I am hoping that someone with ventilation experience will be able to comment on my proposed ventilation plan. The more I think about the possible solutions the more variables seem to play.
Like John Canfield, I think my exterior electric compartment which houses my Dimension inverter/converter, transfer switch, Surge Guard unit, and Allison ECU runs very hot, especially during the summer. I would like to move the cooler air from the MH interior into the outside electrical compartment to reduce the temperature and maintain a positive pressure to replace the hotter air with cooler air. I am anticipating enough air leakage that there would not be a pressure build up and replacement air would come from house leakage (windows doors vents.)
With John C’s plan in mind
HERE
I went to our 2004 Journey 36G and opened the cover of the interior electrical space located underneath the foot-end of the bed. The 36G design is different then John’s MH. The inside electrical compartment is not located over the outside electrical compartment. But there is already an open electrical wiring trough between the interior and external electrical spaces. The A/C wiring connecting the Dimensions unit and the house circuit breakers mounted in the bed base runs in this trough.
One aside. Apparently when the door of the outside electrical compartment is open and the AC is running then hot air must be drawn from outside through the outside electrical compartment, up the electrical trough, through the inside electrical space, through the vent mounted at the end of the cabinet and into the AC return. I don’t suppose it is a lot of air but I have to think it is like running the AC with a window open. The AC unit has to be working harder and taking longer to reach demand temperature. Even so, the AC unit can freeze us out of there. Hm… another project.
So my question is do I need to install a 3” or 4” duct to move cooler MH air into the exterior electrical space or can I just use the existing electrical trough as an air duct?
To use the existing electrical trough as an air duct I thought of installing an axial 12VDC fan as physically large as possible in front of the existing vent. The fan would push the air to the outside electrical compartment. With the fan continually pushing it seems to me this would cause a positive pressure throughout the entire space (interior electrical, electrical trough, exterior electrical space) preventing air from rising back. However, I was not able to find a 12VDC axial fan large enough to push air to the exterior electrical compartment. The fans that I found were for cabinet cooling. But I did think of the Fan-Tastic Vent product called Endless Breeze. This is a 13” square rotary fan (without legs) x 3” deep with ten 12” blades that provides 900 CFM drawing 3 amps. There are three operating speeds. I spoke with Fan-Tastic Vent and they believe their product would produce the desired results.
Otherwise, I can install an inline blower and blow cooler MH interior air into the outside electrical compartment via a duct. The blower intake would be installed adjacent to the existing interior vent. The duct would be attached to the blower exhaust and installed through the wiring electrical trough down into the outside electrical compartment.
This inline blower plan should accomplish my goal to lower the electrical compartment temperature. However, with the duct installed through one of the odd sized available openings into the outside electrical compartment I do not see how positive pressure can be established. Won’t air be able to circulate back through the various trough opening in to the space above?
If the duct is feasible solution, the 3” duct will be easier to install. I might not be able to snake in the 4” duct. Since this is a 6’ run will the 3” duct do the job? A 4” blower will draw 12 amps; the 3” blower draws 6” amps.
Photo1 shows the exterior of the interior electrical space where I will mount fan and duct (if used). This space is accessed with the bed raised.
Photo2 shows the same space with its cover removed. The back of the A/C electrical box is shown. It is below that box where the largest opening and space is available to install the duct.
Photo3 shows the interior vent that is already installed which I assume is meant to keep this enclosed interior electrical space from overheating.
Photo4 The floor opening shown into the electrical trough space has always been opened and I am assuming it was meant to be that way. With the electrical compartment door opened outside and the MH entrance door opened a nice draft of air can be felt.
Hot air rises and cool air sinks. So with the exterior electrical compartment door closed and the interior space sealed off except for the vent shown in photo 3 is the rising hot air adding heat to this enclosed electrical space located in the bed room or is the cooler air moving down naturally from the MH interior through the vent to help cool off both the interior and exterior electrical compartment? I think it’s heating it up because of the heat load provided by the running engine.
Note you can see the exterior in the upper right corner of the floor opening.
Photo 5 the electrical cable stored in the electrical compartment can be seen.
Photo 6 is taken from the outside looking in and illustrates proximity.
Photo 7 shows the opening where I intend to install the duct (if used) behind the AC electrical box.
Photo 8 shows the snake that I will use to pull the duct (if used) and electrical wiring to run blower or fan and proximity.
I think I prefer the Endless Breeze fan type solution.