Exhaust on a powertech generator with enclosure - How to?

[belfert]

I was checking my bus out today as I am getting ready for my trip in eight weeks.  I noticed the generator exhaust has fallen off.  It was simply clamped around a threaded nipple.  I check it and make sure it is tight every year so I am surprised it came off.  The previous exhaust was just a piece of 1-1/4" exhaust pipe about 36" long with a bend on one end and expanded to fit over the pipe nipple.  It was held on with an exhaust clamp.  It just hung there with no hanger.

I am looking for new ideas on doing the exhaust.  My Powertech generator has an enclosure and the exhaust comes out the bottom.  (Muffler is inside enclosure.)  The exhaust port is a threaded hole 1-1/4" NPT.  I currently have a pipe nipple in there and I am having issues getting the pipe nipple to come out.  The generator rolls out on a slide, so I can't really mount to the bottom of the bus.  Thank you for any ideas in advance.

[oltrunt]

My genny is in a slide out drawer so I threaded a black iron coupling fitting from Lowe's to the exhaust and disconnect it when I need to roll the drawer out.  It takes less than a minute to connect/disconnect and follows my favorite rule:  KISS.  Jack

[luvrbus]

Most use a flex mesh type stainless pipe with 1 v band clamp with 1 bolt 

[belfert]

My genny is in a slide out drawer so I threaded a black iron coupling fitting from Lowe's to the exhaust and disconnect it when I need to roll the drawer out.  It takes less than a minute to connect/disconnect and follows my favorite rule:  KISS.  Jack

Can you take a picture of what you did and post it here please?

[oltrunt]

Will do Brian.  We are out and about in the bus right now, but I'll post a couple of pics later today.  Jack

[oltrunt]

Brian, I'll try not to blather too much.  I'll start with a sketch of my genny lay out and then a few pictures to further confuse the issue.  Although the pics show the genny muffler still directly attached to the genny, I later moved it to a remote location to better control heat build up in the drawer.  I'm sure you can find a more convenient location for the union than I did since your genny is in one of the bays.  Hope this helps.  Jack


Sketch.



I started out by finding a place to hang my Yamaha 3000 W genny.  I eventually tossed the original genny case and moved the control panel to a remote location inside the bus.


I then built a drawer--------


and dropped the genny in (less controls),


I used stainless steel flex tubing from the exhaust port on the genny to the union and thin wall tubing from there on.


A pic of the pipe union.


I ended up with the union located under the bus which is a little inconvenient but there was no space elsewhere.  The picture shows the union wrapped in heat tape which greatly reduces the heat load under the bus floor.  The genny muffler shows to the left.

[digesterman]

Oltrunt is that a gas generator? If so are you comfortable with a gasoline engine on your bus? Just wondering

[belfert]

Brian, I'll try not to blather too much.  I'll start with a sketch of my genny lay out and then a few pictures to further confuse the issue.  Although the pics show the genny muffler still directly attached to the genny, I later moved it to a remote location to better control heat build up in the drawer.  I'm sure you can find a more convenient location for the union than I did since your genny is in one of the bays.  Hope this helps.  Jack

Now I understand.  Your exhaust goes out to the opposite side of the bus so a union works.  Before it fell off my exhaust went out the same side of the bus the generator is mounted on.  An union really won't work unless I route the exhaust a totally different direction.  I don't to go out the other side of the bus as that is the side where everyone congregates when we are camping.  I'm not sure if the engine on the generator would like it if I ran 20 feet of exhaust to the rear of the bus.

One thought I am having right now is to add a thread elbow to the existing nipple and then just run the exhaust out the side that way.  I would put a roller of some sort for the exhaust pipe to roll out with the generator.

[belfert]

Does regular black pipe or galvanized pipe work for exhaust pipe?

[oltrunt]

Digesterman.  Yup it's gas----but--  I don't run it while the bus is moving or when I am not in attendance.  Also, the genny has a remote gas tank and is fed through a metal pipe via an electric fuel pump.  The pump is operated through a relay and allowed to run only if the cooling fan is operating, the genny engine is running, and the temp in the drawer is not in excess of 165 degrees F.  I placed redundant 190 degree F thermostatic switches in (on) the valley at the bottom of the cylinder which ground the magnito in the event the engine block reaches that temp.  I also extended the float bowl overflow tube to extend outside of the drawer and box so if the float sticks the extra fuel does not build up in the drawer/box.  Having heard some horror stories about the float sticking on this model genny, I did some experimentation with trying to get the float to stick.  I found that the float drop as delivered from the mfg allowed the float to drop past center when the float bowl was empty if the genny was tilted in any direction over about 50 degrees ( I determined this by removing the carb and making trials using mineral spirits) so it is a concern.  I put  a stop in the float bowl to keep the float from dropping too far and tested again with satisfactory results.  I just acquired a thermostatically controlled petroleum fire extinguisher and plan to add it to the genny drawer.

Thanks for asking the question.  It gives me a chance to hear any suggestions anyone might have as to what else I might do to make this thing as safe as possible.  I am happy with the performance of the genny so far and in particular it's 53dB noise level.
Jack



This is meant for a boat bilge.  I'll bet it makes a mess!

[oltrunt]

Belfert, either will work just fine but both are overkill.  Plain old mild steel pipe (for exhaust pipe) is OK with aluminized or galvanized being better.  As to the length, as long as you don't have a bunch of twists and kinks all will be well.  On a side note, when I was studying noise suppression in small motors I learned that the exhaust system as a whole should have a diameter not larger than the port at the engine.  For quiet operation these little engines need some back pressure to self cancel their racket.  Fun stuff to read though a bit heavy on the math .  JHack

[belfert]

The reason to use threaded pipe instead of exhaust pipe is because Powertech already has a threaded exhaust outlet on the bottom of the generator.  I have to install something threaded no matter what to get started.

[sledhead]

wow ! 53 db that is awesome what model # is your yamaha gene

thanks   dave

[oltrunt]

Sledhead, it is a Yamaha EF3000iSEB