NCC1991 Condensing Commercial Tankless Water Heater

Q. "What does the term "temperature rise" mean?"
A. Temperature rise is the amount the heater raises the temperature of the incoming water, based on the flow rate shown of that water.

Q. "How does a tankless heater provide hot water without a storage tank?"
A. Tankless water heaters heat on demand. The water is heated as it flows through the unit. Automated valves control water and gas flow so that your water comes out at the temperature you set it to.

Q. "What's the difference between a conventional flue and a direct vent?"
A. A conventional flue is what most people are familiar with. It typically consists of a double-wall flue pipe going from the top of the heater through the roof, venting outside. The fixture draws its combustion air from the space around it (utility room, garage, hallway, etc.). A direct-vent unit vents and draws its combustion air through a specially designed pipe from the outside via an adjacent wall.

Q. "What make a condensing tankless water heater different?"
A. Noritz condensing water heaters use a dual heat exchanger system to increase efficiency by using the residual heat from the exhaust temperature, which is captured by the first, corrosion-resistant stainless steel heat exchanger, to preheat incoming water before it runs through the main commercial grade copper heat exchanger. This reduces carbon dioxide emissions and increases efficiency. This also means vented exhaust is lower in temperature than other tankless water heater designs.

Q. "Can I use PVC to vent these tankless water heaters?"
A. The idea of using PVC venting instead of Category III stainless steel venting for condensing tankless water heaters (never recommended by the water heater manufacturer for non-condensing units) is that it will save money on venting since the exhaust temperatures are specified by the manufacturer as within the capabilities of PVC to handle safely. However, we never recommend PVC for venting. In the real world, gas water heaters are rarely maintained to their ideal, which eventually results in raised exhaust temperatures. These raised exhaust temperatures will pass beyond what PVC can safely handle and overheated PVC can release dangerous fumes and even collapse as it fails. For this reason, there is a higher incident of dangerous issues associated with PVC venting on gas tankless water heaters and we cannot, in good conscience, recommend PVC venting for gas water heaters.

Q. "How does the Water Heater Scale Inhibitor System prevent corrosion?"
A. It forms a thin protective layer on the inside of pipes and metal parts. This film or layer is microscopic in thickness and will not build up over time.

Q. "What are the best reasons to install a Scale Inhibitor System?"
A. A Scale Inhibitor System helps protect the system by reducing scale buildup and adding to the longevity and efficiency of the heater.

Q. "What are low NOx emission requirements?"
A. NOx (nitrous oxide) refers to Nitrogen dioxide (NO2) and nitric oxide (NO) combinations (NO + NO2 = NOx) that are emitted in an exhaust system due to the result of the fuel burned to heat water. Many states are adopting low NOx laws that require instantaneous water heaters to meet an emission limit of 14 nanograms of NOx per Joule of heat output.