Black tank flush usage and winterization

[Fishhawk]

Hi Everybody,
I searched to see if this is posted since there’s dozens of winterization and black tank flush threads however didn’t find any info on the problem I’m having

I have a 2019 Whitehawk 26rks with a black tank flush inlet. I’ve used the flush once, with really no success. When I hooked it up to the hose, only a slight trickle of water was going through the tank as indicated by the clear hose attachment.

At the time I didn’t think much of it since it’s the first time I’ve ever used one and didn’t t know any different.
Now I’m starting to wonder if there’s a problem.

While winterizing I was trying to come up with ideas on how to get antifreeze down the black tank flush line. Also, figured it can’t hurt to blow air to push any water forward into the black tank. This is where I think there might be a problem.
It seems I might have a reversed check valve. When air goes in, I hear a valve shut and no air is allowed in. This seems polar opposite of what the one way valve seems to do.

So I carefully tested if air can come out (don’t ask) and the answer is yes, air freely exits the flush nozzle but not in.

Is this expected? Perhaps this explains why the flush didn’t really produce water flow and it didn’t flush at all.

Thanks in advance for any advice

Dan

[THE MEEKER]

I use a sump pump inside a 5 gallon bucket and pump the RV antifreeze into the black tank flush.

I also do not get a high volume of water using the black tank flush. I really never investigated the possibility of a reversed check valve. I use the manual flush wand to flush out the tank monthly as it does a great job.

[Camper_bob]

Sure sounds like a backwards valve to me.

If you're going to be in there anyway, may as well replace that with a brass check valve, or something better than what's in there. Those valves are well known failure points.

[hbravo]

When I use my black flush I only get a small amount of water flow out of my waste hose. I attribute it to the flow rate of the hose vs the 30 gallon black tank. Even if you put an unrestricted hose in your toilet you won’t get a high flow rate out of the waste. That is one of the reasons you don’t dump until your black tank is full of water.

I purchased a small hand pump at CW a while back to push antifreeze into the black flush inlet. My anti-syphon valve is clear and visible in a cabinet so I can see when it is full. It doesn’t take much.

[Fishhawk]

Thanks for the feedback! I’ll let it go for now and next time it’s in for service, will make a point to have that inspected.

Cheers!

[DonaandDon]

If during that flushing operation you seen a "small flow", I would rule out the check valve as a problem. I would trace the back side of the flush station for a possible hose kink. I can clean out the cargo area and unscrew the barrier wall to gain access.

With my flush station the only way to put anything into it (besides water) is to load a hose. Whether it is a sanitation, antifreeze, cleaning product, or rinsing agent. Use a separate 100' hose load it and inject it.

Good Luck..

[wfo1955]

Greetings, i have a 2010 greyhawk 31fk. I have a low point drain for fresh water tank but cannot find any low point valves for the regular water lines. Looked under bed cabinets under sinks under chassis. Do i have any and where are they? Appreciate any help.

[Route 66 Traveler]

Thy should be where your plumbing is farthest away from your water tank. Mine happens to be under the bathroom sink, way in the back of the cabinet...had to use a flashlight to see them. One is blue, the other is red. Happy hunting.

[wfo1955]

Thank you ill look again.

[norty1]

Look underneath for the 2- 1/2 inch PEX hoses sticking out and down. The valves should be somewhere protected form the weather.