Black Tank Flush

Okay this is all really great stuff, thanks!

beaubeau wrote:
How does one get compressed air in there? (We live in Florida and use ours year-round -- no winterizing required).

You get one of these. You can get them from almost any hardware store, Lowes, Home Depot, TSC (Tractor Supply Company), Wall Mart may even have them:

Click here

After you screw this onto the place you'd normally attach the garden hose, you add air, just like blowing up a tire, and it forces any water out under pressure.

The only problem is, if the line is truly plugged at the anti-syphon, or even the jets in the tank, too much pressure and you could blow the lines. I do not advise using an air compressor for this, if you are clogged. If water pressure will not break it free, air pressure, could potentially be 120 psi... will blow your lines apart. If it were not clogged, there would be no problem doing this. This is how I winterize that line, by blowing air through it.

I had a similar problem on Outback about a year ago. No water spraying in the black tank. I do know what caused the problem. It was the anti-siphon vacuum breaker. I attached the garden hose to the trailer and turn it on. I didn't run some water through the hose first to clean out anything that might have crawled up the hose while it sat on the ground. Well ... gunk clogged up the anti-siphon "thing." I tried everything to free it up. You know.... you CANNOT blow backwards into those things! :h

I replaced it (yea, as I recall it was over $60 for that thing), and I've not had any problems since. Now, I always run some water through the hose before attaching.

How does one get compressed air in there? (We live in Florida and use ours year-round -- no winterizing required).

Before you start wrenching on it....try using a blast of compressed air...like when you blow out the lines for winterizing.

Common problem in the Tiffins. On my Bus I had to remove the panel directly opposite the wet bay access on the passenger side of the unit. On my 2008 Bus it required 2 screws to be removed that go up into the floor from underneath. One at each end of the panel. The skin panel can then be pulled out from the bottom and swung up. I used a stick to hold it horizontal although if you raise it further it can be totally removed. The spray nozzle is in the top of the black tank held in with 3 or 4 screws and sealed with plumber's putty. Unscrew the screws, and the nozzle will pull out. I just cleaned mine with a toothpick. Re-knead the plumbers putty and use it to re-seal the nozzle. Less than an hour's job even if you dog it.

on my '08 Allegro Bay it turned out to be the vacuum breaker, which was located in a small access panel behind the shower.
I cut the clamps took it apart, found the seal was "glued" shut, so after gently working it, it came apart. I put a very small amount of "goose" grease and put it all back together with worm clamps.
It hasn't failed me yet.

2 components that could be issue

1) Least likely....anti-siphon vacuum breaker (usually located under bath sink). They can fail to allow water to flow thru BUT typically when they fail the leak badly inside RV

2) Spray nozzle in tank. Holes get clogged from hard water (calcium etc) or from 'stuff' in tank sloshing up onto nozzle

As suggested.......leaving water connected MAY soften crud and allow flow.....BUT be CAUTIOUS

Something dried out and hardened in the spray nozzle or the check valve prior to the spray nozzle. Just leaving the water connected and pressure on the flusher may soften any matter that has hardened, but don't do that and not be there when it starts to flow. You may end up with black water coming out your roof vent if it fills before you know it is happening.

It is plugged. You will have to take it apart, some folks re-drill the holes a bit larger to stop things from plugging up. Look at the Tiffin forum for a further explanation.