Installation help

1. Confirm natural gas service

Both models run on natural gas only. If the home uses propane or has no gas, these units are not a fit.

2. Check gas line sizing

A 199,000 BTU heater usually needs more gas than a typical tank heater. An installer should verify the gas line and meter can supply full input alongside your other gas appliances, per the manual and local code.

3. Plan the venting

Tankless heaters use specific vent materials, lengths and terminations. Non-condensing (KNG199INW) and condensing (KNG199ICW) units vent differently, so follow the model's installation manual.

4. Condensate drain (KNG199ICW)

Condensing heaters produce acidic condensate that must be routed to an approved drain, often with a neutralizer where code requires. The non-condensing KNG199INW does not need a condensate drain.

5. Water connections and quality

Check water pressure, shutoff/service valves for flushing, and water hardness. A scale inhibitor, cartridge or filter is not a water softener and does not qualify for the KNG199ICW heat-exchanger flushing exception.

KSCALC replacement cartridge for the Scale Inhibitor System (Store listing: for the Extended Warranty Plan only.)

6. Electrical

The unit needs a standard electrical connection for its controls and fan. Confirm requirements in the manual.

7. Ongoing maintenance

For KNG199ICW heat-exchanger flushing: No flushing is required when a water softener is present and consistently operational. Periodic flushing is required when a softener is absent or is not consistently operational. KNG199ICW heat-exchanger flushing only. Inlet-filter cleaning, exterior care, inspections and other maintenance remain required. A scale inhibitor, cartridge or filter is not a water softener and does not qualify for this exception. Without a consistently operational softener, contact support to establish the hardness-informed flushing interval, including for 0–4 grains/gallon or boundary values. Manufacturer/user clarification received 2026-10-27, for KNG199ICW heat-exchanger flushing. Original manuals unchanged. Follow the INW maintenance instructions separately. Keep the air intake and vent clear.