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Discussion Starter #1
New member here but I've been lurking for a couple weeks. I live in southwest Florida. After hurricane Irma my wife decided we had to have a generator (I had been saying that for a couple hurricanes but I digress).

I decided on a Champion dual fuel model 100296

I used the L14-30 plug into a inlet box, then into the main breaker panel with an interlock setup.

I built a shed out of a Suncast BMS 4700. See pictures below. When the generator is in use (only twice since the build, for only a couple hours each time) the gas tanks and the shelf they're on are removed. The propane tanks are spread apart exposing the large vent behind them. There is a small double fan unit placed in front of the vent, between the propane tanks. On the other side is a 1320 CFM attic fan. The whole set up is on the side of the house that is in the sun all day long. This was the only location I could put it and have a reasonably short cable length to the inlet box.

My question is, is this set up sufficient to cool the generator for an extended amount of time? I have other questions, and there are other details, but I'll just post this and see what comes back.

Thanks for your time.
Mike

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My first thought was that the gas tanks above the generator was a fire waiting to happen, then you said they are removed during use. Is your fans inlet or exhaust? At that level I think inlet would be best, and would add an exhaust vent up high over the generator, taking advantage of gravity, hot air rises, pushing cooler air across the generator then out the upper level as it is heated. Even if it is one of those combo fans one in/one out I think you would get more heat buildup.
 

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I build 2 operating enclosures from sun cast sheds, they are nice starting points. I like the shelf for gas jugs while the generator isn’t in operation. Personally I’ve kept the intake low and exhaust high but you shouldn’t have any issues As long as the fan is adequate. What’s that fan CFM rating? With the doors closed things heat up very fast and the plastic heat soaks quickly. I used foil faced foam board to create a temperature neutral space and it worked very well.

Where does the exhaust exit? My old champion exited toward the back wall. I ended up building an exhaust system and wrapped it in header wrap. If you don’t build an exhaust, make sure to use adequate heat shielding. The alternator and engines cooling system also exits the back, so heat shielding is very important.
 

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Discussion Starter #4
Thanks for your replies. I'll try to answer them in order.

My first thought was that the gas tanks above the generator was a fire waiting to happen, then you said they are removed during use. Is your fans inlet or exhaust? At that level I think inlet would be best, and would add an exhaust vent up high over the generator, taking advantage of gravity, hot air rises, pushing cooler air across the generator then out the upper level as it is heated. Even if it is one of those combo fans one in/one out I think you would get more heat buildup.
There are 2 fans, one at the vent on the left (not shown), drawing air in, and the attic fan on the right, being the exhaust.
There are also 2 vents in the doors up high (that I don't have a picture of). Hopefully doing what you suggested and venting heat at the highest point in the shed.

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I build 2 operating enclosures from sun cast sheds, they are nice starting points. I like the shelf for gas jugs while the generator isn’t in operation. Personally I’ve kept the intake low and exhaust high but you shouldn’t have any issues As long as the fan is adequate. What’s that fan CFM rating? With the doors closed things heat up very fast and the plastic heat soaks quickly. I used foil faced foam board to create a temperature neutral space and it worked very well.

Where does the exhaust exit? My old champion exited toward the back wall. I ended up building an exhaust system and wrapped it in header wrap. If you don’t build an exhaust, make sure to use adequate heat shielding. The alternator and engines cooling system also exits the back, so heat shielding is very important.
The CFM is 1320 on the attic fan. It might be hard to tell from the pictures but there is cement board across the back of the shed. Like your Champion, mine exhausts out the back. I cut a large square out of the plastic to keep the exhaust heat away from the plastic back wall. Then cut a round hole through the cement board the same size as the exhaust vent that goes over the end of the exhaust pipe. Then used a piece of cement board to cover the square hole and mounted the exhaust vent to that. The idea being that only the cement board touches any part of the exhaust and hopefully keeps all the plastic away from heat.

I also have a remote thermometer that I can place in the shed and read from indoors. But I wouldn't mind suggestions on where in the shed to place it, so as to get a good sense of the situation in the shed.

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I was not familiar with the "shed" you listed. I just looked it up and see it is 70 cu feet in volume. With a 1310 cu foot fan, using as a exhaust you would change the air 18.9 times per minute in an empty shed. Take the volume of your gen and two propane tanks and it might exchange 25 times a minute. At that rate I would think the exhaust fan only with an adequate size intake opening would be enough. Just be sure to shield the exhaust especially where it exits the plastic walls, and also maybe something like a piece of concrete fiberboard between the generator and the plastic walls to help with radiant heat. I wish I could do something like that with mine, but the way the house is made, my meter box is at a front corner by the garage, and no place to put something like that except in the front yard which I prefer not to do.
 

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I used a SunCast BMS2500 shed with a 16" 1,200CFM iLiving ILG8SF16V Exhaust Fan on the right side; the generator is turned so that the exhaust faces the bottom of the fan and exhausts with the airflow. There is a 17" 5NKN4 Dayton gravity operated inlet shutter on the left side. I have a thermal remote monitor mounted top center on rear wall, and a second one mounted outside on the propane tank. The internal alarm is set at 80F and has never gone off in 3 years of operation (about 60 running hours so far).
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Discussion Starter #7
jkingrph, I don't know if you can see my pictures, but they show how I used the cement board on the back wall, and how I accounted for the heat of the exhaust passing through the back wall. Judging by your math I think I should be alright. I was concerned that here in southwest Florida when hurricane season is, is also some of the hottest times of the year. AND the shed is always in direct sun during the day, which is brutal down here.

tabora, I see you live in Cape Elizabeth. I lived there 50+ years ago when my father worked at the Portland Airport, it's a beautiful area. Does your gen get used in the summer, or is it mostly winter running? I remember the winters up there and could see you getting a good bit of use during the winter. I'm concerned because the days can be 95 degrees with a heat index up to 110. In other words I'm starting at 90+ degrees before I even start the generator.

Thanks for the replies,
Mike
 

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Does your gen get used in the summer, or is it mostly winter running?
It's been mostly summer/fall (hurricane/wind storm seasons). The airflow through the box is so great that the temperature inside is lower than outside except during winter. Have not had to use it in winter yet (fingers crossed), just exercising it.
 

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For Florida heat you’ll need a lot of airflow. I recommend a load test, at the generators rated amps before settling. Run it long enough to heat soak everything and monitor the internal temps.
 

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jkingrph, I don't know if you can see my pictures, but they show how I used the cement board on the back wall, and how I accounted for the heat of the exhaust passing through the back wall. Judging by your math I think I should be alright. I was concerned that here in southwest Florida when hurricane season is, is also some of the hottest times of the year. AND the shed is always in direct sun during the day, which is brutal down here.

tabora, I see you live in Cape Elizabeth. I lived there 50+ years ago when my father worked at the Portland Airport, it's a beautiful area. Does your gen get used in the summer, or is it mostly winter running? I remember the winters up there and could see you getting a good bit of use during the winter. I'm concerned because the days can be 95 degrees with a heat index up to 110. In other words I'm starting at 90+ degrees before I even start the generator.

Thanks for the replies,
Mike
start with a metal shed.
then line with cement board.
use lots of powered ventilation.
and external exhaust
click here for the gen shed page.
there is at least one with metal.
 

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Discussion Starter #11
It's been mostly summer/fall (hurricane/wind storm seasons). The airflow through the box is so great that the temperature inside is lower than outside except during winter. Have not had to use it in winter yet (fingers crossed), just exercising it.
Temperature lower than outside... Well that gives me hope. If I can even get close to that I'd be happy. I will try the thermometer where you suggested, up high and in the center.

For Florida heat you’ll need a lot of airflow. I recommend a load test, at the generators rated amps before settling. Run it long enough to heat soak everything and monitor the internal temps.
I run the gen every 6 weeks, for about 20 minutes to a half hour. I'm not due again for a couple weeks but I might move it up to this coming weekend and give your plan a try. I also have an infrared temp gun. I've used it before but it gives different readings all over the place depending on where I was aiming/checking. In the end it left me with more questions than answers because I didn't know which readings to pay attention to. If anyone has any opinions on that I'd be happy to listen.

start with a metal shed.
then line with cement board.
use lots of powered ventilation.
and external exhaust
click here for the gen shed page.
there is at least one with metal.
All good suggestions. But one, I've already spent a good bit of money on the set up I've got. And two, the metal sheds don't hold up very well down here. The humidity turns them to piles of rust pretty quickly. The plastic ones hold up pretty well but again, the sun is rough on everything. I keep a tarp over it all the time to keep the direct sun off. That works well. The shed looks brand new underneath. And you know it's working because the tarps get sun rotted pretty quickly. I've gone through quite a few of them in the year and a half or so that the shed has been built.

Mike
 

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use the good rubber roof coating on the metal!
yea the sun is killer here in the last few years!
bakes any good finish right off.

they make cement board siding...
you might look at that stuff.
and it comes in colors.
just make sure you wear a mask as the material is nasty dusty when you cut it.
 

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The Operation Manual for my portable generator (similar to those shown here) specifies 5' clearance on all sides (including above) during operation.

The Operation Manual for that Champion 9375 generator (linked below) specifies 3' all around clearance and 5' clearance to combustible materials.


My setup permits interior storage and partial protection during operation. After the hurricane passes frequently it is sunny and warm. Plus the generator will tolerate rain, if required.

My generator is stored after the engine running until stalled from the fuel shutoff, then the carburetor bowl manually drained dry. The fuel tank is also manually drained dry. This has been working fine for me for years.
 

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Temperature lower than outside... Well that gives me hope.
Yeah, I thought there was something wrong with the thermal sensor at first... The SunCast BMS2500 is 34 cubic feet empty and is probably about 28CF in use, and the fan replaces that much air close to once a second, so not a lot of thermal buildup.
 

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Yeah, I thought there was something wrong with the thermal sensor at first... The SunCast BMS2500 is 34 cubic feet empty and is probably about 28CF in use, and the fan replaces that much air about once a second, so not a lot of thermal buildup.
So, is it possible that having more cubic space in my shed ( thus more air to remove) is making it harder for my fan to change out the air inside or am I over thinking this again? I don't think I'm going to run out and get a new shed but it would be something to keep in mind when I'm trying to deal with the heat problem.
 

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No need for a New shed. My old champion 7000/9000 ran fine in summer heat in an old sun cast shed with a high velocity 16” exhaust fan and 24x18 intake vent.... with the addition of reflective insulation. Interior temps were well controlled.

Just in case I added a thermal switch in the low oil sensor wire to shut down the generator if temps got out of control. I also monitored temps with a wireless thermometer.
 

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So, is it possible that having more cubic space in my shed ( thus more air to remove) is making it harder for my fan to change out the air inside or am I over thinking this again? I don't think I'm going to run out and get a new shed but it would be something to keep in mind when I'm trying to deal with the heat problem.
I rather doubt that more cubic feet would be detrimental. Ideally you would have an exhaust fan higher than the generator/engine you are wanting to cool and an inlet opening on the opposite side so incoming cooler air would be sucked over/through the generator. Someone said temp inside his box was cooler than outside air and with an engine running in that box I have a hard time understanding how it could possibly be cooler.
 

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Someone said temp inside his box was cooler than outside air and with an engine running in that box I have a hard time understanding how it could possibly be cooler.
Again, because the entire air contents of the shed are being replaced close to once a second with fresh outside air... Wind chill! If I calculated it correctly, the air is moving at about 214.86 linear feet/minute.

I have these remote thermal sensors inside and outside of the shed, with an alarm set to trigger at 80F on the inside sensor. It has never gone off, and often the temperature inside shows lower than the outside.
 

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and there are now blue tooth sensors for temp as well as wifi.
as long as your fans are of good quality and designed for long runs in heat you will be ok.
and variable speed temp controllers for the fans rock!!
 

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Again, because the entire air contents of the shed are being replaced close to once a second with fresh outside air... Wind chill! If I calculated it correctly, the air is moving at about 214.86 linear feet/minute.

I have these remote thermal sensors inside and outside of the shed, with an alarm set to trigger at 80F on the inside sensor. It has never gone off, and often the temperature inside shows lower than the outside.
I do not think wind chill applies to inanimate objects, An inanimate object will cool faster with air moving over it as opposed to still air
 
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