# Is it advisable to extend the portable generator's exhaust?



## neeraj26jan

Hi guys! I need your advise and help. I have purchased a metal flexi pipe from a local store and attached that with my generator's existing exhaust muffler. I have installed my generator in my empty and abondand store room and also using a exhaust fan for air circulation. The length of the flexi exhaust pipe is about 2 meter (6 feet) and dia is 3 inch. I have attached here some pictures of my current setup, please find them.



















I have noticed that generator heats up very quickly. Is it normal? However i have used only about 30 minutes maximum with this setting continuously.

My question is should i use this echaust extension pipe or should i reduce the length of the pipe from 6 feet to 4 feet or less? Will it cause any negative effect on my generator in long run?

Thanks!


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## exmar

Uh, hopefully you told them what you were using it for. That looks like simple "flex conduit" which isn't airtight and would leak exhaust all along it's length.


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## neeraj26jan

exmar said:


> Uh, hopefully you told them what you were using it for. That looks like simple "flex conduit" which isn't airtight and would leak exhaust all along it's length.


Yes exactly. I had already told them my purpose and they have provided me this pipe. The quality of this pipe is just fine and i don't think it leaks. However most of the length of this pipe is outside from this room.


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## tabora

You really should not run the generator inside a building, especially if there are people in another room. It is quite possible for CO to leak/build up in the area and may lead to death...


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## RedOctobyr

The risks if that pipe _does_ leak is that people may die from carbon monoxide poisoning, which is odorless, and puts you to sleep. So that is not a risk to be taken lightly, and "I don't think it leaks" is something that I would still verify.

One way to check for an exhaust leak would be to use something that smokes. A lit cigarette, an incense stick, etc. With the generator running, hold it next to that pipe, starting at the generator, and then move along the length of the pipe, to the window. If the pipe is leaking, you should see the smoke be blown around.

I would shorten the pipe as much as possible. And I would think a larger diameter pipe would be better. I certainly don't claim to be an expert in modified engine exhausts. But the long pipe creates a restriction in the exhaust, making it harder for the generator to "breathe". If the generator cannot push out all the burned gasses from the previous combustion cycle, some may stay in the cylinder for the next cycle.

The exhaust fan is blowing out, but new air has to come in from somewhere, to replace that exhausted air. Is there another open window in that room? I couldn't quite see where the exhaust pipe goes, but that pipe may get very hot, make sure that it cannot make anything catch on fire.

*Edit: To be clear, even if you cannot locate any leaks, I still think this is a dangerous and bad idea.* I mean no offense, and I'm sure you have reasons for doing it this way. Just as an example, the pipe could be fine for 9 uses. And on the 10th use, the pipe (which is probably not intended to be attached to vibrating machinery) cracks, and now carbon monoxide is accumulating in that room. Even if it doesn't leak when new, that doesn't guarantee it won't leak later.


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## neeraj26jan

RedOctobyr said:


> The risks if that pipe _does_ leak is that people may die from carbon monoxide poisoning, which is odorless, and puts you to sleep. So that is not a risk to be taken lightly, and "I don't think it leaks" is something that I would still verify.
> 
> One way to check for an exhaust leak would be to use something that smokes. A lit cigarette, an incense stick, etc. With the generator running, hold it next to that pipe, starting at the generator, and then move along the length of the pipe, to the window. If the pipe is leaking, you should see the smoke be blown around.
> 
> I would shorten the pipe as much as possible. And I would think a larger diameter pipe would be better. I certainly don't claim to be an expert in modified engine exhausts. But the long pipe creates a restriction in the exhaust, making it harder for the generator to "breathe". If the generator cannot push out all the burned gasses from the previous combustion cycle, some may stay in the cylinder for the next cycle.
> 
> The exhaust fan is blowing out, but new air has to come in from somewhere, to replace that exhausted air. Is there another open window in that room? I couldn't quite see where the exhaust pipe goes, but that pipe may get very hot, make sure that it cannot make anything catch on fire.
> 
> *Edit: To be clear, even if you cannot locate any leaks, I still think this is a dangerous and bad idea.* I mean no offense, and I'm sure you have reasons for doing it this way. Just as an example, the pipe could be fine for 9 uses. And on the 10th use, the pipe (which is probably not intended to be attached to vibrating machinery) cracks, and now carbon monoxide is accumulating in that room. Even if it doesn't leak when new, that doesn't guarantee it won't leak later.


Thank you so much for your advise. That room is almost empty and no one goes and live there. Exhaust pipe is pointing outside of the door where there is a large open area just beside my house, so there is no house, building or any of room outside there.
I will again check the leakage and make some appropriate changes as per your suggestion. Thanks!


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## iowagold

build a generator shack.
concrete block works the best.
steel clad the block to make the block last longer.
acid rain eats the block.

you are better off with the silicone hose style for the exhaust.
at least 3 foot to metal hard pipe.
the generators shake and will break any pipe or weld, bolted connections.
use like a 1.5 inch id black gas pipe for the main exhaust.
or use double wall stainless steel chimney pipe.
you need a lower air inlet for the generator shack.
and run the fan at the top of the generator shack wall
this makes for better cooling.


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## neeraj26jan

iowagold said:


> build a generator shack.
> concrete block works the best.
> steel clad the block to make the block last longer.
> acid rain eats the block.
> 
> you are better off with the silicone hose style for the exhaust.
> at least 3 foot to metal hard pipe.
> the generators shake and will break any pipe or weld, bolted connections.
> use like a 1.5 inch id black gas pipe for the main exhaust.
> or use double wall stainless steel chimney pipe.
> you need a lower air inlet for the generator shack.
> and run the fan at the top of the generator shack wall
> this makes for better cooling.



Thank you for this cool advice! I have reduce the size of the exhaust now from 6' to 2' 5'' only as per suggestion by RedOctobyr in this thread and now i see the significant difference. This is a completely separate and almost empty small room (8' X 8' in size) on a terrace of my house. There is no any door or windows attached with any of other room. Actually i wanted to quite my generator and this really helps and now i want to cool my generator as well. I have installed one exhaust fan also as you can see in the above picture which just throw the hot air outside. Do you think if I install another fan in the opposite side which can take the new fresh air inside the room will also provide much more cooling? I think this will help. Also my question is do you think the silicone hose pipe can bear the heat of the exhaust or will it melt?


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## iowagold

the good red silicone exhaust hose will be ok on the heat.
it is rated for 600 deg F
run an air intake on the room low to the ground.
louver style with screen wire and an furnace air filter to keep the bugs out.
and it holds down the dust a bit as well.
how any cfm is the fan?? and the diameter?

on the larger gen shacks i use 20-21 inch fans that are high speed..
and then run a thermal fan controller as well as a speed control.

let me know if you need links for parts.


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## mark.williams53421

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## speedy2019

I was going todo this because the _exhaust_ from my gen is pointing towards at my outside door about 3 meters away, so was going to get flexipipe to redirect it. But I havent yet, just got a sheet of plywood about 2-3inches away infront of the exhaustut to try to redirct some smoke/fumes away from my door....... Its when I blumming forget to shut my door and start up the gen, because it does smell and smoke a bit with the choke on.


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## Jephthah

The extended exhaust should be bent upwards and outside. The end of the exhaust pipe should be higher than the generator exhaust. Reason? Exhaust gases are hot and generally flow upwards while cool air flows below. But this doesn't mean it has to be too high. Calculations are necessary.


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## Mike M

This looks like a bad idea in-so-many-ways.

I liken this idea to someone going for a long boat ride in a boat that-has-a-known-leak, _oh, but the bilge pump bails the leaking water out so it's ok_......
What if the bilge pump fails?


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## 3Dave

I don't understand why some here are having issue with this. His generator is in a shed, he just didn't call it a generator shed. It's a separate structure from any living quarters. He has an exhaust fan of sort but should have some inlet air flow.

This was originally posted 9 months ago. Perhaps he can return to assure us he and his family are doing well.


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## OrlyP

Old thread. Responding for posterity. 

Definitely make ventilation through and through using a fan with sufficient CFM to promote proper airflow. And even though nobody stays in that "shed", CO detectors can be added to alert anyone who will eventually have to come in and work on the generator (service, refuel, shutdown, etc.). Also have a fire extinguisher always available nearby.

Other optional items:
1. Smoke/Fire detector
2. CCTV for remote monitoring


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