Vacuflush Not Venting

[Davidk10]

Vacuflush Venting issue

Hi All!


I have a “sort of issue” with my vacuflush system not venting. When I flush the toilet there is no positive venting pressure out of the exterior vent. To my understanding, whatever is pushed into the holding tank will displace air and it vents it outside. I’ve read everything imaginable about vacuflush issues haven’t seen this one and can’t figure out why this is happening. You would assume without proper venting the system would not function properly or at all. In my case the system works perfectly. Below is what I’ve done and tested and observed.

1. I flushed the vent hose from the hull side of the filter with water and it flowed out the vent overboard without any leaks into the interior of the bilge.
2. I flushed the tank side of the vent hose into the tank with water. It flowed freely into the tank and there were no leaks.
3. When I do a dockside pump out with the vent hoses and filter connected you can hear and feel a very strong suction from the through hull vent - no obstruction there
4. Top of holding tank where the sender goes in is sealed tight
5. The tank itself is solid with no leaks or cracks. I filled the tank completely up and didn’t observe any leaking. — assuming there was a small crack or pin hole that would not allow waste or water out would not become the defacto vent as the hose through the filter is the path of least resistance
6. Duck bills are 3 months old
7. Bellow is in good shape with no cracks
8. Bellow sump was cleaned and de-calcified
9. Bellow compartment seal is good with no visible leaks
10. System will not cycle , run or lose pressure at all. (At least for 12-16 hours when I’m around to hear it)
11. When the toilet is flushed there is no “breeze” or airflow from anywhere in the system I can put my hand in around to feel.
12. Toilet ball valve seal works , again, no air leaks as the system doesn’t cycle.

I can say that the odour in the bilge from the holding tank is worse this year than any prior. The boat is a 1999 and I assume the hoses are original. The past owner hadn’t used the head system for close to a decade. I’ve used it the past two years for all purposes so my assumption is that permeation is the culprit for that. I was also playing with different enzymes that claim to remove all odours instead of using the dometic aquamax blue enzyme with odour masking stuff.

Any insight out there for this? I’m saying it’s a sort of problem because it isn’t normal function but it’s functioning normally. I’m concerned that this is going to lead to a serious issue in the future or the system not functioning at all.

Thank You!