Modification to Generator Enclosure

I don't recall where I posted this project before, but this is the photo gallery of my generator enclosure project for our Honda standby gen, and I think every photo has a caption for it that explains things
https://plus.google.com/photos/110979388690716770927/albums/5785954905109999617

This has worked great all winter and spring. But when warmer weather got here the ventilation exhaust temp was a little higher than I liked - around 140° F. The problem is the heat from the muffler. The Honda EM-SX series generators have an extended air baffle from the cylinder that directs the air from the flywheel fan over the cylinder and head, and then the muffler. The hot air is exhausted out the side of the genset thru a grille that covers the muffler.

In colder weather trapping some of that hot air inside the enclosure works nicely to get the temperature in the enclosure up to 70-80° F so the air-cooled engine operates at the correct temp in extreme cold. In warmer weather it traps it too well and the problem is not the ventilation fan capacity - it's the louvered grills that exhaust the air. Too much restriction on the louvered grilles.

So I removed the bottom grille and put a much larger screened opening in the enclosure to exhaust warm air.



Then I put a baffle inside the enclosure made of plywood with the duct stat mounted on it, just above where the hot air is exhausted out the side of the genset. I also installed a 6" diameter duct fan in the top louvered grille. Works much better.



The ventilation fan forces cool air in the top on the opposite end. The combination of the forced ventilation air, plus the plywood baffle, keeps the hot air from the genset from rising up the wall of the enclosure and re-mixing with the cool ventilation forced-air. The airflow is such that it now makes the hot air turn the corner to the end of the enclosure and be exhausted out the screened opening.

As it turns out, the 6" duct fan in the top louvered grille was not even needed. That simple plywood baffle, and making the exhaust vent larger, works so well that the air coming out the top louvered vent is only 3-5° F over ambient temp with the generator at full load for one hour at 87° F ambient temp.

The blast of hot air coming out that screened opening is pretty impressive on a hot day - it killed the grass right by the screen from the heat.

Thankfully, the generator only has to run for peak load support in the summer time, so it doesn't get many hours. It's only burned 1.7 gallons of fuel for the whole month of May so far - and that was because of me doing a bunch of welding and using the Plaz and air compressor in the shop. And we've had an all-time record for energy production for the month of May in the seven years since I've been keeping logs on it - most of it from wind power. We've logged 1,015.2 kWh produced for the last 27 days, or 37.6 kWh/day. So the generator has been mostly resting up for next winter
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Chris