Small diesel gen set for battery charging.

[697-Nodad]

Hi all,

I'm looking to install a small 3phase genset as an on demand battery charger.
(to be installed solar setup and workshop )

Question is - Just how sound proof could I build a shed to house the thing in?

Neighbours are ~ 70 meters away so it would need to be absolutely whisper quiet.

Anyone had experience doing this? - was even thinking of digging a bunker.

Cheers

[Vern]

Start by getting a generator already in an enclosure, then build a room around that and line the inside walls with something to absorb the sound, wool batts or the likes. Don't forget to extend the exhaust and also allow good ventilation to the room.
Last stand alone solar job I did had a diesel genset outside, noisy as hell. We are looking at alternatives at the moment, mainly for noise and much larger fuel tank.

[Homestar]

I do hire gensets for a living and we install them very close to houses on occasion and I also spend 10 years installing permanant machines into buildings - both design, installation and commissioning. - Verns idea is the way to go - buy one already in an acoustic enclosure and install that inside a building - that will be by far the best way to start, and cheaper overall despite the machine being more expensive to buy.

You can get them in a single skinned enclosure down to 62dBa @ 7 metres, but they are a bit rarer - the most common enclosures will be around 70 @ 7 for a small machine.

DON'T put it in a hole - leaking carbon monoxide will build up in it and kill anyone that goes down there. Build an insulated shed around it and bung on a couple of extra mufflers to the system - most engines will be fine with the extra back pressure - the engine manufacturer will be able to provide a spec for the maximum allowable for this.

Hay bales cannot be underestimated in their ability to stop noise - we use them all the time as they are cheap and easy for temporary installations but if you have a tarped layer of hay bales on the outside of the building on the neighbours side, it would do a huge amount - don't put them inside as you'll risk setting them on fire with your genset.

Harder to mask will be the low frequency harmonics it will generate - you will need to isolate these by using some form of isolator under the machine - if you put it straight on The ground or a concrete slab you may run into issues. This can be something as simple as some waffle pod rubber pads or as extravagant as some engineered anti vibration mounts.

Although the EPA can supply you guidelines to what sort of levels you should be shooting for at your property boundary, there is no such thing as an acceptable level - if someone complains about it, it's seen to be too loud by the EPA so bear that in mind. I've tested installations in the middle of the night where the triple enclosure made the generator quieter than the ambient surrounding noise but the neighbours could 'feel' it running so extra anti vibration isolators were required and the EPA was on the customers back - including issuing fines - until it was sorted - and this was only a standby unit that started once in a blue moon.

At 70 meters away though, you should easily be able to make something quiet enough to keep your neighbours happy.

[Homestar]

Oh, and remember you have to get air in and out of the shed/building you put this in and that will be the biggest area that noise can escape from. The outlet needs to be around 120% of your radiator area in size and the inlet needs to be at least 150% of this.

[dromader driver]

in my earlier years I did a couple of larger genset installations with some really good lessons learnt.
- cooling fans on a radiator are very noisy as they rely on high velocity air. my preference now is for cooling tower/ baltimore cooler.
- concrete block wall is good noise baffle. Use high walls well above engine height with ventilation at the top.
- rubber mount the whole thing on an independant slab
- exhaust outlet to the side of the building away from noise sensitive areas.
- skillion roof with the opening on the high side of the skillion to allow ventilation works well. opening away from sensitive part of site.
- solid closed doors for access at ground level.
- use steel styrofoam sandwich for the skilion roof again cuts vibration, resonance and noise.
- mesh all the access points to stop birds getting in.

The best feedback was from my boss when we were discussing the installation standing outside with the doors shut. His question as he had seen the set installed at the original site was how did we get it so quiet.

[Blknight.aus]

If you can do it.....

remote the radiator, put it in a chimney like stack at a 45 degree angle with a low speed fan pushing air up through it from the bottom.

dont mount anything to the structure of the shed, have additional frames made that are smaller than the shed and free standing. mount everything on these

hang heavy canvas or horse blankets inside the shed a couple of inches free from the walls

sections of tyre tread make good vibration insulators and if you make the mounts up for the genny to include a jacking frame so you can use a small bottle jack to lift the genny a couple of inches are easy to replace.