Maximum horizontal length for tankless heater

[bzncrew]

I have a Naviem tankless water heater vented horizontally about 16' from the heater to the outside. It vents right into my patio seating area and the gas smell is annoying when it's running.
I'm considering having it rerouted to another wall of the house.

What is the maximum horizontal distance a hot water exhaust vent can travel? I'm thinking it will be about 22' to the other exterior wall.

I'd like to know if this is doable before calling a plumber.

 

[Twowaxhack]

2” pipe can run 60’

max number of elbows -6
Each 90 turn counts as 8 linear ft
Each 45 tun counts as 4 linear ft

Pitch pipe 1/4” per ft or more up from heater to termination.

 

[bzncrew]

Thanks!

That's exactly what I needed.