Instant or tankless water heater flue??

[Midgetracer31]

I have a new instant water heater it uses a 4 inch round flue. Can anyone direct me to a roof or side mounted vent to use with this? I contemplated running the flue pipe up to the Dometic roof vent and letting it flow out there. Any and all hints or suggestions are certainly welcome.

 

[Gary RV_Wizard]

Can't say that I've ever looked for an RV fitting like that.  Would a clothes dryer type vent fitting work?  Boat engine compartment ventilators should also come in that size and at least some will be a nicer finish (chrome) and more durable than a typical dryer vent.  I've seen them used a dryer vents on RVs with washer/dryers.

I would be surprised if there is room in the fridge vent tower for a 4 inch ppe - most of them are no larger than necessary for the fridge cooling fins.  I had trouble getting an antenna cable through the fridge vent of my current rig.