Replies

1. 
   jackplane | Feb 27, 2003 09:00pm | #1

   Thanks,maybe an inspector can shed some enlightenment here for both questions.

2. 
   Ward | Feb 27, 2003 09:44pm | #2

   Not a good idea.

   The dryer could force sewer gases back thru the fan, & v/v.  Yes, they may have check flappers, but those are not very air tight. 

   Worse yet, on a very windy day, the positive air pressure outside could let sewer gases migrate through both vents.

   Plant a nice shrub by the dryer vent and place the others on the back of the house.

3. 
   BossHog | Feb 27, 2003 10:33pm | #3

   Ward is right - Bad idea.

   Age is not a particularly interesting subject. Anyone can get old. All you have to do is live long enough.

1. 
   jackplane | Feb 27, 2003 10:38pm | #4

   Thank you ,Ward et al.I guess I'll go blast more holes thru the roof.I sure don't want my clothes out of the dryer smelling like sewer gases.

1. 
   Ward | Feb 27, 2003 11:48pm | #5

   Please don't offend the plumbers, they think that smell turns their wives on.

4. 
   JeffBuck | Feb 28, 2003 01:11am | #6

   holes thru the roof.....done right.......aren't a problem.......especially vent stack boots.

   I've seen more chimney flashing leak that stack boots.

   Jeff

   Buck Construction   Pittsburgh,PA

    Fine Carpentery.....While U Waite                  

5. 
   DouglasA | Feb 28, 2003 02:37am | #7

   As an insepctor, your question about venting shows a lack of understanding. You may never interconnect vent system of differing types.  Plumbing systems are not be connected to any other systems what so ever.  Mechancial venting systems (bath fan vent) are not to be connected to air-handling (heating/ac ducts) systems, etc.  Appliance exhaust vents (furnace, waterheater, etc.) for discharge of products of combustion may be connected but only for the same category of equipment (Gravity vents to gravity vents, etc.) except in specific engineered designs for certain power exhaust.  See GAMA or AGA tables & notes on interconnected systems.  However, never connect these vents to any solid fuel burning appliances.

   Equipment vents for dryers are not to be connected to any other equipment, read the manufacturer's instructions.  Especially a washing machine as this is a plumbing vent and a dryer is a mechanical vent.  Also for information, check the instructions on the dryer vent type, length and direction.  I don't know of any dryer vents that a permitted to go vertical for more than about 6-feet.

   One of the other respondents to this message made a good statement by saying, A hole through the roof when done correctly is no problem... but it must be maintained.

   Hope this helps.....

1. 
   Bruce | Feb 28, 2003 08:05am | #8

   Let me take this opportunity, having an inspector here and all, to ask another questio about combining vents ... only in this case they would all be plumbing.  I'm doing a flat-roofed project, and want to minimize penetrations 1) for the obvious reason, fewer potential leaks, and 2) because the roof will be visible to a row of houses higher up the hillside, and I'd like to keep the roof as clear as possible.

   Can I gang up vents from each bathroom, combining them into one larger vent that penetrates the roof?  If so, does that vent have to equal the area of all the other individual vents?  Example ... a shower drain, a toilet, and a lav (or 2) all combined into one 3" or 4" vent?

   Could I go so far as to vent the single pipe through a clamshell vent on the backside of the parapet wall, thus doing away entirely with a penetration in the horizontal surface of the membrane?

1. 
   bmozee | Feb 28, 2003 08:16am | #9

   Will also let the experts reply here, but combining them all has never been a problem.  Don't feel like you have to combine the sizes, remember you're just venting gases.  Combine into one 3" and you should be fine, remember to slope horizontal runs downhill (sounds obvious doesn't it?).

1. 
   BossHog | Feb 28, 2003 04:36pm | #12

   The fact that you've apparently gotten away with doing something stupid doesn't mean it's a good idea for anyone else to do it.It is easier to get older than it is to get wiser.

1. 
   rjw | Feb 28, 2003 05:38pm | #14

   BH, I think  in the msg you were responding to he was talking about just joining the plumbing waste vent stacks together.

   That's the way I read it but his message was ambiguous - he could hve meant the waste vent stacks and the fan vent._______________________

   "I may have said the same thing before... But my explanation, I am sure, will always be different."  Oscar Wilde

2. 
   BossHog | Feb 28, 2003 06:16pm | #16

   When he said "combining them all has never been a problem." I took it to mean all types of vents since that was the original question. But you're right - It's possible he only meant plumbing.

   Maybe he'll stop back by the thread and let us know.I have my doubts about disbelief.

3. 
   bmozee | Mar 03, 2003 01:11am | #19

   Sorry guys to not be so clear on the matter.  I was in fact talking about only the plumbing vents.  I would never combine any other vents in with plumbing ones.  I don't even combine bathroom vents (except when using a central fan that does more than one room at a time), much less a dryer vent with ANYTHING else....

4. 
   bmozee | Mar 03, 2003 01:16am | #20

   Hey Boss..go back and please read the message I was responding to.  It wasn't the first one in the series, but one that was talking about plumbing vents.  Just to set the record straight!

5. 
   BossHog | Mar 03, 2003 01:26am | #21

   Well, you're right - I missed that. But you can't expect me to be brilliant AND good looking....................(-:I'm really easy to get along with once you people learn to worship me.

6. 
   bmozee | Mar 03, 2003 01:34am | #22

   Yeah, but down here...."Looks are everything".  Along the same lines, I've heard it said, "If you can't do it right, at least make it look good."

   Thanks for reply...Bill

2. 
   rjw | Feb 28, 2003 03:54pm | #11

   Vent sizing and positioning is dictated by codes.  Use 'em.

   BTW, the waste vents not only vent sewer gases, but (more importantly, perhaps?) equalize pressures in the waste kines so a slug of water draining down a waste pipe doesn't poll a vacuum behind it and suck water ouit of the traps.

   BTW/FWIW, attached is a pic from a couple of weeks ago of frost trying to seal off a vent at the top.  This was taken after a week or so of temps well below freezing and close to 0 at times in NW Ohio_______________________

   "I may have said the same thing before... But my explanation, I am sure, will always be different."  Oscar Wilde

   
3. 
   DouglasA | Feb 28, 2003 07:02pm | #17

   You can gang venting on plumbing systems but they must be sized accordingly.  Be to layout a isometric skematic and take to the local plumbing inspectors.  Good explanation on the standard sizing and gang connections can be found the International Plumbing code or the Uniform Plumbing Code (note there may be a local code or variation to these that is why best to check with local inspectors).

   Venting plumbing in the horizontal is permitted in most codes except in engineered systems as the potential for blockage in increased from critters.  Also check the terminal location from other structures above.  There is a minimum of 10'-0 offset from building but I would suggest getting it as far away from the other buildings as possible. 

   Hope this helps....

2. 
   Remodeler | Feb 28, 2003 05:34pm | #13

   Bob,

   >Appliance exhaust vents (furnace, waterheater, etc.) for discharge of products of >combustion may be connected but only for the same category of equipment (Gravity >vents to gravity vents, etc.) except in specific engineered designs for certain power >exhaust.  See GAMA or AGA tables & notes on interconnected systems. 

   I did not realize this was code, and did this recently on a remodel (powervent furnace installed horizontally and aquastar ng hwh gravity-vented into an 8" chimney stack).  I am licensed gc and have taken several code classes, so it wasn't done for just being stupid.  Can you elaborate on the why / potential problems?  I would have a devil of a time going back and fixing it. 

   >However, never connect these vents to any solid fuel burning appliances.

   I've always known this was code and never been tempted to do it, but I can see situations where someone would be tempted and am curious why this is a bad idea.  Combustion gases coming back through the fireplace/wb stove?

   thank you,

   remodeler

1. 
   rjw | Feb 28, 2003 05:49pm | #15

   did this recently on a remodel (powervent furnace installed horizontally and aquastar ng hwh gravity-vented into an 8" chimney stack). 

   There are specific code requirements which differ from place to place and the type of equipment.

   If by "powervent" you mean an induced draft 80+ furnace, what you did is probably OK if you used a Y and not a Tee to join the two and if you used the right sizes and lengths.

   BTW, if it is an 80+, it's not a "powervent" - the draft inducer does not push flue gases through the flue, it pulls air and combustion gases, and regulates their flow,  through the combustion chamber.

   Sometimes the 80+ will be misadjusted, though, and pressurize the flue, and if the water heater is connected furnace flue gases might actually be pushed down to the water heater and "back draft" there; or, the flow of furnace flue gases might create an air curtain effect at the T and block the water heater flue gases and cause spillage.

   Since flue gases can kill, and there are complex issues, I suggest people don't mess around with them until they know what the heck they are doing.

   It's one thing for the homeowner to try for a Darwin award; it's another thing for a contractor or service person to try for a manslaughter conviction.

   Even following the codes and charts doesn't guarantee proper operation; my view is that if you haven't performance-tested the thing you haven't done your job, but that's just an opinion._______________________

   "I may have said the same thing before... But my explanation, I am sure, will always be different."  Oscar Wilde

2. 
   DouglasA | Feb 28, 2003 07:09pm | #18

   Your question on power vents and gravity vents is a matter of engineering the area needed for the gases during power up and operations.  The gravity vent does not have the necessary force to override the power vent and therefore may be a problem.  Venting both into a clear area chimney and the standards therefore are found the the exceptions to the GAMA & AGA Vent Tables (Same as NFIPA 54 & International or Uniform Mechanical Codes). 

   Manufacturer's sometimes have standards which indicate they are not to connect to gravity systems.  If you furnace is a Category IV unit (90% efficient or higher) the venting systems cannot be connected with gravity vents due to proximity of the intake and exhaust may be via the same piping.  Check the installation instructions thoroughly.

6. 
   bmozee | Feb 28, 2003 08:19am | #10

   Also not a good idea for the dryer to vent through a 3" pipe, needs at least 4".  I found this out the hard way on a friend's house.  Clothes taking forever to dry, new dryer, etc.  Went back and put in 4" metal (only way to go) and dryer has worked great since.