What is this part and what does it do?

[rcknrbn]

Noticed some damp folded towels in the small cabinet under the sink in the bedroom and assumed I had a leak from the p-trap or something sink related. Turns out this (pictured) device has an occasional drip. I assume it's a vacuum breaker or something similar. Is it repairable? If not, where do you purchase one? What purpose does it serve? Just something I haven't seen listed on some of the RV parts sites.

Thanks in advance.

[Me_Again]

smkettner wrote:
Does it have to be inside? Otherwise consider a pan under it and let it drip during infrequant use.

It has to be above the tank level a few feet. What they need is one that has a vent pipe that comes back down out of the trailer (roof or bottom), so if it leaks the water drops on the ground or goes on the roof and does not flood the trailer inside. They hide these in walls, under vanities, behind showers and other places.

I first time I used my tank flush, it flooded the whole trailer. Mine was behind a panel in the computer desk of all places. So I removed it and installed a shutoff valve in the wash line behind the lower side panel where the inlet is located, and bypassed the piping going up into the computer desk. Chris

[Me_Again]

srosa wrote:
I ruined one by leaving a garden hose hooked to the flush inlet on a very hot day. The end of the hose was plugged by a closed spigot and the pressure ruined the check valve. Water then backed up into the valve when flushing the tank and it leaked. The tank flush quit working too until I replaced its backflow preventer. I went with a brass one instead of plastic. Works great again with no leaks.

That makes no sense, the check valve lets water into the black tank and would not block a pressure build up unless it had already failed, and pushed the seal to the other side of the valve. The one on my hot water tank failed like that and would not let hot water out.

The OP picture shows both a check valve(white plastic piece like is used on hot water heaters), and a vacuum break(brass piece) that just lets air in the line when the hose is disconnected. Chris

[srosa]

Old-Biscuit wrote:

srosa wrote:
Leaky back flow preventers is a common problem. Universal replacement kits are available online for $20 to $30. Leaving a hose connected to the black tank flush can cause these to valves to stop working and leak.

Please explain what you mean by that statement.
I'm not understanding the situation or concern.
Thanks

The backflow preventer kits are a common repair part so they do fail from time to time. I ruined one by leaving a garden hose hooked to the flush inlet on a very hot day. The end of the hose was plugged by a closed spigot and the pressure ruined the check valve. Water then backed up into the valve when flushing the tank and it leaked. The tank flush quit working too until I replaced its backflow preventer. I went with a brass one instead of plastic. Works great again with no leaks.

[time2roll]

Does it have to be inside? Otherwise consider a pan under it and let it drip during infrequant use.

[Old-Biscuit]

srosa wrote:
Leaky back flow preventers is a common problem. Universal replacement kits are available online for $20 to $30. Leaving a hose connected to the black tank flush can cause these to valves to stop working and leak.

Please explain what you mean by that statement.
I'm not understanding the situation or concern.
Thanks

[srosa]

Leaky back flow preventers is a common problem. Universal replacement kits are available online for $20 to $30. Leaving a hose connected to the black tank flush can cause these to valves to stop working and leak.

[HappyKayakers]

dyb wrote:
is this a add on device for a after market flush kit OR does any factory installed black flush have this valve. I have a Jayco and haven,t seen this unless it is in the enclosed under belly.

It wouldn't be in the underbelly, has to be higher than the toilet drain. Mine is in the wall behind the toilet, others are behind the shower. Next time you use it, wander around inside and listen for the sound (as long as you leave the black tank valve open).

[dyb]

is this a add on device for a after market flush kit OR does any factory installed black flush have this valve. I have a Jayco and haven,t seen this unless it is in the enclosed under belly.

[fivecodys]

chipper wrote:

HappyKayakers wrote:
I have a fitting like that for my black tank flush system.

Thats what it is. A vacuum breaker to the black water tank flusher.

X2

Bill

[rcknrbn]

I just disassembled the device. Cleaned it a bit (not really cleanable). Had some gunk in the chamber where the backflow device slides up and down. Lubed it with some silicone spray. Reassembled in the upright position. Ran the black tank flush and all seems well for now. I'll report back with any updates.

Thanks for the prompt, positive input.

[skipnchar]

probably a back flow preventer.

[korbe]

The anti-syphon devise is to be located above(higher in elevation) than the incoming and outgoing lines to work properly and not to leak. Maybe it just fell over from the upright position? Maybe just needs to be straightened out and raised to stop leaking. But if you winterize, freezable water could get caught in there and freeze if not drainable on both sides.

[Old-Biscuit]

sch911 wrote:
Yes it's a vacuum breaker. And yes it's installed upside down. This has already been pointed out by others but of course many don't read before posting. Just change the orientation so the top (with the screw) is up and you're good to go.

Exactly.....

The bell shaped top is what allows air in so the water can drain after supply has been turned off.

Water is dripping out because it's upside down.
Flip it UP and secure it so it stays UP

[rcknrbn]

Well, I'll give that a shot before replacing it. Seems odd the manufacturer would have installed it that way and its been in this position for 6 years with no leaks noticed. Another person who replied added that his is in the same place.