Solenoid valves in head discharge

Feb 2, 2020
3
Sabre 34 MK1 Casco Bay
Folks

I am modifying my waste system this Spring in order removal the miles of unnecessary hose that runs from the head to tank back to the seacock. The 1985 factory installation used two manual valves to direct waste to either the tank, pump out or seacock. When I installed an electric head a few years ago I envisioned steam lining this system to minimize the amount of hose. I am thinking of installing two new ports on top of my tank: an 1.5 inch dip tube directly to the pump out and a 1 inch fill tube from the head. The hose from the head would include two 12v solenoid valves that would direct waste to the tank when no power is switched on: one value closed that would direct waste to the seacock, the other open to the tank via a "T". When offshore the option to discharge directly to the seacock whould be activated via a single switch that powers both valves. Can I assume I still need a vented loop between the offshore "valve" and the seacock? I don't mind installing it but was just wondering since the 12v valve will be closed and seacock shut during sailing inshore. Thanks
 
Jan 11, 2014
11,323
Sabre 362 113 Fair Haven, NY
The line from the seacock to the valve needs to have a vented loop. If not, when the valve is open seawater can back siphon into the head.

The discharge line from the head to the tank or seacock should probably be 1.5" to reduce the chance of clogging.

Why not just use a simple Y valve to direct the flow? There is no reason that solenoid valves won't work, however, that is just one more thing to go awry. With the Y valve there is only 1 valve not 2, while it is a manual valve, there is no guessing if it is functioning or not. The solenoids will require 2 switches and extra wiring. More things to fail.

The link below shows how I handled the Sabre hose mess on my S30 a few years ago. And, if you haven't read Peggy's book yet, you should get a copy.

 
Feb 2, 2020
3
Sabre 34 MK1 Casco Bay
Dave,

The discharge hose from the head is 1" (post macerator) and works fine as is. I plumbed a fresh water rinse to the system to keep odors and build up minimized. I should have mentioned that I am using a "Y" or "T" between the two valves. Since the valves in the "no power" state will be directing waste to the tank I am not stuck sending waste overboard should they fail. The two valves can be wired to a single switch to work in tandem. The current system has a lot of 1.5 inch hose running through two manual valves to a return to the seacock and deck pump out. It just seems overkill and I have never pumped my tank out through the seacock. The new dip tube for pumpout will remain 1.5 inch.

You are right a vented loop is a good idea. I currently do not have one on my 3/4 salt water intake hose going the head. It has not been a problem but should be installed. I guess my aim into simplify the system to minimize the amount of hose. I am a fan of Peggy and her guidance is top notch. I wonder if she has a solenoid recommendation... Thanks Dave. I will check out your install.
 
Dec 2, 1997
8,709
- - LIttle Rock
Tru-Design has electric y-valves: Electronic Aquavalve (Y Valve) (Tru Design Valf Product)
All of Raritan's fittings and manual valves are supplied by Tru-Design, which is an excellent indication of the quality of their products.

You are right a vented loop is a good idea. I currently do not have one on my 3/4 salt water intake hose going the head.
The intake line from the thru-hull to the pump is the wrong place for a vented loop...it belongs between the pump the bowl, which requires replacing the short piece of hose the toilet mfrs use to connect 'em with hoses long to put the loop where it needs to be: 6-8" above waterline at any angle of heel...which on most sailboats puts it 2-3' above the bowl.

6' is about as far as most manual or electric toilets can push bowl contents...If your tank is much more than 6' from the toilet, flushes won't make it to the tank without a lot of help from gravity unless your toilet is one of the high end all china "thrones." You might want to consider finding another location for the tank that's closer to the toilet.

You said several things in you post that make me a little nervous about your planned replumbing project... that maybe you and I should prob'ly chat one-on-one about it before you buy anything. Send me a PM if you'd like to do that.

--Peggie
 
Feb 2, 2020
3
Sabre 34 MK1 Casco Bay
Peggie,

Thanks for the response. For sure the vented loop will be post pump on the intake. I have lived with out it for some time but planning on installing one now. My head is only about 4 feet from the tank. I installed the electric head about 5 years ago and its worked great. One of the problems I face is gaining hight for the loop due to the interior built out configuration. I will send you a PM for sure. Look forward to your input.