Gen box out of dead Norcold 621

[TobyG]

We are headed out on a two week adventure this summer and we will be camping in campgrounds which is something we don't normally do. We usually boondock. Some CG will not have hookups. So, in preparation I have decided MacGyver my own generator box. Not for noise suppression but, security and convenience. Right now I have to take them in and out of the trailer every time we set up or leave the CG. I have two Honda 2k's and to make the job as simple as possible I have decided to convert my dead Norcold 621 fridge into a gen. box. After removing all the refrigerator "stuff" I'm left with a light weight box with doors.
I plan on wrapping the box with 1/2 plywood, laying it on it's side with the doors vertical to the ground. I have removed the divider between the fridge and freezer so, the gens. will sit side by side. I have 12sq ft of space in the box. I'm trying to figure out how much air flow I will need. If I wanted to replace the air in the box every 3 seconds, by my calculations I would only need a fan that has 240 CFM. Does this sound correct? Also, would this be enough to keep my Honda's within 20 or so degrees of the ambient temp? I had planned on having one 6" vent on the intake side blowing fresh air onto the generators in the box and having 4 5" vents on the opposite side. I have run an exhaust hose from the generator furthest from the 4 5" exhaust vents. The other gen. will butt up to one of the vents right where the exhaust pipe is.
If anyone sees something I may have over looked or might need improving, please let me know. I'm short on free weekends between now and our trip and want to get it right on my 1st attempt.

[SoundGuy]

TobyG wrote:
If I cover the entire back half of the Honda, vent it to the outside and have a 6" porthole on the intake side is there still a need to have a fan to push the cool air into the box?

A properly designed box based on the principles I described does not require the use of an intake fan, just as jauguston's own pics illustrate. I only added a fan to my own interpretation of his box because I was using an existing plastic box rather than a custom designed box and using a fan was easier than trying to cut in intake holes as jauguston did and have the end result look decent. You certainly don't want to cover "the back half" of an EU2000i as that would circumvent the genset's design which uses the case to direct air flow where it's supposed to go. Leave the case as it is and either seal the exhaust bezel as I and jauguston did or invest in a replacement bezel from Generator Line.

[westend]

TobyG wrote:
If I cover the entire back half of the Honda, vent it to the outside and have a 6" porthole on the intake side is there still a need to have a fan to push the cool air into the box?

I would bet there is. The box, itself, creates a back pressure, even with a hole in the intake side. I see most of these generator boxes have one or two intake fans.

[TobyG]

If I cover the entire back half of the Honda, vent it to the outside and have a 6" porthole on the intake side is there still a need to have a fan to push the cool air into the box?

[TobyG]

Glad I asked. Time to rework my plan as there is no way $179 X 2 is happening.

[SoundGuy]

TobyG wrote:
If anyone sees something I may have over looked or might need improving, please let me know.

What you and pretty well everyone else seem to miss is that these inverter style gensets are housed in a plastic case that is purposely designed to keep intake air, heated cooling air, and hot exhaust gases completely separate, meaning that simply sticking one of these gensets into a box and blowing lots of air across it is the wrong approach. What you do want to do is butt the genset exhaust bezel against some sort of contoured seal that closes tightly and prevents hot exhaust gas and hot cooling air from mixing with with cool intake air. My own Honda EU2000i Quiet Box is designed around this principle, as is forum member jauguston's EU1000i quiet box, a design on which mine is based ... his original forum discussion on the topic is here and pics of his box are here. An alternate solution to devising your own method of sealing the exhaust bezel are these commercial exhaust bezels from Generator Line.