Cleaning out the vent hose

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T

Terri

Peggy What a great service --- thanks for your time! My question, in short --- can I clean out a gunkified vent hose by flushing it with something (K.O.?) rather than change it out (I cannot see how in gods name I can get to the hose to change it out with my boat's construction). I don't think it is permeated/odiferous, it just has "floaties" up in it from overfilling in the past. The boat has the normal vent 5/8" line from the top of the tank up about 4' to a hull side vent. There is also a manual pump out line with a vent and a large valve on it (as well as a siphon break). A guest closed the big red valve on the manual pump line, and apparently took away our venting capacity as subsequent flushes of the Raritan PHII pressurized the holding tank....it lifted the cabin floor on the boat....when I noted it, I opened the valve on the overboard pump line and the ensuing "wet fart" was a site to behold.....but the cabin floor went down. (As an aside, no sign at all of holding tank leaking from the "pressure test".....whew). I think this saga tells me that the vent line is effectively plugged, and our venting is happening via the manual overboard pump line and siphon break. This is nice and big, so we have great airflow, but............ How can I clean out the vent line?
 

CalebD

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Jun 27, 2006
1,479
Tartan 27' 1967 Nyack, NY
You are on to some of the first things to try

This sounds like a potentially messy and stinky situation: if your vent hose is clogged you cannot expect to empty your holding tank properly and will continue to have nothing but more problems. I think the first liquid you should put down your vent hose is a little vinegar (acetic acid) which is supposed to help calcified buildups that occur in head systems. Add a little water to the white vinegar before putting a few ounces into the vent outlet as well. Let it work for a few hours. If there are no >90 degree turns in your vent pipe you might be able to use some kind of wire to "snake" out the hose mechanically and carefully. Otherwise you should prepare for the possibility of having to replace this hose if it should break with its precious cargo inside that could spill nicely into your bilge. The product KO is great for flushing into the tank to 'kill odors' and is bacterial in nature but is not an acid like acetic acid (vinegar) which will slowly eat away at calcium and other deposits. This is a fairy dangerous accident waiting to happen and you really should avoid making your holding tank "wet fart" out of your boat in most waters you and I like to be on. Peggy's book is also a great reference for all of this. Peggy? Good luck with clearing that holding tank vent.
 

GuyT

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May 8, 2007
406
Hunter 34 South Amboy, NJ
Cleaning vent hose

Disconnect both ends of the vent hose - tank and thru hull. If you run a snake line all the way through your vent hose you can then pull a cloth attached to the snake line through the vent hose to clear the debris. Heavy weed wack line is very strong and you will be fish that thru the 5/8 inch hose from end to end. You can get that at Home Depot. You may want to do this several times - and increase your cloth size. You may also want to rig a push pull system(cloth in the middle of two snake lines) so you can get some additional wiping action from the cloth. Just dont get your cloth stuck in the hose!
 
Dec 2, 1997
8,958
- - LIttle Rock
IMO, it would be easier to replace the vent line

If you can get to both ends to disconnect it from the tank and the thru-hull, you don't need to access anything else...you can connect the new hose to the old and pull it through as you pull the old vent line out. Use a male-male connector...cut the ends of the new and old hose as cleanly as possible...you want to be able to butt them tightly together to create the smoothest unbroken surface possible. Use PVC cement to glue the hoses onto the connector...clamps will get hung up, duct tape won't keep 'em on the connector if you have to pull hard, and the last thing you want is for 'em to come apart in an inaccessible area. Clean out the vent thru-hull and the tank fitting. In fact, if your vent thru-hull is one that doesn't allow you to backflush it with a hose--which you should do every time you pump out and/or wash the boat--this would be a good time to replace it with one that does. Apparently your vent line has been totally blocked for some time, making the air valve on your vented loop the only source/escape for air in the tank till a guest closed it too. What surprises me is that nobody noticed that the toilet was becoming harder and harder to pump as the tank became increasingly pressurized--SO pressurized that you don't want to know how close it was to bursting...or equally bad--erupting through the toilet. Attempting to pump out against a blocked vent can also crack a tank...so it's essential that tank vents be checked regularly and kept clear. You're just lucky that your vented loop has the type of air valve it does...'cuz otherwise I think you'd have had a major disaster long before your guest closed it. ANY time a toilet starts to become harder to pump, STOP USING IT!!! 'Cuz that means something is wrong--a blocked tank vent...clog...that has to corrected if you don't want major problems.
 
Dec 25, 2000
5,940
Hunter Passage 42 Shelter Bay, WA
Hi Terri, check out the link below...

It takes you to the P42 Knowledge Base article I wrote about the blocked vent line that I cleared. Just another alternative to consider. That was five years and the system has been trouble free ever since. Terry http://kb.sailboatowners.com/brand?post=376
 
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
Back flush it!

Since the hose and fittings are OK why not just take a hose to the vent from the outside? Squirting water back into the tank from the hull side. I do this once a season and it has kept the vent clear so far.
 
Dec 3, 2003
544
None None Rochester, NY
Pulling new hose hint

I just replaced the water heater hoses between the engine and the water heater. I bought a double-male barbed fitting the same size as the two hoses. As Peggy said, I "spliced" the new hose to the old, but used electrical tape to help secure the fitting. There was a 90 degree bend that I had to get by, and when trying to pull/push, the hose wouldn't go. I pulled it back out, re-taped the joint, and this time rubbed a few drops of dish washing soap on the fitting. The hose pulled through easily with a little lubrication. On the subject of the vent hose; I had a terrible time with mine plugging up this year. As Peggy said, if the pump gets difficult to use, and if you get a lot of air bubbles back into the bowl after pumping, you have a blocked hose. My blocked hose turned out to be a drooping vent hose after leaving the tank and before going up to the thru-hull. I imagine water somehow entered the hose and essentially blocked the hose by settling in the low spot. I cured this by adding a hose hanger, bought at Home Depot, to keep the low line parallel. This seemed to fix the problem. I know this because when you flush the head, the odor from inside the tank now wafts by you like a stinky cloud when you are in the cockpit.
 
Dec 2, 1997
8,958
- - LIttle Rock
Odor problem can be solved

What are you using in the tank, and how often are you adding it? Btw...you could have saved the price of the hose hanger, if you'd simply cut off the excess vent hose to eliminate the sag in it....'cuz you want the shortest straightest vent line possible.
 
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