness or contact your city’s water department for the water test report. Water hardness levels in excess of 12 grains per gallon entering the heater will significantly affect its performance and void your warranty.

Q18: How many tankless heaters do I need for my home?

A18: Our tankless heaters are designed for an entire home. Our smallest unit can provide up to 6.6 gallons per minute and our largest unit can provide up to 13.2 gallons per minute. Some heaters have the Quick-Connect feature which allows identical heaters to be linked to double its output. So how do you figure out how many gallons of hot water you need for your home? Here are some helpful tips:
1. How much hot water do you use at the same time? A standard shower head, dishwasher, washing machine is about 2.5 gallons per minute each. If you typically use all three of these at the same time, that would require 7.5 gallons per minute or the NR98 series. Bath tubs are usually 6-8 gallons per minute, and rain head showers and body sprays definitely requires more hot water than a standard shower head. So if you demand more hot water you will need a larger sized unit or another identical unit with the Quick-Connect feature.
2. Remember to pick the right size unit for realistic situations rather than for your current situation. For example if you have 3 showers in your home, but you only use one shower, you might think the smallest unit is plenty for your situation. The problem is if you have visiting guests over or if ever sell your home, the hot water demand may be different and the heater may be undersized, possibly causing difficulty in selling your home.
3. Here’s the most important tip to understand. Tankless water heater’s gallons per minute output depend on your tap water’s temperature. Simply put, the colder the water the less output you will get from the heater. This is because the colder tap water temperature requires the heater to heat the water more than if it was heating water that is warmer. So we recommend choosing your heater based on your winter season’s tap water temperature. This way you are covering the worst case scenario for your area (consult with your plumber or contractor for final application sizing). Please click here to view the sizing chart and click here for the flow rates.

Q19: Can I install my heater in a manufactured/mobile home?

A19: Yes, our Direct Vent and Outdoor models can be installed in a manufactured/mobile home.

Q20: Where can I purchase a Noritz heater?

A20: Our units are not sold through retailers. They are only available at professional wholesale distributors. Tankless water heaters may require gas line upgrades, stainless steel vent runs as well as local code requirements. Therefore our heaters should only be installed by a licensed professional. Warranty will be void if our units are not installed by a licensed installer.

Q21: Where can I find support documents for older discontinued models?

A21: Please click here.

Controlling the Heater

Q22: Why are there no prices listed for the products?

A22: There are many factors involved in calculating the final cost. These can include installation site, venting requirements, gas line upgrades, and accessories. Federal and local rebates are also available in most areas. To get an estimate from a Noritz PROCard member: Click Here

Q23: At what temperature should the water heater be set?

A23: The set temperature of the water heater depends on how it will be used. A comfortable shower temperature should not be much higher than 105°F (temperatures above 125°F are scalding).

Q24: Do I need a remote controller?

A24: Noritz tankless water heater comes standard with a remote digital temperature controller, which allows you to adjust the water temperature. The controller is optional only on the NR-50, NR-66 & NR-71 models. For other models, the control panel can be wired and installed in a remote location; up to 300 feet away from the unit. The water temperature is displayed on the easy-to-use control panel and can be adjusted using the up and down buttons.
New safety lock-out feature requires the user to follow these steps to go above 120°F:
1. To go above 120°F you must first turn off the power on the remote.
2. Press and hold the flow meter alarm set button until a sound is heard (2 sec.).
3. Change the temperature using the setting buttons to go up to 140°F (WARNING: temperatures above 125°F are scalding!).
4. Set the power button back to on.
Note: If you want to go above 140°F, please contact your installer.