Navien NCB-240e Air intake not installed?

[Tegan Easton]

Have a navien Ncb-240e. Installed 2 years ago by professional company. Had multiple issues with install but finally got it working correctly after about a week. Pump went out 18 months later,which they said it shouldn't have but it was covered under warranty, no big deal. In recent research on maintenance, recirculation etc. I came to the realization it appears they have no air intake installed. The exhaust output on the right side runs straight up to a boot in the roof, however, the air intake on the left has no pipe and appears to be capped. Is there a possibility it doesn't need to be a piped through the roof and takes in air from the garage,or is this a major error in installation?
Thank you for your time

 

[Bannerman]

Combustion air may be supplied by the large volume of air from a normally leaky garage. It is preferable however to obtain combustion air from the exterior as a garage will often contain gasoline, paint and other fumes and also vehicle exhaust and dust while sweeping the concrete floor or from cutting wood within.

The air inlet opening cannot be capped (sealed) but must remain open to allow sufficient combustion air to enter.

 

[Sponsor]

 

[Fitter30]

Navien ncb is one of the few heaters that can have only a exhaust. There is a intake air filter inside of cabinet top left that needs to be cleaned and yearly coil cleaning with vinegar.