Burying a generator vault into a bank

[Sodo]

I read thru the thread again, Jenkins has taken the time to describe LOTS of good info on sound deadening and ventilation. Instead of rushing out to buy this $25 duct fan (6" & 435cfm) I probably should have bought the Harbor freight unit ($80/ 8" / 1500 cfm) per Curlydave. But he didn't post a pic so the info didn't go into the right memory slot. Thats one of the problems of reading important info on a smartphone. I shoulda looked it up right away. Well anyway thanks Dave, and here's the link for posterity. Harbor Freight 8" 1500cfm ventilator fan $80

For 8,000 watts, (240vAC x 33A) 65 feet I get less than 2% voltage drop for 10ga wire. Seems sufficient because the times I'm truly working the generator full bore will be very seldom and short (couple second peaks?). In any case the wire is ready now, and as Jenkins noted it can be changed easily. Probably not by me though, I'll prob be all stinkbones before a deficiency shows up.

Dragoneggs its already snowing - not sure what to do with that dirt bank, might have to just let it find its own angle of repose (while I ought to do the same ) I can't though, too much other work to get done. Gotta weld today, and I'll be darned if I'm gonna uncoil my 50foot extension cord while theres a BEAUTIFUL buried conduit with everything I need.

 

[jenkinsph]

I thought that was a 10,000 watt genset so yes you can get by with 10 gauge wire but it is maxed out.


The fan I posted was about $80 bucks but has a larger throat for better ventilation and comes with a built in temperature control to let it cycle automatically.

 

[Sodo]

It's 8,000/10,000. My welder uses 7200 at max.

In general, I only need the 8,000w size for the inrush, and then welding is just a minute or two on, then off for awhile It doesn't labor all day at 8,000W. It's mostly just the engine running and needing to cool itself for all the noise it makes.

Well today I did a little testing. I directed to duct towards the "intake" end of the genset, that's all I could do with what I had (time & materials).

With it closed up, (& 435CFM fan running as shown) the temperature quickly rose to beyond the range of the thermometer. The load on the generator is 160watts of lights, a 40A battery charger. So the generators barely working at all, just running it's engine.

I ended up running it like this, with the plywood just to deflect noise. There's snow on the ground, this can't work in the summertime. Gonna need a lot more flow, I'm wondering if 1500CFM isn't enough. Maybe in the summertime it just can't be in the vault. I think I'm going to have to use one of my signal wires for a remote (temperature) alarm.

 

[MossRoad]

Build a temporary wall 3' in front of the door and a couple feet wider so the sound coming out of the open door hits the wall and bounces up. See if that helps. Think an L shaped passageway like in front of a public restroom door.

 

[dragoneggs]

I think you need to vent from the top or near and with a larger diameter fan maybe on a thermostat. I installed a 16in dia. louvered fan in my greenhouse and it really moves the air. It is fairly quiet with louvers. Something like this... Commercial Shutter Fan - Exhaust Fans | Greenhouse Megastore

Probably going to cost you about $200 with a controller/thermostat but you could mount to upper end of door with no ducting and allow for some draw at the bottom. Maybe the intake has a mesh vent to keep the hardy critters out. Forgive me... thinking out loud.

 

[CurlyDave]

...I ended up running it like this, with the plywood just to deflect noise. There's snow on the ground, this can't work in the summertime. Gonna need a lot more flow, I'm wondering if 1500CFM isn't enough. Maybe in the summertime it just can't be in the vault. I think I'm going to have to use one of my signal wires for a remote (temperature) alarm.

In general, an internal combustion engine needs two sources of air, cooling air in and combustion air, and 2 more vents to remove air cooling air out and exhaust. In your situation you need only 3 since cooling air into the vault and combustion air in can be common. As you discovered, just pumping air into a closed chamber is not really going to cool anything since there really isn't any flow.

You need to both run your exhaust outdoors and allow a place for heated cooling air to leave. The air inlet can be constructed from plywood since it only handles ambient air. A square or rectangular cross-section plywood tube 4' long will do the trick here. Set it up with the ends closed and air inlets on the top or sides. Force the air flow to make 2 90 degree bends, which will allow the air to flow, but will attenuate the sound. If you got some of the sound deadening material used to line plenums in hot air heating systems to put inside the duct that would be the cat's meow. I would use galvanized heating duct for cooling air removal, since it is going to be hot. Again 2 90 degree turns, and here you really need the sound control since the duct is metal.

For the exhaust, I used steel exhaust pipe and a tractor muffler, but you could probably get by with gas vent pipe like one would use on a hot water tank. Although, routing the exhaust through a muffler does reduce sound levels.

The HF fan at 1500 cfm was low for my genset, which was larger than yours. You might get by with it, but if I were doing it again I would go larger.

 

[dragoneggs]

I think you need to vent from the top or near and with a larger diameter fan maybe on a thermostat. I installed a 16in dia. louvered fan in my greenhouse and it really moves the air. It is fairly quiet with louvers. Something like this... Commercial Shutter Fan - Exhaust Fans | Greenhouse Megastore

Probably going to cost you about $200 with a controller/thermostat but you could mount to upper end of door with no ducting and allow for some draw at the bottom. Maybe the intake has a mesh vent to keep the hardy critters out. Forgive me... thinking out loud.

Skip the thermostat and have the fan turn on with the gen. :banghead: what was I thinking?

 

[jenkinsph]

I've got both on mine.

A little ramp to go up over the intake duct would be a piece of cake.

Back in post #33 Jim offered an easy solution for moving the genset in and out over the raised floor.

My thought at the time was to mount the genset on a pallet frame of sorts to allow air beneath it. Your tractor could set it in the door easy.


What you lack is cross flow ventilation to eliminate hot pockets. Hot air naturally rises, so allow air in at the bottom and exhaust through the top. You need enough air volume in cfm to eliminate the temperature rise. The turns in the ducting help reduce the noise, but need to be lined with a sound deadening material. The ducting needs to be large enough to handle the job.

I would agree with Curly Dave that a muffler and exhaust would be best if the genset is stationary. About half of the overall heat is exhaust. A large muffler is fairly cheap. Using a muffler and a 1500 cfm fan/exhaust ventilator should fix you up.

 

[jenkinsph]

All this compartment/enclosure discussion also makes me think about ventilation before you start the generator. All boats I know of use bilge blowers to remove fumes before starting the engines. Something you should think about before considering remote start options, you really need to open the door and vent that compartment well.

 

[jenkinsph]

Not to needle you but it is easy to see how complex it can get trying to quiet the genset noise. My Honda inverter gensets operate near 58db or slightly higher, set around a corner of the hill these would be hardly noticed. My Onan diesel genset would be only slightly louder than the Honda. My Miller welder is just LOUD.