Generator Cooling, need more info.

[Geoff]

I don't hear too many people talking about building a sound box enclosure with soundproofing material. Unless you want a loud rumble from the floor, you are only doing half a job.

[richard5933]

I don't hear too many people talking about building a sound box enclosure with soundproofing material. Unless you want a loud rumble from the floor, you are only doing half a job.

Very true. Our generator bay (and air intake chute) are lines with this: https://www.soundproofcow.com/product/quiet-barrier-specialty-composite-2/

I had to replace a piece recently - not the cheapest but works better than just the standard hood liner material.

The floor above has a layer of lead sheeting covered with a layer of cork, then the carpet pad and carpet. Not sure what the modern equivalent is today, but important to use something to keep the noise down below down below.

[chessie4905]

Installing the diesel generator crossways in the sound insulated bay will greatly reduce outside noise, as most of the noise from a diesel engine comes from the sides. Btw, I would never exhaust genny heat through the roof. Space inside the coach is too precious. Exhaust up the side to roof output, yes when camping around others or if their isn't air movement to carry the fumes away. In some situations, you could use one of those flexible exhaust hoses garages use. If you are camping next to Gary, route the hose over to his coach. He'll never notice.😉

[TomC]

I have a weird setup. I have a high floor transit, like a new look GMC, but made by AMGeneral. I made my gen compartment next to the driver's seat like a front engine. The 10kw Powertech generator sits backwards with the gen head facing forward. I lined the 3/4" plywood box with 1" lead foam insulation. Because of the tight box, my radiator is remote mounted under the driver's seat with a 1/2hp 2spd belt driven single inlet squirrel cage fan from Grainger. I just replaced the first one since the bearings were going (easier to replace then trying to find new bearings). For ventilation through the gen box, I use an 8" inline bathroom ventilator split down to 2-6" hoses pushing air in directly on the alternator head, then exits out the back. The air cleaner is also mounted outside underneath. I now have almost 1800 hours on it, working well with the hottest temp I've been in is 108 (but can only run 2 of the 3 A/C's, not a problem with 2.25" of spray foamed insulation). The exhaust also exits to the left under the driver's seat. I have an 8ft extension I add when sitting to pipe the exhaust up to the roof on the outside. Just another way of doing things. Good Luck, TomC

[chessie4905]

Are those ac's 13,500 or 15k? Do you have any ez starts on any of them?

[sledhead]

I have a 12.5 kw powertech in a hush box up front that is on a air powered roll out .The genny draws air in from the side of the unit and discharges out the bottom of the unit and if I was parked on sand it would blow up a dust storm . So I made a diverter vent to blow the warm air out under the driver side in front of the front wheels . Now it works great even if I am parked on sand . Plus it is quieter on the curb side . As for noise and exhaust that is piped all the way to the back of the coach and there is a chrome tip that sticks out just under the rear bumper . You can just see it to the right of the trailer hitch

So very low noise

   dave

[lostagain]

If having to start the genny in cold weather, some kind of pre heating would be good. Cold air comes in through all the intake and exhaust holes when it is not running, and makes it hard to start. Pre heating the coolant with a diesel boiler would be ideal. Or a hot air duct off the forced air furnace. My propane Honda can be hard to start on a cold morning. But a little persuasion with a shot of ether works good.

JC

[Jim Blackwood]

A water cooled genny would be nice but I'd never find one for the $700 I paid for my air cooled one so that's out for me. On the plus side though it has it's own built in cooling fan. The more I think about it, the more I'm leaning towards having both the inlet and the outlet streetside. Inlet low, outlet high.

One rather trick Idea I've been kicking around though, see what holes you can poke in it. Suppose I were to take about a 1-3/4" holesaw and cut a grid of holes in the floor roughly the size of the genny footprint (a bit less than 3 x 4 ft) then take tubing bends and cut them into 30 or 45 degree segments, insert those into the holes aimed to the rear and tack into the holes flush with the floor. Set the genny over the grid and discharge out the side. The tube segments would act as deflectors to road spray. Might also reduce debris pickup. The suction over that large of an area would not be much so I can't really see dust and leaf pickup being a big issue, especially with the internal baffling of the genset cabinet. I know it's only 6" off the ground but even my shop vac has to get close before it picks things up, and it's not drawing from a 10 sq ft grid. It would be possible to slide in a furnace filter if that were a real concern but I suspect it would be found to be an unnecessary restriction.

The simplicity of just sitting the unit over the intake is  too direct not to be investigated fully. With that scheme it would be feasible to insulate the bay, put a screen on the streetside bay door, and call it done. Even the propane engine exhaust poses little problem and could be exhausted with the cooling discharge. With that much air moving through it'd never be noticed. The propane tank is going in the same bay so venting the bay is going to be required anyway.

Jim

[TomC]

My three Coleman roof tops are 13,500. All have easy start kit. Only once did all three try starting at the same time and just about stalled the generator. Good Luck, TomC

[buswarrior]

Suppose I were to take about a 1-3/4" holesaw and cut a grid of holes in the floor roughly the size of the genny footprint (a bit less than 3 x 4 ft) then take tubing bends and cut them into 30 or 45 degree segments, insert those into the holes aimed to the rear and tack into the holes flush with the floor.

Jim

Do your math on the cross section of your multiple holes. If it doesn't add up to the required intake area, then you are putting the machine at risk.

Air cooled machines need a LOT of air, don't make it gasp for air!

Happy coaching!
Buswarrior

[richard5933]

Would the 30 or 45 degree bends also have to be accounted for in the calculations?

When we installed our high-efficiency furnace there was a chart showing the allowable length for each vent pipe size, and each 45 or 90 bend counted for so many inches of drag. If all your intake is through bends, then you'll have to allow for more flow than otherwise.

[buswarrior]

If straight pieces are used, screwed in on an angle, then it's straight through.

If elbows are used, yes, that's going to slow the air/make resistance/reduce the volume that the machine can gulp in.

Wait until we start messing with a sound proofing switch-back cavity... air has to do 180 degree turn in the cavity, to stop the noises getting out of the enclosure...

Happy coaching!
Buswarrior

[Geoff]

A water cooled genny would be nice but I'd never find one for the $700 I paid for my air cooled one so that's out for me. On the plus side though it has it's own built in cooling fan. The more I think about it, the more I'm leaning towards having both the inlet and the outlet streetside. Inlet low, outlet high.

One rather trick Idea I've been kicking around though, see what holes you can poke in it. Suppose I were to take about a 1-3/4" holesaw and cut a grid of holes in the floor roughly the size of the genny footprint (a bit less than 3 x 4 ft) then take tubing bends and cut them into 30 or 45 degree segments, insert those into the holes aimed to the rear and tack into the holes flush with the floor. Set the genny over the grid and discharge out the side. The tube segments would act as deflectors to road spray. Might also reduce debris pickup. The suction over that large of an area would not be much so I can't really see dust and leaf pickup being a big issue, especially with the internal baffling of the genset cabinet. I know it's only 6" off the ground but even my shop vac has to get close before it picks things up, and it's not drawing from a 10 sq ft grid. It would be possible to slide in a furnace filter if that were a real concern but I suspect it would be found to be an unnecessary restriction.

The simplicity of just sitting the unit over the intake is  too direct not to be investigated fully. With that scheme it would be feasible to insulate the bay, put a screen on the streetside bay door, and call it done. Even the propane engine exhaust poses little problem and could be exhausted with the cooling discharge. With that much air moving through it'd never be noticed. The propane tank is going in the same bay so venting the bay is going to be required anyway.

Jim

Air cooled Diesel generator?  I had one and soon figured out the only way to make it quiet was to put it on a trailer 1/8th of mile away from the bus and run a quiet extension cord.

[sledhead]

A quiet extension cord

I like that

dave

[Gary Hatt - Publisher BCM]

A quiet extension cord

I like that

dave

They are great. They have a lot of insulation on them.