[RE-wrenches] Modules over vents

Matt Partymiller matt at solar-energy-solutions.com
Thu Sep 25 05:22:58 PDT 2014


Carl,

In our shared region plumbing code requires vents be 12" above roof line. 
Electrical inspectors probably won't catch this, plumbing inspectors
probably won't get on a roof, but still there is a code concern.  You
might exercise some caution.

Matt


Matthew Partymiller
Solar Energy Solutions LLC
(877) 312-7456
matt at solar-energy-solutions.com

On Wed, September 24, 2014 6:49 pm, Carl Adams wrote:
> Bruce,
> We routinely cut off DWV as suggested by earlier posts so that they are at
> least 1 inch below the surface of the back of the module.
>
> To be clear these are sewage intake air vents and not exhaust vents for
> heating appliances.
>
> We do place a quarter inch wire cloth over the cut off vent and apply a
> four inch stainless steel hose clamp around the pipe just to prevent
> foreign objects from entering the vent pipe.
>
> I have never had an inspector question this method.
>
>
> With Regards
> Carl Adams, President
> SunRock Solar
> 513.290.9072 (cell)
> 513.766.6025 (office)
>
>
> On Sep 24, 2014, at 1:37 PM, Ray Walters <ray at solarray.com> wrote:
>
>
> I agree with Kurt: you need a licensed       plumber in your area to
> advise you, if you're trying to keep the AHJs happy . 2nd,  I'm very sure
> you don't want an exhaust/ combustion type vent under the array.  I've
> had several over the years, and seen some arrays installed over them.
> They can get fairly hot and put quite a bit of steam out.  I would not
> trust the module backing material to a concentrated long term dose; which
> module is going to have a problem first? R.Ray Walters
> CTO, Solarray, Inc
> Nabcep Certified PV Installer,
> Licensed Master Electrician
> Solar Design Engineer
> 303 505-8760
> On 9/24/2014 11:16 AM, Kurt Johnsen wrote:
>
>> Should you decide to lower your plumbing vents I have found an inside
>> pipe cutter to be an inexpensive and handy tool. Cut the vent and lead
>> off an inch above your desired pipe height and use the inside cutter to
>> cut the pvc pipe. Go slow and be careful to keep air space between the
>> pvc and lead as the lead will cut very easily.
>>
>>
>>
>> Also I wouldn't rely on us well intentioned wrenches to make the call
>> on the plumbing code in your jurisdiction. Though the state plumbing
>> codes are usually based on the international code, there will be
>> differences. If you can't pull up your state plumbing code online then
>> ask your plumbing inspector. In Florida the minimum height above a roof
>> surface is 6" (904.1). As for relocating 905.2 states that “all vent
>> and branch vent pipes shall be so graded and connected as to drain back
>> to the drainage pipe by gravity”. Table 710.1(1) shows that for
>> 1.5” pipe a slope of ¼” per foot is sufficient to handle 3
>> fixtures. I would take that to indicate ¼” / foot is plenty for a
>> 1.5” vent.
>>
>>
>>
>>> On Wed, Sep 24, 2014 at 11:20 AM, Dave Click <daveclick at fsec.ucf.edu>
>>> wrote:
>>> 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> 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
>>>>> 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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