Using the external hose pipe for black water tank flush.

[boyscout]

Just FYI... an example of a similar part

Attachment 27163

What does the check valve do Jim?

One of GD's trusted gurus told me that the vacuum break allows water to flow away from it in both directions as soon as the input water pressure is removed.

Looks like that check valve would hold water (at least for a while) on that side of the system. How does it work?

[FreddieMac]

Just FYI... an example of a similar part

Attachment 27163

There is one of these under my bathroom sink. I know that because it leaked on the first trip because it was not properly tightened down. System leaked only when using the black water flush. There is a vacuum break on the system. This is why I removed the plans to attach my blackwater flush to my filtering system.

[JCR GD]

What does the check valve do Jim?

One of GD's trusted gurus told me that the vacuum break allows water to flow away from it in both directions as soon as the input water pressure is removed.

Looks like that check valve would hold water (at least for a while) on that side of the system. How does it work?

Recap... It does not allow any flow from black tank toward inlet. Black tank end is on horizontal connection. When water pressure applied to inlet (bottom connection) it closes vacuum break and pushes check valve open. When pressure is removed the check valve closes and the vacuum break opens.

Yes, I agree, I suppose a bit of water will stay in black tank side until it gravitates to tank via air exchange by vibration etc. unless the check valve actually lets a bit of air through to allow the water to flow out. Boils down to the "strength" of the spring on the check side.

[FreddieMac]

Recap... It does not allow any flow from black tank toward inlet. Black tank end is on horizontal connection. When water pressure applied to inlet (bottom connection) it closes vacuum break and pushes check valve open. When pressure is removed the check valve closes and the vacuum break opens.

Yes, I agree, I suppose a bit of water will stay in black tank side until it gravitates to tank via air exchange by vibration etc. unless the check valve actually lets a bit of air through to allow the water to flow out. Boils down to the "strength" of the spring on the check side.

I found the vacuum break/ check valve for the black tank flush under the sink in my bathroom. I looked up the part number and that is exactly what it does. So there is a check valve on the black tank flush which is why the owners manual says to not put another check valve on it. The vacuum break portion of this is a vent that sits on the top of the sink pipe. That valve was leaking and I found both the water lines going to it were not tightened and seated properly. I re-seated them and tightened them down and then ran the black water flush for 10 minutes without any leaks.

[John612]

Maybe I'm missing something, but I will always carry a black water hose. Say you're at a dump station that has a fresh water refill faucet and a black water rinse faucet. With only one hose you would have to connect your your fresh water hose to the station's black water faucet to rinse your black tank. That doesn't sound too good.

[chrisopy]

I carry a separate hose also just to hose other stuff off around the camper. I have a "Y" from the post and then one is my freshwater hose, and the other I leave connected to hose off whatever I may need to. I use this same one to flush the black tank. I don't see how there would be any backflow anyways unless you left the flush valve closed and it backed all the way up.

[Kevin2282]

Do anyone know where the black tank flush vacuum break is on a 28BH? I have a funny feeling it’s behind the shower valves. I would like to get a spare.

Thanks,
Kevin

[FreddieMac]

Maybe I'm missing something, but I will always carry a black water hose. Say you're at a dump station that has a fresh water refill faucet and a black water rinse faucet. With only one hose you would have to connect your your fresh water hose to the station's black water faucet to rinse your black tank. That doesn't sound too good.

No the original question was about using the provided hose for the external shower to feed the black tank flush. Not to use the white water hose on the flush.

[Csmit583]

Use a separate hose. If you contaminate your fresh water piping you will never get it clean.

[PHMadness]

We tried using the quick connect hose but we couldn't get the same results as connecting a regular hose to the black tank flush. I think there are too many small fittings with sharp 90 degree turns behind the Nautilus panel that reduce the flow too much. You could have better results though. Doesn't hurt to try, make work well for you.

I was told in my PDI to do exactly this, I did try it and found the results lackluster as well. I went back to the two hose system I always used in the past on previous units.