My bilge pump (Hunter 336) cycles off and on after the first time it comes on because of then reverse water flow in the hose.My concern is that this is not good for the pump,switch and the battery. People have been advising me against putting in a check valve to stop this cycling but no one has given me a good reason why not to put in a check valve other then it is not a good idea. Can anyone tell me why ? If it is such a bad idea how do I stop the bilge pump from cycling on and off? Some times the pump will come on twenty times or more! It is driving me crazy ! The Hunter 336 has a small bilge and it is split in half, the cooler and shower both drain into the bilge on this boat. Thanks for your help!
- Status
- Not open for further replies.
D
Debra Blatnik
The answer I got on the same question
twofold: 1. Sometimes the presure from the water after the valve will keep the pump from pumping .... seems like if you had the right pump that wouldn't be an issue 2. sooner or later the check valve will stick. Then your pump will be worthless....this will happen just when you need it most, or when you are away from the boat and won't notice it. Checking in "This Old Boat" the recommendation is to install a 2nd pump lower in the bilge, smaller with a narrow hose to minimize the water that falls back. Keep your main pump and have it only operate at higher water levels. The smaller amount of water should evaporate. I am going to try this, as my main pump doesn't cycl, but it leaves a good amount of water in the bilge because it is mounted higer.
twofold: 1. Sometimes the presure from the water after the valve will keep the pump from pumping .... seems like if you had the right pump that wouldn't be an issue 2. sooner or later the check valve will stick. Then your pump will be worthless....this will happen just when you need it most, or when you are away from the boat and won't notice it. Checking in "This Old Boat" the recommendation is to install a 2nd pump lower in the bilge, smaller with a narrow hose to minimize the water that falls back. Keep your main pump and have it only operate at higher water levels. The smaller amount of water should evaporate. I am going to try this, as my main pump doesn't cycl, but it leaves a good amount of water in the bilge because it is mounted higer.
P
Peggie Hall/Head Mistress
First thing to check:
the shower and cooler draining into the bilge...install a sump. Is the water in your bilge salt or fresh? A pint or so of water draining back down the bilge pump line should not cause your bilge pump to cycle almost continuously. It should even be enough to turn the bilge pump back on. So your cooler is putting a LOT of water in the bilge, or you're taking on water. Finding out whether it's salt or fresh will tell you. If it's salt, it may be being forced up the bilge pump hose--an effect known as "ram water"--when you're underway on that tack. The solution to that problem is a one way valve in the hose...I had to install one in my own boat. I'd also install a sump for the cooler and shower...if for no other reason than, wet bilges stink. Install a sump and you'd be amazed at how much better your whole boat will smell--provided you give the bilge a real cleaning--including a thorough hosing out and drying out--as soon as you install it, and keep the sump clean.
the shower and cooler draining into the bilge...install a sump. Is the water in your bilge salt or fresh? A pint or so of water draining back down the bilge pump line should not cause your bilge pump to cycle almost continuously. It should even be enough to turn the bilge pump back on. So your cooler is putting a LOT of water in the bilge, or you're taking on water. Finding out whether it's salt or fresh will tell you. If it's salt, it may be being forced up the bilge pump hose--an effect known as "ram water"--when you're underway on that tack. The solution to that problem is a one way valve in the hose...I had to install one in my own boat. I'd also install a sump for the cooler and shower...if for no other reason than, wet bilges stink. Install a sump and you'd be amazed at how much better your whole boat will smell--provided you give the bilge a real cleaning--including a thorough hosing out and drying out--as soon as you install it, and keep the sump clean.
T
Terry Arnold
bilge float and check valves
One very good reason to keep check valves off the automatic bilge pump system is that with a check, especially one right at the pump, the self cleaning back flush action of the return water after the bilge shuts down is prevented. Thus, trash around the bilge pump screen will continue to accumulate until it is clogged. You may be able to figure the thing out by adding water to the bilge at the dock until the pump comes on, and then see if and why the repetitive pumping occurs while sitting still and upright. Could be that relocating your float switch would cure the whole thing.
One very good reason to keep check valves off the automatic bilge pump system is that with a check, especially one right at the pump, the self cleaning back flush action of the return water after the bilge shuts down is prevented. Thus, trash around the bilge pump screen will continue to accumulate until it is clogged. You may be able to figure the thing out by adding water to the bilge at the dock until the pump comes on, and then see if and why the repetitive pumping occurs while sitting still and upright. Could be that relocating your float switch would cure the whole thing.
P
Peggie Hall/Head Mistress
If there's enough trash and "glop" in the bilge
to clog the screen on a bilge pump, it's way PAST time to clean the bilge!
to clog the screen on a bilge pump, it's way PAST time to clean the bilge!
J
John
Float switch is mounted to low
If your bilge pump is cycling, your float switch is mounted to low in the bilge in relation to the suction on the pump. You can either lower the suction point or raise the float switch. A few inches either way will make a lot of difference. Several of the previous replies hit on good reasons for not using check valves in bilge pump lines. Check valves (especially small plastic ones) are famous for clogging up and/or freezing up, restricting or preventing the flow of bilge water. Remember the main reason for having a bilge pump is to prevent the boat from sinking in an emergency. I agree with Peggy about keeping the bilge clean, it's a safety issue. But it doesn't take much to plug up a small check valve and it always seems to happen at a bad time. If you hit a log and put a hole in the hull, lots of things will start floating around in the bilge, and you wouldn't have time to clean out a check valve. On the other hand if the boat is at the dock and you are not there, a plugged check valve will result in the pump running constantly and draining the battery or burning up the pump. I have two pumps on my boat. One manual pump and one automatic/electric pump. The suction on the manual pump goes all the way to the bottom of the sump in the bilge. A few strokes with the manual pump and there is less than an inch of water remaining at the bottom of the sump. The electric pump only comes on when I use the shower. I wish I had a separate sump and pump for the shower, but I don't. Hope that helps. John
If your bilge pump is cycling, your float switch is mounted to low in the bilge in relation to the suction on the pump. You can either lower the suction point or raise the float switch. A few inches either way will make a lot of difference. Several of the previous replies hit on good reasons for not using check valves in bilge pump lines. Check valves (especially small plastic ones) are famous for clogging up and/or freezing up, restricting or preventing the flow of bilge water. Remember the main reason for having a bilge pump is to prevent the boat from sinking in an emergency. I agree with Peggy about keeping the bilge clean, it's a safety issue. But it doesn't take much to plug up a small check valve and it always seems to happen at a bad time. If you hit a log and put a hole in the hull, lots of things will start floating around in the bilge, and you wouldn't have time to clean out a check valve. On the other hand if the boat is at the dock and you are not there, a plugged check valve will result in the pump running constantly and draining the battery or burning up the pump. I have two pumps on my boat. One manual pump and one automatic/electric pump. The suction on the manual pump goes all the way to the bottom of the sump in the bilge. A few strokes with the manual pump and there is less than an inch of water remaining at the bottom of the sump. The electric pump only comes on when I use the shower. I wish I had a separate sump and pump for the shower, but I don't. Hope that helps. John
P
Peggie Hall/Head Mistress
Check valve vs. one way valve...
I'm not sure we're talking about the same thing here. To relate it to my "specialty," the joker valve in a toilet is a one valve (kinda)...there's nothing in it to clog or freeze up...but over time, it can become a two-way valve. Although there's a good case for not putting any time of mechanical check valve in a bilge pump line, I see nothing wrong with a simple one way valve in a bilge pump hose...I put one on the forward bilge pump on my own boat. The bilge pump--because it has a filter to prevent anything from getting into it and freezing it up-- will clog up and quit working LONG before a one-way valve in the hose will.
I'm not sure we're talking about the same thing here. To relate it to my "specialty," the joker valve in a toilet is a one valve (kinda)...there's nothing in it to clog or freeze up...but over time, it can become a two-way valve. Although there's a good case for not putting any time of mechanical check valve in a bilge pump line, I see nothing wrong with a simple one way valve in a bilge pump hose...I put one on the forward bilge pump on my own boat. The bilge pump--because it has a filter to prevent anything from getting into it and freezing it up-- will clog up and quit working LONG before a one-way valve in the hose will.
B
Bob
Check valve or one way valve
I installed a bronze 1-way/flapper valve in my bilge hose for the same reason (cycling). Eight feet of 1-1/8 hose on an uphill run can hold quite a bit of water. My AC condensate and reefer drain into the bilge, and the bilge is also where I installed the AC raw water pick-up. I inspect the bilge at least weekly and clean everything, and have never had a problem.
I installed a bronze 1-way/flapper valve in my bilge hose for the same reason (cycling). Eight feet of 1-1/8 hose on an uphill run can hold quite a bit of water. My AC condensate and reefer drain into the bilge, and the bilge is also where I installed the AC raw water pick-up. I inspect the bilge at least weekly and clean everything, and have never had a problem.
C
Carl and Juliana Dupre
Minimal Flow Resistance.....
...is what you want in your bilge pump line. Bilge pumps are small centrifugal pumps, and the flow rate for this kind of pump drops off very quickly if you have any kind of backpressure in the pump discharge line. Traditional wisdom says that you should avoid Anything that can add backpressure and decrease the pumping rate, and that includes check valves. Do "one-way valves" such as flappers or a joker-type valve add significant backpressure? Don't know, and we're not sure we want to find out. Try looking at the pump-on / pump-off limits on your bilge pump switch; they might just be set too close. There should be about 1 to 1 1/2 inches of difference, depending upon the depth of the bilge. Carl and Jule s/v 'Syzygy'
...is what you want in your bilge pump line. Bilge pumps are small centrifugal pumps, and the flow rate for this kind of pump drops off very quickly if you have any kind of backpressure in the pump discharge line. Traditional wisdom says that you should avoid Anything that can add backpressure and decrease the pumping rate, and that includes check valves. Do "one-way valves" such as flappers or a joker-type valve add significant backpressure? Don't know, and we're not sure we want to find out. Try looking at the pump-on / pump-off limits on your bilge pump switch; they might just be set too close. There should be about 1 to 1 1/2 inches of difference, depending upon the depth of the bilge. Carl and Jule s/v 'Syzygy'
D
Dave
Volumetric Displacement
Pete, The reason the switch keeps cycling is the volume of water returning to the bilge is enough to elevate the switch to the point of activation. You can fix this as follows. Use a smaller hose so the volume backflushing will be less...this may cause reduced pump capacity for saving your boat from sinking which on your hunter 336 could be at any moment. Another option is get a different kind of switch with a longer throw. I used a Rule switch and found it wouldn't shut off so I went to the superswitch and it works fine. There are other brands as well. A third option is to modify your boat to increase the volume in the bilge. I would start by hauling the boat and removing the keel, then cut out the bilge with a chainsaw and lay up a new bilge with more volume and then replace the keel. Let me know if you need any more suggestions and I'll look forward to your hull modification project. Dave
Pete, The reason the switch keeps cycling is the volume of water returning to the bilge is enough to elevate the switch to the point of activation. You can fix this as follows. Use a smaller hose so the volume backflushing will be less...this may cause reduced pump capacity for saving your boat from sinking which on your hunter 336 could be at any moment. Another option is get a different kind of switch with a longer throw. I used a Rule switch and found it wouldn't shut off so I went to the superswitch and it works fine. There are other brands as well. A third option is to modify your boat to increase the volume in the bilge. I would start by hauling the boat and removing the keel, then cut out the bilge with a chainsaw and lay up a new bilge with more volume and then replace the keel. Let me know if you need any more suggestions and I'll look forward to your hull modification project. Dave
- Status
- Not open for further replies.