Vented Loop

[Richard]

My Hunter 37 has a vented loop in the forward hanging locker, for my head system. I also have a vent line in my holding tank. I see no reason not to get rid of the vented loop and get the smell out of the hanging locker. I am looking for other opinions.

 

[Peggie Hall/Head Mistress]

Keep the vented loop, replace the check valve

The vented loop prevents waste from the tank from backing up into the toilet when you're heeled enough to send it back into the toilet discharge line. There should be an air valve in the nipple at the top of the loop that only allows air IN, nothing out (which, btw, also eliminates the need to vent the loop to the outside of the boat). Yours apparently is either missing, needs cleaning, or needs replacing. When the loop is working the way it's supposed to, there should be no odor from it. Or, the loop may not be the culprit...it could be hose that's become permeated with odor.

 

[Jim Legere]

Which Loop?

Is the vented loop in your port locker on the discharge of a diaphragm pump under the port side of the V-berth? If so, it is to prevent backsiphoning to the holding tank through the overboard discharge line (not the pumpout connection on deck) If you only open the seacock to pump the holding tank overboard (ten miles out, or whatever) and then close it after emptying the tank, why do you need a vented loop? I am thinking of removing mine , as it serves no useful purpose other than to perfume the clothes! Incidently, I have another vented loop on the discharge from the Y valve to overboard, but this one I regard as essential. The holding tank doesn't have a loop, but is blocked by the Y valve on mine, which is shut in that direction (and open to overboard discharge). A good vented loop to have is on the intake water to the head (check archives for Ed Schenk's article on this). Our head has flooded a couple of times when visitors forget to put the lever back to DRY BOWL!

 

[Peggie Hall/Headmistress]

Note where he is, Jim...

Unless the boat came from coastal waters, it's unlikely that the tank is plumbed to dump it overboard. As for the answer to your question: "If you only open the seacock to pump the holding tank overboard (ten miles out, or whatever) and then close it after emptying the tank, why do you need a vented loop?" For the same reason you reccommend putting one on the head intake (and because the boat couldn't pass an insurance survey without it).

 

[Jim Legere]

Point taken

Point taken, Peggy. Jim