Plumbing Vent under bathroom sink

LK23 · 04-04-2006, 07:15 PM

The plumbing vent under the bathroom sink leaks oders from the grey tank. This seems to happen most often when we use the ceiling vent fans. Is this plumbing vent necessary or is there a better vent to use?

LK23 · 04-04-2006, 07:15 PM

The plumbing vent under the bathroom sink leaks oders from the grey tank. This seems to happen most often when we use the ceiling vent fans. Is this plumbing vent necessary or is there a better vent to use?

AFChap · 04-04-2006, 08:07 PM

LK23

Are you sure it is the vent under the bathroom sink? ...and the grey tank? ...I think most Winnebago coaches have the bathroom sink plumbed to the black tank. Either way, the vent should not leak odors. It may need a little R&R.

Also, we have found that if we use the rear roof vent while driving, it sucks in odors from the rooftop tank vents.

I have also heard others say their roof vent fans will suck odors out of the tank, particularly when they flush. If you have both vent fans on and no windows open, they have to suck air in somewhere!!! We often open both vents, but have just one fan on. That sucks air in one and out the other. When it gets warmer we turn both fans on and open a window or two.

starchy · 04-05-2006, 01:22 AM

Have you unsrewed the vent and checked the seal. Sometimes these seals get a little dirty and stay in the open position allowing sewer odor to pass through. Carefully clean the rubber seal with hot soapy water and a soft brush then reattach and see if odor is still there. You can also check to see if the vent on the roof is open. Sometimes leaves and other material can clogg this vent. Good luck.

LK23 · 04-05-2006, 06:00 AM

The odor is definitely coming from under the sink. I thought this sink emptied to grey water. I bought a new vent yesterday and will see if that helps. I keep wondering if the vent is necessary.

Rich Bock · 04-05-2006, 06:21 AM

Something is definately wrong here - there shouldn't be a vent under the sink. The drain line, which is probably connected to the shower or kitchen sink as well, should be vented to the roof.

BigTrace · 04-05-2006, 07:16 AM

In some models, the sink is plumbed to the black tank, in some the grey. It depends on the model and whether Winnie thinks the grey tank has enough capacity. My dad's Navion has the bathroom sink plumbed to the black tank, but the kitchen sink and shower go to the grey side. In my Horizon, the Grey's take care of all the sinks and shower while the black tank is strictly for the toilet.

Anyhow, If there is a vent under your sink, more than likely it is a grey tank vent. Also, you DO need the vent for proper backflow pressure like a home sink. The P-Trap in a sink is what normally what keeps the gasses out. If this isn't working properly or has a lot of build up, it could also cause a bad smell through the sink.

rvten · 04-05-2006, 07:19 AM

You can get a replacement vent from any hardware store. Did this in one of my other MH's.

tderonne · 04-05-2006, 08:46 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Rich Bock:
Something is definately wrong here - there shouldn't be a vent under the sink. The drain line, which is probably connected to the shower or kitchen sink as well, should be vented to the roof. </div></BLOCKQUOTE>

Well "vent" isn't the exact right terminology, "air inlet valve" would be more proper. Your coach has four such valves, one for each sink, and one for the washer. At least that's what Winnebago shows in the plumbing diagrams.

(They are often call "Studor" valves. That's a brand name. Studor invented them I'm told.)

Tom N · 04-05-2006, 08:52 AM

These are called a vacuum break. They are a one way valve allowing air in and no air out. If they malfunction they will allow air out and thus an odor. A light tap may be all that is needed.