Exhaust Extension for Portable Propane Generator

trane · Joined: 21 Aug 2008 Posts: 6 Location: fl

I have a 3500 watt portable propane generator that I plan to use for temporary power outages in my FL home. I want to use it in a lanai area that during storms when power outages are likely to occur will be temporarily closed-in with aluminum shutters. To operate it safely in this setting, I will need to extend the exhaust to the outside. I plan to penetrate one of the aluminum shutter panels and somehow direct the exhaust to the outside. If anyone has suggestions on a good way to accomplish this Idea

it would be greatly appreciated Wink

aischa · Posted: Thu Aug 21, 2008 1:46 pm Post subject:

The safest thing is to operate the generator outside, as required by law. You are not supposed to use the generator inside.

I have seen people use a regular plumbing PVC hose that fits on the muffler to lead the exhaust gases from the RV generator under the rig to the roof of the RV. I thought that wa a good idea.
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trane · Joined: 21 Aug 2008 Posts: 6 Location: fl

[quote="aischa"]safest thing is to operate the generator outside, as requiered by law. You are not supposed to use the generator inside.

I have seen people use a regular plumbing PVC hose that fits on the muffler to lead the exhaust gases from the RV generator under the rig to the roof of the RV. I thought that wa a good idea[/quote]

Thanks very much for your reply! It's really not an inside space but rather a poolside area that is shuttered with loosely fitted and bolted temporary aluminum protective panels that have many places for air transfer. To get to this poolside area, you have to exit sealed sliders or doors that exit the home. I've worked with PVC piping many times and always thought the heat from the exhaust would melt it. This exhaust extension that I'm trying to fabricate won't be very complicated and just involve a straight flexible piece horizontally from the muffler (which terminates horizontally) less than 2' through one of the aluminum panels. One consideration will have to be the wind (possibly 50-100 miles per hour at times) blowing against this extension as it exits to the outside that could present a significant back pressure situation periodically. I think I will have to install some sort of omnidirectional deflector as it terminates to the outside.

porscheracer · Posted: Thu Aug 21, 2008 6:02 pm Post subject:

If you're worried about the "back pressure" affecting the operation of the generator, don't. If it's an issue with the hose being slapped about, that's a different thing.

The generator extensions for motorhomes have a metal adapter that goes on the exhaust pipe, and there's an air-directed gap between it and the plastic to provide a chimney effect. The plastic never gets that hot - maybe 140 or so.
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trane · Joined: 21 Aug 2008 Posts: 6 Location: fl

[quote="porscheracer"]If you're worried about the "back pressure" affecting the operation of the generator, don't. If it's an issue with the hose being slapped about, that's a different thing.

The generator extensions for motorhomes have a metal adapter that goes on the exhaust pipe, and there's an air-directed gap between it and the plastic to provide a chimney effect. The plastic never gets that hot - maybe 140 or so.[/quote]

That explains the heat exposure of the PVC. Thanks! As far as the hose being slapped around, shouldn't be a big deal; in fact that might help make it somewhat omnidirectional! It's good to know that the back pressure is nothing to worry about! Do you know where I can obtain a extension kit, RV supply, etc.?

SamnGlenAllenVa · Joined: 13 Mar 2008 Posts: 154 Location: its in my name

Geez man...even if it is what you say, it sounds like your lanai/pool room/whatever is CONNECTED to the house as in under one roof?

How long is this run?

And there have been several deaths at NASCAR races from CO blown from adjacent units!

RIR requires all RVs to use a Genturi...but if it is blowing right into the intake of your neighbor...what's the difference?

You really need to thing about this more...and oooh how about making me your beneficiary on the life insurance?

CO posioning is no fun...I had a kid almost kill 20 or so scouts and 2 adults when he got up cold in the middle of the night and lit a grill in the shack we were camped in...
Thank God the kid that stumbled off the balcony didn't get hurt and the noise he made woke us up in time to evac the building with nothing more than nausea and really bad headaches!

IT IS MUCH EASIER TO RUN THE POWER LINE TO THE BUILDING than the exhaust FROM THE BUILDING!
AND SAFER ALSO!
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Sam

trane · Joined: 21 Aug 2008 Posts: 6 Location: fl

Thanks for your reply Sam. I appreciate your concern and probably would offer the same advice! I assure you I do not take any chances or cut corners with safety! I don't know if you read my previous post describing the setting

"It's really not an inside space but rather a poolside area that is shuttered with loosely fitted and bolted temporary aluminum protective panels that have many places for air transfer. To get to this poolside area, you have to exit sealed sliders or doors that exit the home. I've worked with PVC piping many times and always thought the heat from the exhaust would melt it. This exhaust extension that I'm trying to fabricate won't be very complicated and just involve a straight flexible piece horizontally from the muffler (which terminates horizontally) less than 2' through one of the aluminum panels. One consideration will have to be the wind (possibly 50-100 miles per hour at times) blowing against this extension as it exits to the outside that could present a significant back pressure situation periodically. I think I will have to install some sort of omni directional deflector as it terminates to the outside." This is an outside space temporarily shuttered!

I would also like to point out that the very same propane that supplies this generator supplies the fireplace that is vent free and absolutely inside the house which is very tightly sealed, the home is new 2005, and construction plans were approved and all construction phases were inspected by the city! The run I need to make with this is no more than 3 feet horizontally that will penetrate through one of the aluminum shutters.

SamnGlenAllenVa · Joined: 13 Mar 2008 Posts: 154 Location: its in my name

Sounds like you got it all covered. Guess propane is different. Good luck.
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Sam

trane · Joined: 21 Aug 2008 Posts: 6 Location: fl

"Sounds like you got it all covered. Guess propane is different. Good luck."

Sam, I still need to find out where to purchase an exhaust kit. Any ideas?

tantamount · Joined: 15 Apr 2007 Posts: 211 Location: roaming

Sam, I've owned several houses with poolside lanais as trane describes. Trust that there is plenty of ventilation.

.\\ark

SamnGlenAllenVa · Joined: 13 Mar 2008 Posts: 154 Location: its in my name

Yep...lived in Florida and the Keys and over 10 years in Hawaii...
fully understand what you are talking about...just don't want to see anyone hurt or never hurting again.

I grew up on the coast of GA...spent 24 years in various hurricane alleys of the world...Atlantic and Pacific!

Used various generators work and home...

Last emergency was Isabel several years ago...Virginia Beach/Richmond, VA for several types of applications...in both areas...several people KILLED in situations that on the surface seemed reasonble/safe.

We have 3 gens, 1 on wheels @6500 amp, 1 Honda 2000 portable, and the Onan 4000 in the class A.

I could have assembled my own contraption, but just went ahead and bought the Gen-Turi exhaust venting kit...definitely too pricey in my opinion...AND I HAD TO REROUTE and extend the existing pipe... but I felt safe!

BUT STILL am concerned that it vents to slightly above the roof line...BUT IN LINE WITH THE ROOF VENTS AND A/C ...so can't that just be sucked back in?

I am no ENGINEER so I can't be sure, but my experiences/knowledge tell me there are many factors to consider.

HEAT RISES...so I understand the chimney effect of an upright vent

If you are running an extension vertical, then what factors are in place...I would think it needs to be a sealed pipe/outlet...but then the exhaust has to be PUSHED OUT THE PIPE...the system is designed to do only what is as sold as...BACK PRESSURE is mentioned in many places, I don't know the specifics but there may obviously be some type of issue/concern.

My GENTURI instructions showed an extreme extension and said to limit slopes and turns for that very reason, but also implied some concern over length of the run...I DON'T KNOW, but it raises concern on my part as I don't know but wonder why they mention it~~~it must be relative?

NOW~~~I called around to several shops and many auto parts suppliers...
My Onan exhaust pipe was a unique size...

HERE IS WHAT A SHOP ADVISED and I did get several possible options

LOWES/HOME DEPOT....
(1) Chainlink fence material may fit....
(a church member just disassembled one and offered any scrap pipe material I needed)

(2) Electrical conduit...1 1/4" EMT...(which isn't really that size) fit perfectly for my situation...but it only comes in 10' lengths...a plus is it also has pre-bent pieces and connectors available (I believe a smooth curve is less detrimental than a sharp 90-degree turn.
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Sam

SamnGlenAllenVa · Joined: 13 Mar 2008 Posts: 154 Location: its in my name

Because I didn't need 10 feet...or care to spend $20...

I bought a ($5.00) 1 1/2" exhaust straight pipe from NAPA and used excess pipe material to make step-up adapter to fill the gap tween the smaller OD of existing pipe and the ID of the extension pipe before clamping down with the exhaust pipe clamp.

Then I used the supplied Genturi connector.

Apologies for the wordiness...hope this helps!
Good luck
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Sam

trane · Joined: 21 Aug 2008 Posts: 6 Location: fl

HERE IS WHAT A SHOP ADVISED and I did get several possible options

LOWES/HOME DEPOT....
(1) Chainlink fence material may fit....
(a church member just disassembled one and offered any scrap pipe material I needed)

(2) Electrical conduit...1 1/4" EMT...(which isn't really that size) fit perfectly for my situation...but it only comes in 10' lengths...a plus is it also has pre-bent pieces and connectors available (I believe a smooth curve is less detrimental than a sharp 90-degree turn.
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Thanks Sam, never thought of EMT but sounds like a winner! Lightweight, easily available! I just now need a way to connect/secure it to the exhaust outlet on the generator exhaust approximately 3/4" diameter and 1" in length and a transition to 1 1/4". I don't know if EMT fittings are available. Also I was planning to put some sort of an omnidirectional cap on the outside of the shutters where this extension will terminate, so whichever way the wind blows, it will limit back pressure! The developed length of this exhaust extension should only be 3 feet max. I also will locate a carbon monoxide detector in the space during operation to insure levels remain safe!

SamnGlenAllenVa · Joined: 13 Mar 2008 Posts: 154 Location: its in my name

Great!

At Lowes there were several different sizes...may just be the right size if they had the 3/4" or 1" EMT conduit...then again an electrical supply or old-fashioned hardware store may be the gold mine you need!

You don't have to go with the larger tube.

and as far as a rain/wind cap...seems like a "T" connector placed horizontally would probably cover any direction breeze and avoid any wind blowing straight back at it.
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Sam