Outside air infiltrating living area

[FrankP]

Hello, I just purchased a 2010 Montana 3455sa and I live in Corpus Christi Texas. We’ve been full timers at an rv park here for the past four years and this is our second rv. I’ve been getting hot air coming in from the kitchen cabinets and around the converter panel which is under the desk on mine. I cut an access panel on the back of a kitchen cabinet next to the converter panel to repair some open neutrals to the converter and when I pulled the piece out I found that there’s a pretty steady flow of outside air in that basement area. I’ve covered the heater returns on the stairs and foamed everything I could get access to but the air coming from that basement area is ridiculous. Is it coming through the heater somehow or where is it coming from. Please help. Electricity bill has doubled since we bought this.

[jsb5717]

Last Summer, when it was 100 degrees or more, I started noticing that very hot air was belching into the coach from the return vents under the stairs…not helpful. I recently opened up the basement wall to take a look. The entire coach is set up to breathe far too easily. There were 2 large holes through the floor into the underbelly, tank area. Through those were plumbing and ducts (to keep that area from freezing in the winter). There were also 2 holes in the wall behind our hutch in the living space into this utility space. There was also space above the basement wall between the floor joists so that the utility space could also breathe into the storage space. All of that allowed for a free flow of air. It was clear that the return vents weren’t really true return vents since the furnace could burn available air from various sources…rendering the furnace even less efficient. I set about to seal every hole…which I did. Rigid foam to insulate and seal the wall behind the hutch…no more holes there. Pieces of rigid foam and spray foam to seal the gaping holes into the underbelly. Rigid foam pieces along the top of the storage wall. Now the only air that the furnace can breathe has to come from the coach so the furnace is a lot more efficient. I’m also hoping that there will be no more belching of hot air into the coach from underneath. Haven’t had hot weather yet so can’t tell yet but it’s got to be an improvement

[FrankP]

Thanks for the advice. We rarely freeze down here so I’ll probably seal up the storage compartment and I’ve got to drop the front plastic bottom to address my tank valve cables so I can foam any openings when I do that. We’re already in the mid 90’s in May so sealing her up takes priority before summer comes.

[jcurtis934]

Some holes just can't be sealed, like the bottom of propane lockers. The front levelers should be big avenues for air as would the hydraulic rams that operate the slides. Since the trailer never moves, it would be more effective to put rigid foam sheets in place to seal off the whole underbelly to the ground all the way around the trailer.