[RE-wrenches] Modules over vents
Ray Walters
ray at solarray.com
Wed Sep 24 10:37:54 PDT 2014
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
> <mailto: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 <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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