Hi Nancy, Dave and Jim,
While we recommend positioning the valves as upright or over the pipe, as opposed to beside or under the piping, it can be placed anywhere above the 3 and 9 O'clock position. We have installed our complete system on many Heartland owners coaches which includes the valves, but we usually remove ALL the plumbing from the tanks outward. We do this because Heartland still plumbs the Gray waster using 1.5" pipe making your time dumping much longer as well as being ineffective in removing all the scum, food particles, oil, soap, shampoo etc.. By simply using 3" pipe after the water exits the tank, it creates a vortex or whirlpool effect in the water draining in the tank, pulling the scum out of the tank instead of leaving it on the sidewalls and bottom. In addition it flushes out the 3" sewer hose.
If any of you are interested in knowing more about our products and services please go to our web site Drain Master .com. or contact our team at 877 787 8833 Toll free. We have lots of photos of Heartland installs and are happy to share them with you.
You can also contact me personally Doug Swarts 831 801 4827 with questions.