Why are there two waste water dump valves?

yakflyer · January 30, 2011, 07:23 PM

I have two T-valves underneath the toilet compartment for dumping. What is the difference between the two dumps?

Oz · January 30, 2011, 07:26 PM

Many newer rigs have a single dump valve. Our older rigs have two. One for the "gray" water holding tank (sink and shower water) and one for the "black" water holidng tank (commode).

OldEdBrady · January 30, 2011, 11:32 PM

A very, very few had a third valve. It was usually labeled "Mother-in-Law." W%

tomr · January 31, 2011, 07:03 AM

I think the newer rigs still have two dump valves. It's just that both are "Y'd" together so that you can easily empty both via a single hose, without having to switch the hose between two connectors...

Oz · January 31, 2011, 07:18 AM

Yes, that's what I meant, Tom. I didn't fully describe how the two tanks drain together, thank you for filling in the blank for me!

I have seen the single outlet rigs on a couple Allegros back to the 1989 model year.

tomr · January 31, 2011, 07:25 AM

...sorry if I sounded like a smarta_ss. I've always meant to fabricate some type of Y out of PVC pipe to solve this annoyance, but alas there's always something more pressing D:oH!

tiinytina · January 31, 2011, 09:21 AM

Our 1987 Allegro has 2 valves but one outlet... if you have this type of set up always open the black water valve first, when you hear the last gurgle pour 3-5gal of water down the commode to flush out the tank completely, then open the gray tank valve to completely purge outlet of black water residue....

tina

ClydesdaleKevin · January 31, 2011, 12:26 PM

Our 89 HR is the same...one big valve for black, one small valve for grey, and only one outlet.

Kev

DaveVA78Chieftain · January 31, 2011, 09:34 PM

For the shared black/grey outlet feed by seperate dump valves, CAMCO makes a addon outlet valve (attaches like the dump hose). Given the grey tank on early RV's is typically to small and fills up long before the black tank does, this addition allows you to drain the grey tank to the black tank thereby allowing you to stay longer before having to dump.

Dave

salplmb · January 31, 2011, 11:01 PM

hey guys,
just a litte thought.
some of the older parks i have been to have had a seperate drain system for the gray water so you could leave the gray water hooked up and not have to worry about having to dump the gary water tank. only had to go dump the black at the dump station. i thought this was why they had the two seperate valves for our old rigs. thought it was a good idea too. don't see it much now though.
sal