Thursday, December 23, 2010

The Navien Tankless Hot Water Heater

We're having a tankless hot water heater installed in our new house. These systems heat the water only when needed, rather than keeping a supply of water heated all the time. We used this sort of system when we lived in Vienna, Austria, and it worked fine for us.

The diagram below shows how the system works.

1 - Exhaust
2 - Heat exchanger
3 - Burner
4 - Fan
5 - Control panel
6 - Flow sensor
7 - Hot water to faucet
8 - Gas supply
9 - Cold water coming in
10 - Cold water to faucet

Plumbing for tankless hot water heater in in storage room downstairs

The Navien tankless system is much smaller than a hot water heater

The large diameter pipes above the unit are intake and exhaust pipes

The intake and exhaust pipes for the Navien exit the house under the deck. A chase has been built to hide these pipes.

The exhaust pipe travels along the back wall of the garage up to the roof 

Bottom of the Navien unit showing water inlets and outlets, as well as circulation inlet, and gas inlet.

Navien energy guide

Navien cover has been removed to permit testing

Closeup of insides of Navien unit

Mother Board -- Error codes show on display (showing 8888)


  1. Thanks for the sharing of such information we will pass it on to our readers.

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  2. Glad you found the info useful. A couple of cautions; (1) Notice the photo of the intake and exhaust pipes. The exhaust pipe has a long, level run. This has caused condensation buildup during cold weather, which shuts down the system (have to reboot it to get ignition), and (2) long runs to some parts of 3500 SF house means longer wait for hot water at the faucet (consider recirc sys).

  3. Got to know a lot about water heater. Such a interesting and informative article. Thanks for sharing with us!

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  4. Really very useful tips are provided here.thank you so much.Keep up the good works.

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