Does anyone have a 'fix' for the backflow of bilge water after the pump stops and the line drains back? Although the previous owner installed a checkvalve, I recently discovered the pump running my house batteries dead pushing against a line/valve blockage and don't want to repeat that again. Has anyone ever 'tee'd' off a line for a bucket-catch of the residual, rather than a valve? Are there backflow preventers that are not as prone to blockage?
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Dave Mauney
Two Pumps
Dale Don Casey in one of his books, I can find it if you like, describes a two bilge pump system. This is what I did on my O'Day 35. I put a large pump, 3500 gph, on a raised platform about 6" off the bilge bottom that has 1 1/2" line running aft. I have a second small pump, 500 gph, mounted to the bilge floor that pumps through a 1/2" line, on the short side, out near the starboard topsides at the top. This small line size minimizes the amount of water returning back to the bilge. This system works well. I can give you more details if you want. Good Winds Dave s/v DAMWEGAS
Dale Don Casey in one of his books, I can find it if you like, describes a two bilge pump system. This is what I did on my O'Day 35. I put a large pump, 3500 gph, on a raised platform about 6" off the bilge bottom that has 1 1/2" line running aft. I have a second small pump, 500 gph, mounted to the bilge floor that pumps through a 1/2" line, on the short side, out near the starboard topsides at the top. This small line size minimizes the amount of water returning back to the bilge. This system works well. I can give you more details if you want. Good Winds Dave s/v DAMWEGAS
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Chuck
I also added a check valve on the small pump
this was placed about a foot away from the pump. The valve is sitting over a stringer upside down. That way any forgien objects will fall away from the valve.
this was placed about a foot away from the pump. The valve is sitting over a stringer upside down. That way any forgien objects will fall away from the valve.
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Ed
Upside down won't work.
A check valve installed upside-down will allow water to flow back to the sump when the pump shuts off. I know this because the previous owner installed one upside-down and the sump would fill back up when the pump stopped. I turned the check valve right-side up and now no water comes back to the sump. ~ Happy sails to you ~ _/) ~
A check valve installed upside-down will allow water to flow back to the sump when the pump shuts off. I know this because the previous owner installed one upside-down and the sump would fill back up when the pump stopped. I turned the check valve right-side up and now no water comes back to the sump. ~ Happy sails to you ~ _/) ~
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David
Check
valves in the bilge pump hose are written up as an exception in any good surveyor's report. I would remove it right away.
valves in the bilge pump hose are written up as an exception in any good surveyor's report. I would remove it right away.
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Ed
I wouldn't remove a check valve.
Without it, most of the water pumped will come back to the bulge when the pump stops. Then the float goes up again, and the pump comes on again, only to repeat the process several times. With the check valve, whatever would have come back to the bilge is trapped by the valve. The next time the pump comes on, that trapped water get pumped first along with the bilge water which now takes its place. Moreover, having a check valve that connects to a hose that exits above the water-line doesn't pose any greater risk than that same hose without a check valve. So that the pump doesn't pump water back into the bilge, make sure the valve is clamped properly on both sides. ~ Happy sails to you ~ _/) ~
Without it, most of the water pumped will come back to the bulge when the pump stops. Then the float goes up again, and the pump comes on again, only to repeat the process several times. With the check valve, whatever would have come back to the bilge is trapped by the valve. The next time the pump comes on, that trapped water get pumped first along with the bilge water which now takes its place. Moreover, having a check valve that connects to a hose that exits above the water-line doesn't pose any greater risk than that same hose without a check valve. So that the pump doesn't pump water back into the bilge, make sure the valve is clamped properly on both sides. ~ Happy sails to you ~ _/) ~
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David
Ed
the float switch should always be placed slightly higher than the pump intake to prevent the condition you mentioned. Even the sensor pumps are designed so that hose water will not activate the pump. The problem with check valves in bilge hose is that when there is a failure, such as a blocked valve, it can become catastrophic.
the float switch should always be placed slightly higher than the pump intake to prevent the condition you mentioned. Even the sensor pumps are designed so that hose water will not activate the pump. The problem with check valves in bilge hose is that when there is a failure, such as a blocked valve, it can become catastrophic.
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Ed
I've worked on check valves.
Back in the Navy I used to check them according to the PMS (Preventive Maintenance Schedule). For the six years I was a Machinest Mate, I never once had to replace a single one. In my opinion, when properly installed - they're nearly 'bullet-proof'. If anything causes them to bind, it's usually when they are in the "open position". Like I said earlier, I wouldn't have a bilge pump routed to the hull without one. BTW, having the float set higher than the pump only causes the water level to be higher before the pump comes on and goes off. That's not good either. :^( ~ Happy sails to you ~ _/) ~
Back in the Navy I used to check them according to the PMS (Preventive Maintenance Schedule). For the six years I was a Machinest Mate, I never once had to replace a single one. In my opinion, when properly installed - they're nearly 'bullet-proof'. If anything causes them to bind, it's usually when they are in the "open position". Like I said earlier, I wouldn't have a bilge pump routed to the hull without one. BTW, having the float set higher than the pump only causes the water level to be higher before the pump comes on and goes off. That's not good either. :^( ~ Happy sails to you ~ _/) ~
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Gord May
Bilge Pumps & Check Valves
don't mix. 1. Most small Bilge Pumps don't develope enough pressure to RELIABLY & CONSISTENTLY open Check Valves. 2. Boat Check Valves ALWAYS fail eventually - usually due to debris from bilge. These are not industrial fittings, operating in clean fluid. 3. NEVER install a check valve (for convenience) in an (essential) Bilge Pump discharge. All system design involves trade-offs; but this is a poor value choice. OMO Gord
don't mix. 1. Most small Bilge Pumps don't develope enough pressure to RELIABLY & CONSISTENTLY open Check Valves. 2. Boat Check Valves ALWAYS fail eventually - usually due to debris from bilge. These are not industrial fittings, operating in clean fluid. 3. NEVER install a check valve (for convenience) in an (essential) Bilge Pump discharge. All system design involves trade-offs; but this is a poor value choice. OMO Gord
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Ed
I Don't agree.
The check valve on my bilge line is oversized for the line (all bronze too). My bilge pump has no problem pushing water past it, and the pump strainer will not pick up anything large enough to cause the valve to get stuck in the closed position. Bottom line, properly installed check valves work just fine. I prefer a bilge line with one than without. ~ Happy sails to you ~ _/) ~
The check valve on my bilge line is oversized for the line (all bronze too). My bilge pump has no problem pushing water past it, and the pump strainer will not pick up anything large enough to cause the valve to get stuck in the closed position. Bottom line, properly installed check valves work just fine. I prefer a bilge line with one than without. ~ Happy sails to you ~ _/) ~
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Steve O.
FWIW
I installed a check valve on my bilge pump hose and it failed the first time the pump came on. I found out that's why you don't install check valves on bilge pumps. Luckily I was there when it failed so it didn't sink my boat. I learned my lesson.
I installed a check valve on my bilge pump hose and it failed the first time the pump came on. I found out that's why you don't install check valves on bilge pumps. Luckily I was there when it failed so it didn't sink my boat. I learned my lesson.
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Ed
You used the wrong check valve.
A good one, installed properly, won't fail. ~ Happy sails to you ~ _/) ~
A good one, installed properly, won't fail. ~ Happy sails to you ~ _/) ~
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David
Check
ABYC 22.8.7.2 " a vented loop or other means to prevent siphoning into the boat. A check valve shall not be used for this purpose."
ABYC 22.8.7.2 " a vented loop or other means to prevent siphoning into the boat. A check valve shall not be used for this purpose."
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Ed
Don't care.
The check valve is there to keep water that didn't make it overboard from getting back to the bilge. My valves work great, so the ABYC rule about them does not matter to me. You do whatever makes you happy. I'll keep my check valves. ~ happy sails to you ~ _/) ~
The check valve is there to keep water that didn't make it overboard from getting back to the bilge. My valves work great, so the ABYC rule about them does not matter to me. You do whatever makes you happy. I'll keep my check valves. ~ happy sails to you ~ _/) ~
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Dale I
Stuck valve... Cont.
My mistake while rewiring the entire boat was to only verify that the pump motor 'ran' without moving any water... The last time this particular pump moved any bilge water was in 1998 before the boat hit the hard for five years... I expect that the blockage I experienced was the result of sediment etc. drying out in the line during that period from inactivity... However, I'll take this all under advisement and really appreciate the input. I'm curious though how you'd include a vented loop close enough to the pump, (on most boats), and still be effective in eliminating the flow-back. (The discharge is well above the waterline.)
My mistake while rewiring the entire boat was to only verify that the pump motor 'ran' without moving any water... The last time this particular pump moved any bilge water was in 1998 before the boat hit the hard for five years... I expect that the blockage I experienced was the result of sediment etc. drying out in the line during that period from inactivity... However, I'll take this all under advisement and really appreciate the input. I'm curious though how you'd include a vented loop close enough to the pump, (on most boats), and still be effective in eliminating the flow-back. (The discharge is well above the waterline.)
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Skip
Vented loop v. check valve
Vented loops are install solely to prevent water from siphoning into the boat when the output is below the waterline. This can apply to even a high bilge output when heeled over or when partially sunk, but not sinking yet. They will not prevent drainback into the bilge. As for drainback, I don't see the problem. I just let the water drain back into the bilge; on my boat at least it's not very much water. Keep in mind, that water is "on board" either way, so sitting in the bilge or in the bilge hose doesn't matter to me. Even if the check valve is of minimal risk, it's of minimal benefit as well, IMO. If you're using the check valve as a replacement for a vented loop, that's where you're really adding risk. The check valve to prevent drain back will tend to fail safely, ie fail with the valve open. If you're depending on it to prevent siphoning, when it fails by sticking open, the boat is probably headed to see Davy Jones.
Vented loops are install solely to prevent water from siphoning into the boat when the output is below the waterline. This can apply to even a high bilge output when heeled over or when partially sunk, but not sinking yet. They will not prevent drainback into the bilge. As for drainback, I don't see the problem. I just let the water drain back into the bilge; on my boat at least it's not very much water. Keep in mind, that water is "on board" either way, so sitting in the bilge or in the bilge hose doesn't matter to me. Even if the check valve is of minimal risk, it's of minimal benefit as well, IMO. If you're using the check valve as a replacement for a vented loop, that's where you're really adding risk. The check valve to prevent drain back will tend to fail safely, ie fail with the valve open. If you're depending on it to prevent siphoning, when it fails by sticking open, the boat is probably headed to see Davy Jones.
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Ed
My boat has both.
However, without the check valve, as the hose is rather long, too much water comes back to the bilge. The pump will cycle several times before enough water is removed for the float to not come on. With the check valve, the water does not come back to the bilge, and the next cycle pushes the water trapped by the valve overboard, as well as some of the water in the bilge. My pump does not come on as often, and the bilge stays drier longer. The fact that there is water in the hose does not bother me, as it would have been in the bilge without the check valve. ~ Happy sails to you ~ _/) ~
However, without the check valve, as the hose is rather long, too much water comes back to the bilge. The pump will cycle several times before enough water is removed for the float to not come on. With the check valve, the water does not come back to the bilge, and the next cycle pushes the water trapped by the valve overboard, as well as some of the water in the bilge. My pump does not come on as often, and the bilge stays drier longer. The fact that there is water in the hose does not bother me, as it would have been in the bilge without the check valve. ~ Happy sails to you ~ _/) ~
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Gord May
Ed?
I disagree /w Ed, who says a good check valve, properly installed is safe & reliable. Gentlemen can disagree. HOWEVER Ed: can you recommend a 'good' check valve? Gord
I disagree /w Ed, who says a good check valve, properly installed is safe & reliable. Gentlemen can disagree. HOWEVER Ed: can you recommend a 'good' check valve? Gord
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David
Check V
I think one reason insurance companys require surveys has been exhibited here by some owners who Don't Care!
I think one reason insurance companys require surveys has been exhibited here by some owners who Don't Care!
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Ed
I had mine surveyed.
He also thought the check valves were OK. My insurance didn't say anything to me about them either. I guess, as long as they're properly installed, they don't care. ~ Happy sails to you ~ _/) ~
He also thought the check valves were OK. My insurance didn't say anything to me about them either. I guess, as long as they're properly installed, they don't care. ~ Happy sails to you ~ _/) ~
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