Black water tank flushing question

[livinthelife]

When flushing the black water tank the flushing sprayer only works about 1/3 of the time. My husband believes it's due to not high enough water pressure at some of the RV parks we've stayed at. Does that sound right?

Possibly our vacuum breaker requires a higher pressure to let the water flow. But we don't know for sure where the vacuum breaker is on our 26RL. We think it's behind the shower, but don't know where the access panel is.

[gr8daggett]

I have replaced my Vaccum Breaker (plastic) with a brass version by Watts. In my 2015 337RLS it is behind the shower controls. I just remove the panel in my closet behind the shower. I use a pressure regulator when I flush mine.

[livinthelife]

I have replaced my Vaccum Breaker (plastic) with a brass version by Watts. In my 2015 337RLS it is behind the shower controls. I just remove the panel in my closet behind the shower. I use a pressure regulator when I flush mine.

Thanks, but we don't have a closet behind the shower. It backs up to the hutch in the kitchen.

When we use the pressure regulator the flushing spray won't work. It seems to take more than 40psi to flush.

[carnolddsm]

Thanks, but we don't have a closet behind the shower. It backs up to the hutch in the kitchen.

When we use the pressure regulator the flushing spray won't work. It seems to take more than 40psi to flush.

As Grand Design uses many of the same building techniques across all product lines, take a close look at the panel(s) at the back of the hutch. You may find a panel held in place with screws painted to closely match the color of the panel.

While I use a pressure regulator on the fresh water line I don’t use one for the black tank flush. The engineers on the forum may explain the error of my thinking: maximum line pressure occurs when no water is flowing, since the flush line always has flowing water while there is pressure it is not full line pressure.

[RVRunners]

As Grand Design uses many of the same building techniques across all product lines, take a close look at the panel(s) at the back of the hutch. You may find a panel held in place with screws painted to closely match the color of the panel.

While I use a pressure regulator on the fresh water line I don’t use one for the black tank flush. The engineers on the forum may explain the error of my thinking: maximum line pressure occurs when no water is flowing, since the flush line always has flowing water while there is pressure it is not full line pressure.

Exactly. I don’t use a regulator either. No problem.

[Cate&Rob]

livinthelife - Below the faucets in the shower is a panel held in place with four screws and sealed with silicone. The vacuum breaker is behind this panel. At least, it is supposed to be. Some drop down and have to be fished up through this opening to replace.

Rob

[Canyonlight]

And here is what our black tank flusher vacuum valve looked like after I removed our shower water valves/handles panel which Rob referenced in post #6:


Dan

[livinthelife]

livinthelife - Below the faucets in the shower is a panel held in place with four screws and sealed with silicone. The vacuum breaker is behind this panel. At least, it is supposed to be. Some drop down and have to be fished up through this opening to replace.

Rob

And here is what our black tank flusher vacuum valve looked like after I removed our shower water valves/handles panel which Rob referenced in post #6:


Dan

Thank you both. We never noticed that handle was in a separate panel.

[livinthelife]

livinthelife - Below the faucets in the shower is a panel held in place with four screws and sealed with silicone. The vacuum breaker is behind this panel. At least, it is supposed to be. Some drop down and have to be fished up through this opening to replace.

Rob

OK, finally had time to track this down. My husband opened the panel and, lo and behold! the hose that's attached to the vacuum breaker was bent double and stuffed into the space. The hoses were kinked in two places. He was able to straighten it out and push it back down in the void without bending them again. This should do the trick. Seems to be working much better now.