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Author Topic: Plumbing vents and negative pressure  (Read 6975 times)
belfert
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« Reply #15 on: June 09, 2009, 11:47:48 AM »

I've already added an RV360 vent cover that is supposed to create a venturi effect and it really doesn't help in my case.
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Brian Elfert - 1995 Dina Viaggio 1000 Series 60/B500 - 75% done but usable - Minneapolis, MN
kyle4501
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« Reply #16 on: June 09, 2009, 11:52:04 AM »

If there is excessive negative pressure inside the bus, it ain't gonna matter where the tank is vented (roof or below), it's still gonna pull air inside the coach when the toilet valve is opened.

Before the powered (or venturi) vent will work, it must overcome the negative pressure & still move enough air.


I made the mistake of sealing up the front of mine a little too well, the result being that I was able to smell the engine & exhaust as tho I was right behind it!

Solution may be as simple as opening a window. . . . . or not. . . .


http://www.busconversions.com/bbs/index.php?topic=12131.0   
is the thread where codes were discussed by some & dismissed by others. . . .

Some don't recognise the difference between house toilets & the typical sliding valve rv toilet.
Some think 1.5 liter per flush is minimal water usage where others think 2 cups is excessive. . . . I suppose it's relative. . . .

I would encourage one to understand why the standards are, well standard & widely accepted, before rushing out to invent new methods . . .  Wink
Nothing wrong with outside the box thinking as long as the stuff inside the box is understood first.


Past performance does not guarantee future results. . . .
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Blacksheep
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« Reply #17 on: June 09, 2009, 12:16:08 PM »

Kyle, when you say you made the mistake of sealing your front up too good, what front? Are you thar far ahead with a scenic cause if so we want pics! I thought you always tugged a trailer home. Do they even have a front?
Oh yea another thing. Its ok to use my name in your postings! It will keep you from wording it to just insinuate!

Belfert, go to odorhog.com

Maybe that will help you with your stinking problem! LOL

Ace
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belfert
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« Reply #18 on: June 09, 2009, 01:37:29 PM »

The problem is not odor out of the vent.  I am 95% sure the odor comes through the toilet when it is flushed.

I don't think the OdorHog would help.
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Brian Elfert - 1995 Dina Viaggio 1000 Series 60/B500 - 75% done but usable - Minneapolis, MN
kyle4501
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« Reply #19 on: June 09, 2009, 02:03:12 PM »

OMG! ace, I'm so sorry I forgot to include you in the announcement when I drove one home from Delaware or the one up from Florida! my bad.  Roll Eyes  Tongue

ace, Why on earth would you always assume I was referring to only you. I hate to disappoint, & it may come as a surprise to everyone, but I wasn't thinking about you in particular in that post. you might be surprised to know that you don't rate any higher than anyone else when it comes to what is posted here when I'm reading.  Shocked

Ever read the s&s discussion boards & notice the contempt expressed there for 'rules' concerning:GVWR, tire loads, speed, batteries, etc.? So you aren't alone in your opinions.  Grin

The water use goes back to a time when we had to watch how much water went down the drain (carrying slop jars out every morning. . . . . .) while we were saving up to have the leech fields replaced on the septic system. Also was thinking about how fast a family of 6 can fill a 30 gal waste tank if water isn't watched . . . .

My Grandad emphasized understanding stuff before getting too far outside the box, so he predates your use of the term. Sorry again to disappoint, but he comes to mind even when you say it.  Grin



All kidding & sarcasm aside, before one, anyone, can make the best choice for their needs, they have to look at all sides of the issue & that is what is so great about these discussion boards - all the different ways of looking at opportunities (they aren't problems until it stumps you  Grin ) will enable one to utilize what works best for their situation.


Chill dudes & dudetts, tomorrow is hump day!  Grin Grin Grin
« Last Edit: June 09, 2009, 02:19:15 PM by kyle4501 » Logged

I know you believe you understand what you think I said, but I am not sure you realize that what you heard is not what I meant. (R.M. Nixon)
Blacksheep
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« Reply #20 on: June 09, 2009, 02:31:00 PM »


Kyle...
 my feelings are so hurt!

As for reading the S&S boards? Why in the world would I? Am I missing something there that I cant catch here?

I already knew you have a stable of scenics and they ARE all that from the looks of the one I was lucky enough to go in when at Cliff's house! My guess is that if you haven't started on at least one of them YET, then all you have is a bunch of yard knomes!  Roll Eyes

OTOH if you have started and your on your way, I'm sure we all would love to see your pics of the progress! I mean, it WAS you that said you sealed it up in the front too good referring to your vent and this being a bus board, one would think that you were talking about a bus, not a tugger or S&S!

Then again, you may be just waiting to sell that land and build your dream coach but if that;s the case, it may be a while since the economy is pretty darn lousy these days! I know, I too have land for sale!

You yourself, may want to think about that chill pill too, bud!  Wink

Ace
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Nick Badame Refrig/ACC
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« Reply #21 on: June 09, 2009, 03:25:51 PM »

Ace, Kyle,

It stops here.... take it off the board if ya have to but, this is a final warning before we have to lock down.

Nick-
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« Reply #22 on: June 09, 2009, 03:39:27 PM »

Not meaning to get this back on topic or anything like that but ..............   Grin

We just open a window in the bedroom.  Maybe it smells bad in the bedroom while we are travelling although I honestly don't think it does because if I scoot back there when we stop it doesn't smell bad.  Since the old woman I travel with won't drive and the cat doesn't have an opposable thumb I guess I'll never know.

All I know is:
All the windows closed up - inside smells bad. 
All the windows except the ticket window closed - inside smells REALLY bad, particularly at the front.
Bedroom window open with or without the ticket window open - bus smells good. 
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« Reply #23 on: June 09, 2009, 05:01:57 PM »

I never had a smell in the bus, until I notice that the toilet hose was not sealed on the outside of the hose.  I RTV'd the outside of the hose, just to seal it up.  NOW!  I have a smell, have played with opening closing windows, that helps a little.  Wonder what will happen is I crack the bay door open a bit.

I like the floor vent.

Bill
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belfert
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« Reply #24 on: June 09, 2009, 05:17:19 PM »

As far as the negative pressure inside the bus goes, that is just speculation from a forum posting last year about this.


I know my bus is way less than air tight up front due to how Dina designed the front end.
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Brian Elfert - 1995 Dina Viaggio 1000 Series 60/B500 - 75% done but usable - Minneapolis, MN
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« Reply #25 on: June 09, 2009, 05:50:10 PM »

As far as the suction/pressure inside the coach that is drawing tank odours inside...

The forces involved in hurtling the coach through the air at highway speed will not be overcome by way of fans.

And as noted, trying to ramp up the suction to the tanks to compete tends to suck the traps dry, leading to stink when you slow down...

Either the coach has a suction, or the tank has a pressure....

see bob's solution. weaken your opponent. But note, opening the wrong window makes it worse!

Relieve the pressures, or figure out how they are building in the first place. What vents/intakes/exhausts were closed off during the conversion process?

By design, a highway coach went down the road with positive pressure inside.

Is the tank vent located unwittingly in a high pressure location in the coach slipstream? A venturi won't do much if located in the midst of a higher pressure environment.

Find the cause, don't spend money treating symptoms!

happy coaching!
buswarrior
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belfert
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« Reply #26 on: June 09, 2009, 05:55:40 PM »

The vent is located maybe a foot off the center of the roof.  I'm neither an aerodynamics engineer nor a plumbing engineer so I am not sure how to solve the problem instead of merely the symptom.
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Brian Elfert - 1995 Dina Viaggio 1000 Series 60/B500 - 75% done but usable - Minneapolis, MN
Chopper Scott
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« Reply #27 on: June 09, 2009, 06:56:19 PM »

I had that same problem but found a rather strange cure. We ran out of cheese. Once we quit eating so much cheese the smell went away.  Cheesy Cheesy Now when we eat a lot of cheese we use rest areas, truck stops and neighbor's lawns for our more strenuous daily duties!   Grin  Actually on a more constructive note isn't there a 2 way type sewer vent that is made for such problems. Basically it is for basements with the laundry and or bathrooms downstairs. I'll check with a plumber buddy I have if I see him tomorrow. I know he has used them a lot for situations when the traps keep getting sucked dry. Later
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« Reply #28 on: June 09, 2009, 07:03:25 PM »

Hey Brian
Let's try working on the problem a step or two at a time.
You say you have the smell when going down the road. Does this mean when parked, there is no smell?
Have you noticed if it makes a difference which direction the wind is relative to the coach when the smell is present, i.e left front quartering wind-smell but no smell with a right quartering tailwind, etc.?
You say you have tried the vent fan and it made no difference. Brian, try this experiment to see what results it produces, unless you already know. Run the vent fan, all coach windows closed while moving, then flush the toilet. Does the smell worsen or truely, there is no difference either way, vent fan on or off?
Try this experiment, open all the windows in the coach, flush the toilet, smell or no smell. If no smell, then close a window at a time until you notice the smell, if at all.
Some "engineering" questions also for you. What size vent pipe did you use? How many elbows are in the run from the tank to the roof? Reason, a short radius 90 degree elbow decreases flow by 25%. Four of these in a vent stack causes the air flow to be zero acting as if there were no vent stack at all. Long sweeps are not as bad at about 15% each. Virtually everyone has one elbow coming out of the tank from horizontal to vertical, then varies from there.
Baffled tank or not? Was the tank ever over full such that the "TP" floated up the vent stack and stopped it up or have you tried making sure the vent stack is open to the tank?

Let us know the answers to these questions and see where we go from here.

Rob
91 Prevost LeMirage XL
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Blacksheep
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« Reply #29 on: June 09, 2009, 07:38:22 PM »

Scott I believe what your referring to is called a "studor" valve or vent! Might even be known as an "air admittance valve".

Works very well where you CAN'T have a vent in a room going up thru a roof or even in a particular room. They use them a lot on island cabinets with sinks or maybe like a bar type cabinet with a sink!

HD has them and they run about 20 bucks. PVC and fits I think a 2 inch pipe.
Ace
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