RockWood 2618 Ultra V Heater
I have a 2017 2618 Ultra V that had a furnace problem that took months to get fixed because of Forest River's warranty program. When I took possession of my new trailer last year out first campout was Memorial Day on the Thompson River in Montana. It gets cool there at night and I thought the trailer took too long to warm up which is important when you are dry camping. I fought with FR and the dealer for a year before we finally reached a resolution which was to replace the air plenum below the furnace. The shape of the plenum was causing heat to be reflected back to the furnace and causing the overtemp switch to trip. The furnace would come on and the burner would be on for around 2.5 minutes and be off for 1.5 minutes while the furnace fan ran constantly using up my batteries. FR kept saying there was nothing wrong with the design and refused to warranty a fix. Suburban was very supportive and supplied another furnace for testing purposes and when that didn't fix the problem the dealer brought in a HVAC supplier who built a new plenum from the dealers design and now the furnace works properly. I just want to let other 2618 V owners know that if you don't think your furnace is heating your trailer as fast as you would like it may not be just your imagination. FR doesn't want to deal with this so you will have to do some testing yourself.
This is a sort version of a long story.
Best of Luck, dealing with FR you will need all you can get.