Black tank Flush Hose leaking

[Jim-Dot]

When I winterized my 2021 303RLS last fall I used my compressor around 35 psi to blow out the black tank flush hose. I then poured antifreeze in the hose. Went from Wisconsin to Texas just before Christmas. The first time I used the flush, water began leaking from above and between the water heater and furnace. The hose goes from the Nautilus panel down to the floor behind the furnace to where it starts to go up between water heater and furnace into a cavity (I think) and that seems where the water is leaking from.
Can anyone tell me why the hose goes up into the ceiling area of the water heater & furnace compartment (where I think water is coming from)?? Also, where under the floor, are the black, two gray, and fresh water tanks located?
I'm wondering if anyone has had this problem and how can it be repaired? Why is this hose going up if the black tank is down below the floor??
Thanks for your help,
Jim Nack

[ncitro]

When I winterized my 2021 303RLS last fall I used my compressor around 35 psi to blow out the black tank flush hose. I then poured antifreeze in the hose. Went from Wisconsin to Texas just before Christmas. The first time I used the flush, water began leaking from above and between the water heater and furnace. The hose goes from the Nautilus panel down to the floor behind the furnace to where it starts to go up between water heater and furnace into a cavity (I think) and that seems where the water is leaking from.
Can anyone tell me why the hose goes up into the ceiling area of the water heater & furnace compartment (where I think water is coming from)?? Also, where under the floor, are the black, two gray, and fresh water tanks located?
I'm wondering if anyone has had this problem and how can it be repaired? Why is this hose going up if the black tank is down below the floor??
Thanks for your help,
Jim Nack

There is a check valve (vacuum breaker) in the black flush line that needs to be higher than the toilet. It does occasionally drip water and can fail and leak, or the connections can fail. It is usually located behind the shower controls so you can access it.

[guest2]

When I winterized my 2021 303RLS last fall I used my compressor around 35 psi to blow out the black tank flush hose. I then poured antifreeze in the hose. Went from Wisconsin to Texas just before Christmas. The first time I used the flush, water began leaking from above and between the water heater and furnace. The hose goes from the Nautilus panel down to the floor behind the furnace to where it starts to go up between water heater and furnace into a cavity (I think) and that seems where the water is leaking from.
Can anyone tell me why the hose goes up into the ceiling area of the water heater & furnace compartment (where I think water is coming from)?? Also, where under the floor, are the black, two gray, and fresh water tanks located?
I'm wondering if anyone has had this problem and how can it be repaired? Why is this hose going up if the black tank is down below the floor??
Thanks for your help,
Jim Nack

I’ve never used more than 5psi when blowing lines.
Rich

[Cate&Rob]

There is a vacuum break (search this name on this forum for more info) located behind the shower wall. It is accessed by removing the cover plate below the shower valves. Sometimes this device is easy to reach . . . sometimes it is not. Its location over the furnace in a 303 is very “unfortunate” because when it leaks, this water lands on the control board within the furnace. (ask me how I know this ). The black tank is under the pass through on the curb (right) side. The shower grey is on the street (left) side, The galley grey tank is crosswise at about the entry door. See attached picture.

Rob

[Jim-Dot]

To all that relied especially Cate & Rob, I'm sorry for the late reply. Haven't had time to check the valve, been busy traveling and setting up at our final temporary winter RV park in South Texas. Will be here 'till the end of March and will have time for repair.
Thanks for the valve description and tank location.
Jim & Dorothy

[Jim-Dot]

The other day I tackled the problem. Removed the plate holding the shower faucets, reached in and down through the small hole with both hands and removed valve (very difficult). Ordered new valve from Amazon ($23} installed (again difficult) and finished. Problem solved!
What caused the valve to fail in the first place??
Thanks to Cate & Rob for the info.

[guest2]

The other day I tackled the problem. Removed the plate holding the shower faucets, reached in and down through the small hole with both hands and removed valve (very difficult). Ordered new valve from Amazon ($23} installed (again difficult) and finished. Problem solved!
What caused the valve to fail in the first place??
Thanks to Cate & Rob for the info.

My guess is 35psi of air pressure.
Rich