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ColoradoBnd · 08-02-2020, 12:37 PM

My black tank flush nozzle is plugged solid. I’ve been looking to find the location of the flush nozzle and some mention removing a panel, but I can’t find removable panels in my RV. I did remove several speakers from my outdoor TV compartment and see two tanks separated by not too much distance (6” or so) and a pex feed going into the top of one of those tanks. I don’t know how long that nozzle is, but it’s going to have to be short to come out between those tanks. Coach is in the signature.

alank · 08-02-2020, 02:13 PM

I don't think black tank flush nozzles would normally plug up, although they could. I think the backflow valve would be my first suspect if the system won't take water.

ColoradoBnd · 08-02-2020, 05:06 PM

That’s a good suggestion. There are lots of folks on here that complain about the nozzle plugging. That’s why I was headed in that direction.

ColoradoBnd · 08-07-2020, 04:51 PM

Well, I found the black tank flush nozzle. Removed it, cleaned it, and drilled the holes a little bigger. To be honest it wasn't that bad. I ordered a plastic and brass back flow valve. I put in the new plastic because the brass one isn't here yet. When I turned on the water that valve leaked from the bonnet, so I put the old valve back in (seems to move fine). The flush nozzle is back in place for the silicone to set. Im a little frustrated that after all that ****** work that I didn't find a "smoking gun". I cannot imagine the line is plugged because it was extraordinarily clean. Any thoughts on this? The back flow valve is the only backflow protection, right?

96 Wideglide · 08-07-2020, 05:00 PM

These Vacuum breaker valves need something like 40-45psi to open and allow water flow. when you open the water spigot, do it fast, or you may get a leak.

osuallen · 08-07-2020, 05:17 PM

Quote:

Originally Posted by 96 Wideglide

These Vacuum breaker valves need something like 40-45psi to open and allow water flow. when you open the water spigot, do it fast, or you may get a leak.

Vacuum breaker valves do not require anywhere near that kind of pressure to open. If they did, they would be completely worthless because a huge percentage of the municipalities do not provide that or much over that to a fair portion of their customers.

A Watts 1/2" VB has about 1 PSI loss at 5 gallons/minute.

96 Wideglide · 08-07-2020, 07:26 PM

Quote:

Originally Posted by osuallen

A Watts 1/2" VB has about 1 PSI loss at 5 gallons/minute.

Loss to where? Inside your vanity cabinet?

osuallen · 08-07-2020, 08:49 PM

Pressure loss through through the VB. So if you have 39 PSI at the inlet, you will have 38 at the outlet if flowing 5 GPM, which is about the maximum would would be able to flow through the flush system.

ColoradoBnd · 09-28-2020, 06:04 PM

Omg. I found the problem today after flushing with air backwards. About a year ago I changed the water inlet fitting. While blowing backwards today, I found the failed parts that were preventing forward flow. 🤬. There was a spring check valve in the inlet fitting that failed. Omg! Check that if you have a problem with this.