[RE-wrenches] Modules over vents
Carl Adams
swingjunkie at gmail.com
Wed Sep 24 15:49:44 PDT 2014
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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