Tank less Water Heater

Butch50, I have a Nexus 32SC which has an Atwood on-demand water heater. I would guess yours will be the same. An advantage I find is that if I want to work in the RV between trips and need hot water, it is available without turning on the heater and waiting for a tankful of water to reach temperature. One problem I had with mine that you should be mindful of is the little black plastic vent hole you will see on the outside of the heater cover. It is connected to one side of a diaphragm switch that is used to sense vacuum in the combustion exhaust blower, or in other words, to prove the blower is running. If the switch doesn't make, the ignition cycle will not start. I initially had a problem with erratic to no operation of the heater. I finally determined that the pressure switch was the problem and contacted Atwood. They promptly sent me a new switch. When I removed the old switch, the problem was apparent. The port that connected to the outside vent was blocked by what appeared to be mud. I assume a mud dauber decided to take up residence. I cleared the port and glued a small piece of screen over the outside vent and all is well. I was amazed that happened at the factory where the RV was never really outside before I took delivery and the problem started within a couple of days afterwards.