[RE-wrenches] Modules over vents

Dave Click daveclick at fsec.ucf.edu
Wed Sep 24 08:20:06 PDT 2014 

Flipping through the '04 plumbing code I see a few slopes called out 
(1/4" per 1' for fixture vents, 1" per 1' for circuit vents, 1/2" per 1' 
for combination drain/vent...). Fixture vents have a maximum distance of 
a few feet from fixture trap to vent, but I don't think this prevents 
you from then running that vent horizontally. 916.2 states that for 
vents other than stack vents or vent stacks if your vent is >40' you 
need to upsize the whole vent pipe (tough to do for an existing 
building, of course). Stack vents have a "maximum developed length" of 
100' for a 1.5" vent which should be enough space to get away from under 
the PV. I don't see any slope requirements specifically for stack vents 
but my non-plumber's eye may be missing something.

The stack vent sizing Table 916.1 appears (in part) here too and it 
looks like the tables match up to a 2.5":
http://www.engineeringtoolbox.com/drainage-vents-d_1110.html

DKC



On 2014/9/24 10:19, Jason Szumlanski wrote:
> I am unable to find anything in the Florida code that precludes 
> covering a plumbing vent. The code does require the vent to be 6" 
> above the roof surface I believe.
>
> I was unable to determine if these vents need to be vertical with no 
> bends in the attic. Obviously you wouldn't want to create a trap in 
> the attic, but a couple of 45's to relocate a plumbing vent to 
> accommodate more PV seems like a desirable thing to do sometimes. Does 
> anyone know if these can be relocated, i.e. to an adjacent roof surface?
>
> On my own home I had a vent to deal with. I broke out my saws-all, 
> split the lead like a banana and peeled it back, cut the pipe at an 
> angle, and folded the lead back into the pipe after applying sealant 
> between the lead and pipe. There is a 1" gap between the rim of the 
> pipe and the back of the module. My theory on this working safely is 
> that, a) there will be far less rainwater falling in and around this 
> pipe with a module over it, and b) it is about 24" from the roof ridge 
> and there is a module over it so there will be very little water 
> sheeting down from above the vent. Code notwithstanding, I felt this 
> was a solid method on my own home, and I have inspected it after 6 
> months of Florida downpours and found no issues.
>
>
> Jason Szumlanski
>
> Fafco Solar
>
>
> On Wed, Sep 24, 2014 at 6:38 AM, Bill Loesch <solar1online at charter.net 
> <mailto:solar1online at charter.net>> wrote:
>
>
>     Bruce, August, et al,
>
>     This is but one more example of confusing terminology. A plumbing
>     vent is not an exhaust vent!
>
>     A plumbing vent (what August calls a cold vent) is provided to
>     allow the sanitary drain traps (and perhaps more) to operate
>     properly. Without the properly functioning traps you would have
>     sewer gas smell and sewer gas from the plumbing fixtures. This was
>     commonplace when indoor plumbing was introduced to early adopters.
>
>     An exhaust vent is another animal entirely. An exhaust vent
>     carries the combustion products to a suitable exterior location
>     for dilution with ambient air. With the advent of power vented
>     combustion appliances, a direct vent (one that takes in combustion
>     air from the outside and naturally exhausts combustion products to
>     the outside) is IMHO the only responsible way to install any power
>     vented appliance in a freezing climate. (Power vented appliances
>     come in both condensing and non-condensing flavors-they can
>     penetrate the side wall or the roof). Originally, two separate
>     pipes (with two independent properly separated penetrations) was
>     used. That technique is still often used today. More recently
>     concentric vents have been introduced both for condensing and
>     non-condensing applications. A concentric vent can simplify some
>     installations by putting the exhaust pipe inside a larger air
>     intake pipe allowing for one, albeit larger, penetration. As you
>     might imagine if the exhaust flow is hindered/diverted/redirected
>     by an inappropriately located solar module combustion gasses will
>     be re-ingested into the intake air. Not good for equipment
>     performance. My understanding is the power vented _appliance
>     manufacturer_ dictates what kind of separation/clearances are
>     needed with their product. My guess is you find they want at least
>     a foot of separation between the top of the " inverted cone" and
>     the module. Probably not what you had in mind for an aesthetically
>     pleasing installation.
>
>     I hope this helps,
>
>     Bill Loesch
>     Solar 1 - Saint Louis Solar
>     314 631 1094  <tel:314%20631%201094>
>
>     On 23-Sep-14 6:54 PM, August Goers wrote:
>>     Bruce and All, Sorry, I hit send before I had a chance to
>>     complete my thoughts. What I meant to say was that I've found
>>     AHJs often allow us to cover cold plumbing vents but I've never
>>     tried or had any luck with covering hot vents including
>>     condensing boiler PVC vents. Once again, if in doubt you could
>>     see what the plan checker or inspector thinks. Best, August
>>     -----Original Message----- From: August Goers
>>     [mailto:august at luminalt.com] Sent: Tuesday, September 23, 2014
>>     4:15 PM To: 'RE-wrenches' Subject: RE: [RE-wrenches] Modules over
>>     vents Bruce, I'll send you the CA plumbing code vent section
>>     offlist (attachment too large for this list). The way I read the
>>     code is that you technically can't cover any type of plumbing or
>>     hot vent. However, and I've run into little resistance from AHJs
>>     in the Bay Area by covering these. You might want to check in
>>     with your plan checker. Best, August Luminalt -----Original
>>     Message----- From: RE-wrenches
>>     [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of
>>     Bruce Leininger Sent: Tuesday, September 23, 2014 3:49 PM To:
>>     RE-wrenches Subject: [RE-wrenches] Modules over vents Hi all.
>>     We're designing a system on a roof that is literally infested
>>     with plumbing, exhaust and combustion vents. The combustion vents
>>     are PVC and none of the vents are more than 1.5' above the roof.
>>     A racking company says that we can cover them with modules, since
>>     the modules will be at least 4' above the roof. They have not yet
>>     provided any building code references to say that this is ok. Do
>>     any of you know if the building code allows this? Thanks. Bruce
>
>
>
>
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