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Topic: How to check & clean holding tank vent pipes? (Read 1017 times) previous topic - next topic

How to check & clean holding tank vent pipes?

We are suffering from "stinky coach syndrome".
It was strongest under the sink in the bathroom. Replacing the black plastic vacuum breaker under that cabinet seems to have fixed the problem there. But now the same smell is strongest under the counter (between sink and cook top; especially when we open drawers). Vacuum breaker for kitchen sink is back behind those drawers and after replacing it we still have the odor.
I would like to try cleaning the pipes that vent the holding tanks to the roof, but am not sure what to expect if I use a water hose down them??
There are two vents visible on the roof, one on passenger side. I don't know which is which, but I would like to just do the gray water tank. The odors seem like gray water tank, not black. The vent caps are short horizontal pvc shaped and I think I will need to remove them to get a hose down the pipe.
Any suggestions? Possible problems?
Thanks, Dick
Dick, '03 U320 40' Tag, 2 slides, Coach #6075
Full Timers
2009 Honda CR-V

Re: How to check & clean holding tank vent pipes?

Reply #1 –
The vent for the black tank should be very close to the toilet.  The one for the gray tank not so close. It could be anywhere over the gray tank or behind a sink or shower or even the drain run to a sink or shower, any path between the tank or any drain line and the roof will do.

Running water down the vent should only add water to the tank if all is working well, but don't overdo things and have your tank runneth over. If a vacuum breaker is broken and/or the vent clogged near the tank, it might allow some of your down-the-vent water inside the coach.
Tom Lang K6PG (originally  KC6UEC)
and Diane Lang
2003 38 U295 build 6209
2016 Jeep Grand Cherokee Summit Ecodiesel
still have tow-ready 2006 Acura MDX 
Temple City, California
Motorcade 16681 California Chapter President
SKP 16663 member of SKP Park of the Sierra, Coarsegold California
FMCA F071251
Retired electrical and electronic engineer

Re: How to check & clean holding tank vent pipes?

Reply #2 –
Does the bathroom sink drain into the black water holding tank or the gray?
Dick, '03 U320 40' Tag, 2 slides, Coach #6075
Full Timers
2009 Honda CR-V

Re: How to check & clean holding tank vent pipes?

Reply #3 –
I found the source of our odor; it is the in-line vent for the kitchen sink that is located way behind the drawers and that we just replaced a couple weeks ago. We were able to prove it by taping a thin plastic bag over that vent and as much of the pipe as possible, closing all the windows, and turning on a couple fans. That little bet of negative pressure caused the bag to inflate immediately. Then I removed the vent and replaced it with a solid plug and repeated the test; this time the bag did not inflate.
My question: is the in-line vent defective or is there another explanation? Will it cause any problems just leaving the solid plug in place?
It has been so warm here in east Texas that we have had the A/C on most of the time and it keeps a positive pressure inside, so no odor. It mostly occurred in the early morning while cooking breakfast with the hood fan on and of course A/C not on yet. Very frustrating.
Dick, '03 U320 40' Tag, 2 slides, Coach #6075
Full Timers
2009 Honda CR-V

Re: How to check & clean holding tank vent pipes?

Reply #4 –
Dick, it sure sounds like the new vacuum breaker is not working. I would try another one.
The selected media item is not currently available.Kent Speers
Locust Grove, OK
1993 U300 SSE 40' (Restored at FOT 2009) Build 4323
720 watts Solar
6V92TA DDEC Silver Engine
2014 Subaru Outback

Re: How to check & clean holding tank vent pipes?

Reply #5 –
Quote from: Dick S –
I found the source of our odor; it is the in-line vent for the kitchen sink that is located way behind the drawers and that we just replaced a couple weeks ago. We were able to prove it by taping a thin plastic bag over that vent and as much of the pipe as possible, closing all the windows, and turning on a couple fans. That little bet of negative pressure caused the bag to inflate immediately.

It mostly occurred in the early morning while cooking breakfast with the hood fan on and of course A/C not on yet. Very frustrating.

Dick,

It's possible the rubber seal on the new admittance valve isn't sealing well or is weak, but I'm suspecting it might just be a case of "well sealed coach".  We've learned from another member that in order for the venting of the convection oven to work, the little kitchen window needs to be open a little.  Similarly, we find the bath area gets a tad stinky if the Fantastic Fan is running without some source of fresh air make up (particularly if the fan is running when the black tank is being dumped)

You could try another brand or style of admittance valve if it fits (Studor are supposedly high quality, but the ones I've seen are much larger diameter than the inexpensive black ones).

Try opening that kitchen window just an inch or so next time you run the kitchen fan and see if that is a workable solution.

Michelle

ETA - it looks like Studor's Redi-Vent, 20349 for ABS connection, might work if you can find one.

http://www.studor.com/products/redi-vent/RediSpecSheet.pdf

Studor Mini-Vent, 20300 for ABS, might fit as well, but is larger diameter.  http://www.plumbersurplus.com/pdf/07427.pdf
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: How to check & clean holding tank vent pipes?

Reply #6 –
My coach has been in the garage since Jan. and it started the foul smell, I thought it was the black tank, so I OD'd it with the chemical, no help. the black tank is total empty.  have about 10% in grey tank, when I dumped, it was clear that the grey tank had the foul smell, so I flushed it twice, now nice zero smells.  Maybe I need to get into the breaker issue, never have.
Dave M

Re: How to check & clean holding tank vent pipes?

Reply #7 –
Quote
Will it cause any problems just leaving the solid plug in place?
It should cause the drain its attached to drain slower. 

The purpose of the valve (other than replace a roof penetration) is to allow air to be drawn into the pipe to allow the water to drain, otherwise its like trying to drain water out of a hose with your thumb over one end, or water out of a bottle by turning it upside down.  It will work, but will be slow or "burp" its way down.
2000 / 36' / U320 / WTFE
WildEBeest / "Striving to put right what once went wrong"

Re: How to check & clean holding tank vent pipes?

Reply #8 –
Thanks Steve for explaining how this thing works. I was thinking gases from the tank built pressure which was relieved by this vent. Now it makes sense. I'll leave the plug in until we get back to FT on Friday. Then I'll get a new one from Parts and try that. I got one from them for under the bathroom sink and it has worked fine. Got this one from Lowe's to save a buck. :(
Dick, '03 U320 40' Tag, 2 slides, Coach #6075
Full Timers
2009 Honda CR-V

Re: How to check & clean holding tank vent pipes?

Reply #9 –
Not sure it makes any difference but aren't our pipes PVC (black)?
jor
93 225
95 300
97 270
99 320

Re: How to check & clean holding tank vent pipes?

Reply #10 –
jor,

I seem to recall our waste pipes are ABS.  I know Steve had to repair one behind the washer/dryer a year or so ago and I'm pretty sure it was ABS.  Isn't PVC white?

Michelle
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: How to check & clean holding tank vent pipes?

Reply #11 –
Dick,

The bathroom sink drains into the gray tank, at least in my U280. I had to replace that black valve under the bathroom sink in order to eliminate odor just last summer. Got my replacement from Lowes. Fortunately it eliminated the problem, although when the bath vent fan is on we get a few "reminders" occasionally.
Don Hay
'92 Grandvilla, U-280
The Hayfever Express
Build #4055
'97 GEO Tracker
Life is like licking honey off a thorn.
 

Re: How to check & clean holding tank vent pipes?

Reply #12 –
I replaced all the back vent s last year after ayear of the stinky syndrome and scratching my head trying to find it. I took them apart and the rubber diapraghms were distorted and loads of junk on them. I replaced with the better style but went one step further for the shower one under the corner cabinet (behind toilet on my model).
I drilled a hole thru the side of coach so it would enter under the pedistal the toilet sits on, and put a plastic round vent cover in it (with fine holes in) and then glued a Washing Machine/dryer vent cover over it to strop rain etc entering. This was then painted to match coach. It has worked well in allowing a small amount of fresh air in for the valve to properly activate so you do not have to have a window or vent open. No more problems. I have 2 vents in the bathroom, one under the sink and then this other one hidden under this corner cabinet below the bottom shelf (which I had to cut out to get to it). Jor, as your coach is close to mine in age you may have another like me to service the shower only.
John H
Coachless, now use aircraft. 2003 Ford Travelair TC280 class C. Super shape. Just for 1 yr .
1994 Ford E350 ClassC,total renovation inside and out. Now sold.
2000 U295  36' Cummins 350 c/w Banks Stinger, Resonator upgrade,Solar, LED lites.Residential fridge with slide out pantry. Build 5674. Sold
ex 92 GV 022C ored Cummins. Sold
ex 95 GV240 cat 3116. Sold
2017 Mini cooper s & 2016 land Rover LR2 HSE  LUX.
jhaygarth@aol.com    SKP #130098
treat everyone as you would like to be.