Exhaust on a petrol generator

Hi..........Iam wanting to put a petrol, electric start, low noise generator in a shed with access to run it from the outside and seal it inside (a shed inside a shed), but with a lid on the inside for access, the generator will be housed in a heavy duty cage, as we have a few tea leaves around.

Im looking for advice on the following, is it possible to do? and safe?

1) can the exhaust pipe be extended to take the fumes outside, when inside the workshop/shed via a small fan
2) put a pipe on the air intake from the outside, via a small fan
3) how to keep the any noise level down, when inside the workshop/shed

cheers

Yes to the first two minus the fan idea an engine is just a pump after all and will move the air and exhaust on its own if you don't restrict the flow!
As to number three since you are building a box around it just sound insulate the inside of it!

Quote:

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Originally Posted by rlloyd

Hi..........Iam wanting to put a petrol, electric start, low noise generator in a shed with access to run it from the outside and seal it inside (a shed inside a shed), but with a lid on the inside for access, the generator will be housed in a heavy duty cage, as we have a few tea leaves around.

Im looking for advice on the following, is it possible to do? and safe?

1) can the exhaust pipe be extended to take the fumes outside, when inside the workshop/shed via a small fan
2) put a pipe on the air intake from the outside, via a small fan
3) how to keep the any noise level down, when inside the workshop/shed

cheers

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You do have to allow some air flow to cool the engine. Even water-cooled engines sometimes overheat if they don't have a bit of air blowing over the oil pan, etc. Don't know what you mean by a cage but even the generator requires cooling or it will have a short life at best.

Quote:

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Originally Posted by rlloyd

Hi..........Iam wanting to put a petrol, electric start, low noise generator in a shed with access to run it from the outside and seal it inside (a shed inside a shed), but with a lid on the inside for access, the generator will be housed in a heavy duty cage, as we have a few tea leaves around.

Im looking for advice on the following, is it possible to do? and safe?

1) can the exhaust pipe be extended to take the fumes outside, when inside the workshop/shed via a small fan
2) put a pipe on the air intake from the outside, via a small fan
3) how to keep the any noise level down, when inside the workshop/shed

cheers

---

I would recommend that you put your small shed with the generator in it outside your big shed for safety concerns. A small exhaust leak in a small enclosed area like a shed can be deadly. But to answer your question, no fans needed. make sure the exhaust is piped with rigged threaded pipe and use sealant on the threads and run the pipe at least one foot past the outside of the shed. make sure the intake pipe is at least twice as large as your intake at the motor and you must have an air filter. Your biggest problem is going to be the heat from the generator itself. Small air cooled motors will overheat quickly in an enclosed environment.

Ditto for myavid76 but I would bury an old drum with at least 27 times the volume of one cylinder a few feet underground sitting on a few inches of gravel. Put a drain in the bottom, feed in exhaust from top with the exit about 1/2 way down inside drum and take an outlet pipe from the side about 1/4 down,(plastic O.K. for pipes & drum once 3' or more from exhaust port),out under ground at least 6 feet and up and out. Make sure you have a U-bend on the outlet to stop rain water and screen it to stop rodents and wasps.
You can do the same for the intake and with decent sound insulation you will not know it is running.
I've done two like this for remote camp sites where you can hear a Mossie at 2 miles and it works well. Generators are in concrete block enclosures with sand filling and lids made of 1/2 height blocks sand filled between 3/4" treated plywood with pipe from intake drum to enclosure and then just out about 10' with el cheapo ventalation fans powered directly from generator,(when genset is running so are the fans).

I have a generator exhausting through a pipe about 50% larger than the original exhaust stub and about 12 ft. long - no problem. Intake as above is fine, just remember that an intake generates a bit of noise as well. The big problem is static heat build-up around the engine if in a relatively sealed room. Good ventilation is essential or you could have the whole lot catching alight on you (generators generate more than electricity, they generate a considerable amount of heat too, especially under load).

There is one thing to avoid when passing your exhaust pipe through the wall. DO NOT hard fill between the pipe and the wall. If you do it will transmit noise and vibration to the wall.
When we moved into our house 30 years ago we were off grid and the previous owner had installed a nice Lyster diesel gen-set in the garage below. He cemented the exhaust pipe into the wall. When it was running the furniture upstairs would walk around the room. One of my first jobs was to chisel some clearance around the pipe, furniture remained stationary then. Incidentally my second job was to build a generator house about 20 metres from the house, then we didn't even know when it was running, except that we had power.

The area under the house where the generator was originally is now my workshop, when installing that I put my heavy vice on a steel post set in a deep block of concrete whilst pouring the concrete floor. At the top I fixed a triangulated bracket bolted through a concrete block wall, and did likewise for a grinder stand. Her indoors knows when I am grinding or hacksawing something in the vice. The vibration is carried right up into the house. It is the most solidly mounted vice that I have had though.

Quote:

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Originally Posted by Al8236

Yes to the first two minus the fan idea an engine is just a pump after all and will move the air and exhaust on its own if you don't restrict the flow!
As to number three since you are building a box around it just sound insulate the inside of it!

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Thanks for the reply

The box will be 18mm 3x2 18mm with insulation between

PS I'll go into more detail when answering the other replies

Quote:

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Originally Posted by mrehmus2

You do have to allow some air flow to cool the engine. Even water-cooled engines sometimes overheat if they don't have a bit of air blowing over the oil pan, etc. Don't know what you mean by a cage but even the generator requires cooling or it will have a short life at best.

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Thanks for the reply

The generator will sit inside a heavy duty metal cage. with around 3-4" away from the internal walls of the box which will suround it, access to start the generator will be from outside the shed via a side door, which will left open when its running anyway.

The fuel tank will be accessable from the inside & the pull start if needed via a hinged lid, and also to remove the generator if need be.

PS I'll go into more detail when answering the other replies

Quote:

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Originally Posted by myavid76

I would recommend that you put your small shed with the generator in it outside your big shed for safety concerns. A small exhaust leak in a small enclosed area like a shed can be deadly. But to answer your question, no fans needed. make sure the exhaust is piped with rigged threaded pipe and use sealant on the threads and run the pipe at least one foot past the outside of the shed. make sure the intake pipe is at least twice as large as your intake at the motor and you must have an air filter. Your biggest problem is going to be the heat from the generator itself. Small air cooled motors will overheat quickly in an enclosed environment.

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Thanks for the reply

I would put it outside in its own shed, but it will not last two minutes, it has happened not long ago someone thought they had took all the precautions he could, but it still got nicked.

Thanks for the pipe info. was thinking on the same lines.

Hopefully answered you question regarding overheating in the last reply, I could put some 12volt fan to help with air circulation inside the box

PS I'll go into more detail when answering the other replies

cheers

Quote:

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Originally Posted by NortonDommi

Ditto for myavid76 but I would bury an old drum with at least 27 times the volume of one cylinder a few feet underground sitting on a few inches of gravel. Put a drain in the bottom, feed in exhaust from top with the exit about 1/2 way down inside drum and take an outlet pipe from the side about 1/4 down,(plastic O.K. for pipes & drum once 3' or more from exhaust port),out under ground at least 6 feet and up and out. Make sure you have a U-bend on the outlet to stop rain water and screen it to stop rodents and wasps.
You can do the same for the intake and with decent sound insulation you will not know it is running.
I've done two like this for remote camp sites where you can hear a Mossie at 2 miles and it works well. Generators are in concrete block enclosures with sand filling and lids made of 1/2 height blocks sand filled between 3/4" treated plywood with pipe from intake drum to enclosure and then just out about 10' with el cheapo ventalation fans powered directly from generator,(when genset is running so are the fans).

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Thanks for the reply

Would internal fans help if inside the box, only running when the gen is on, the access door from the outside will be open anyway when its running.

PS I'll go into more detail when answering the other replies

cheers

Quote:

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Originally Posted by Hans Pearson

I have a generator exhausting through a pipe about 50% larger than the original exhaust stub and about 12 ft. long - no problem. Intake as above is fine, just remember that an intake generates a bit of noise as well. The big problem is static heat build-up around the engine if in a relatively sealed room. Good ventilation is essential or you could have the whole lot catching alight on you (generators generate more than electricity, they generate a considerable amount of heat too, especially under load).

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Thanks for the reply

Thanks for the pipe info.

The box will be much larger than the generator, and it will have an outside opening which will be open when its running anyway.

PS I'll go into more detail when answering the other replies

cheers

Quote:

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Originally Posted by tonyfoale

There is one thing to avoid when passing your exhaust pipe through the wall. DO NOT hard fill between the pipe and the wall. If you do it will transmit noise and vibration to the wall.
When we moved into our house 30 years ago we were off grid and the previous owner had installed a nice Lyster diesel gen-set in the garage below. He cemented the exhaust pipe into the wall. When it was running the furniture upstairs would walk around the room. One of my first jobs was to chisel some clearance around the pipe, furniture remained stationary then. Incidentally my second job was to build a generator house about 20 metres from the house, then we didn't even know when it was running, except that we had power.

The area under the house where the generator was originally is now my workshop, when installing that I put my heavy vice on a steel post set in a deep block of concrete whilst pouring the concrete floor. At the top I fixed a triangulated bracket bolted through a concrete block wall, and did likewise for a grinder stand. Her indoors knows when I am grinding or hacksawing something in the vice. The vibration is carried right up into the house. It is the most solidly mounted vice that I have had though.

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Thanks for the reply

Thanks for that tip, Would spray foam work when sealing around the pipes that go through the timber wall?

The shed will be made out of- "outside walls" shiplap timber, rendering mesh, 3x2 studs, insulation, rendering mesh and a 18mm board finish, with a 4" wide metal strapping (top to bottom) to keep the timber in place over the shiplap, & hopefully the thiefs getting in (I have tried this method on the other sheds and so far has worked and on one occasion it has made it extremely hard work for them to get break in, with little damage to the shed, except to there chainsaw they used and it clogged the chain up when it hit the redering mesh, I did get a chainsaw for my trouble tho)

I was thinking about the vibration on the wooden floor, would putting some or more heavy duty rubber dampeners work on the underside of the gen. frame as well as the dampeners already on the gen. ?

PS I'll go into more detail when answering the other replies

cheers

I did come across some info regarding sound dampening on youtube, If I raise the box lid at an angle inside the shed it will help reduce the sound waves boucing of the walls.

Has anybody heard anything about it or tried this method.

cheers

Also regarding the access door to the gen. from the outside to start it.

The heavy gauge metal cage I have got will have some holes cut out to access the plug sockets etc. but enough cage to stop it from being pulled out through the wall, it will also be secured to the footings. Also the hole for the door will have an angle iron surround around the door opening and a metal shutter built inside the wall, to block the hole up when not in use, just incase.

cheers