As for check valves they are the only way to prevent back flow. Yes they can clog, yes they can minimize pump flow. I think the best option is to have 2 pumps:
-a low flow, positive displacement pump, with a small-ish suction hose and suction check valve installed as close to the raw end of the hose and mounted as low a possible in lowest part of the bilge. It needs its own discharge hose as well. This pump acts as the normal bilge pump and cleans up the back flow from the high flow pump. It also handles the incidental accumulation of water. This pump will suck the bilge dry and then push air out through the discharge hoses. A suction check valve may not even be needed. -at least one high volume pump (likely centrifugal) with large wires, large suction hose, large discharge hose, and a large machine cloth suction strainer box with no check valve. Mount the suction and pump high-ish. Mount the level switch slightly above the suction so that the pump turns off without drawings air. This acts as an emergency pump for bulk removal of water. I've had bad experiences with "duck" style check valves. They create too much head loss and don't seal against the few inches of water back pressure. They work fine in systems where considerable back pressure is present. Josh Muckley S/V Sea Hawk 1989 C&C 37+ Solomons, MD On Wed, Jul 25, 2018, 4:07 PM Bruce Pope via CnC-List <cnc-list@cnc-list.com> wrote: > After reading your post I decided to forgo check valves on both primary > and secondary bilge pumps and had the same experience with recycling bilge > water. Installed Whale Gusher check valves this spring and they both > leak. It takes about 30 minutes for leakage to top the electronic float > and cycle up pump. > > Anyone have recommendations for alternatives? > > Not a lot of reviews of check valves or non return valves. > > > Bruce > > S/V Gyrfalcon > > C&C 29-2 > > Kootenay Lake, BC > > > ------------------------------ > *From:* Randy Stafford <randal.staff...@icloud.com> > *Sent:* Wednesday, July 25, 2018 9:26 AM > *To:* cnc-list > > *Subject:* Re: Stus-List I am so done with bilge pumps... > I’ve had mixed experience with Rule pumps in three years on Grenadine. > She came with an old Rule-Mate 1100 that still works as intended. Before > the 2017 season I added a second Rule-Mate 1100 under the mast step, and it > came from the store with an inoperative internal water sensor, so automatic > mode was useless, and reversed internal wiring or impeller so that it just > churned the bilge water instead of pumping it out the discharge hose. And > yes, I’m certain I wired it correctly - this past offseason I unstepped the > mast and put in a replacement new Rule Mate 1100 which works as intended on > the exact same wiring - which I’d completely replaced before the 2017 > season with right-sized / oversized wire. There are a lot of negative > reviews of these Rule-Mate pumps on westmarine.com (one of them mine, the > most-liked negative review there). > > On a related topic, when I overhauled the bilge plumbing before the 2017 > season, I chose not to install check valves in the discharge hoses because > I was pretty influenced by http://www.yachtsurvey.com/bilge_pumps.htm. I > wrote a long post to the list about my thought process - > http://cnc-list.com/pipermail/cnc-list_cnc-list.com/2017-March/091421.html. > Turns out I drained my batteries twice last season from a cycling bilge > pump, because I didn’t manually pump the bilge often enough. And that > sucked - I had to pull the batteries out, bring them home, put them on a > charger, take them back and put them in, etc. Fortunately I didn’t kill > the battery life with those mistakes - they’ve been working fine. Pain is > a great teacher, so this past offseason I relaxed my principles and > installed Whale Gusher check valves in the discharge hoses. > > Now I’m worried that the little rubber joker valves inside those check > valves will fail and lead to pump cycling again. The big rubber joker > valve in my Jabsco head only lasts about a year, I’ve found, after which it > leaks and allows backflow. > > Cheers, > Randy Stafford > S/V Grenadine > C&C 30-1 #7 > Ken Caryl, CO > > > _______________________________________________ > > Thanks everyone for supporting this list with your contributions. Each > and every one is greatly appreciated. If you want to support the list - > use PayPal to send contribution -- https://www.paypal.me/stumurray > >
_______________________________________________ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray
