Bilge coming on more than normal

dsbentley · #1 (**permalink**) 08-13-2007

I have a rule 3700 in my aft bilge and this goes out a 1 1/2" discharge line through a check valve up about 6' in height and 15 feet in length then goes through an anti siphon before going out the threw hull fitting. I have noticed that my bilge pump has been going about every hour after I hear a gurgling sound for a few seconds in the main berth right near the anti siphon. I took the anti siphon valve apart on top and it looked like the rubber piece had gone bad so I bought a new valve. I have been told that the anti siphone should not be allowing water back into the bilge, but I cant think of any other reason that I am hearing this sound right near the anti siphon. Is it possible that my check valve is going bad and letting the water go back in the bilge after an hour?

sailingdog · #2 (**permalink**) 08-13-2007

Six feet of rise is an awful lot for a bilge pump to handle. Are you aware that the rise and the check valve will both reduce the pumping capacity of that bilge pump, and that in general, a bilge pump output line shouldn't have a check valve in it.

What may be happening is the check valve may be leaking, and after an hour or so, enough water comes down from the fifteen foot length of hose (15' x 1.5" diamter is an awful lot of water), and it causes the float valve to trigger.

IMHO, you'd be much better off running a smaller hose to a smaller bilge pump and then raising the float switch of the larger bilge pump. The smaller one would cycle for emptying the bilge, and having a smaller diameter hose, would have less water back flushing through it when the pump stops. Then you could get rid of the check valve in the larger hose, since it would only trigger when a lot more water was in the bilge.

TrueBlue · #3 (**permalink**) 08-13-2007

The gurgling sound could also be a normal sound for the check valve whenever the need for discharging water occurs. I would first look into other means of ingress from either onboard tankage water or seawater. It is possible the boat may have a leak elsewhere.

dsbentley · #4 (**permalink**) 08-13-2007

sd, I agree with what you are saying, but I question the fact that the boat has been working fine with this configuration for 20 years so something has recently changed. I know there is no other leak's as I have monitored the bilge and see nothing else coming in. The check valve is very low near the pump, so I dont think I am hearing the gurgling sound from the CV. It is possible that the CV may be taking a while to break then when that happens, I am hearing the gurgling from the siphon?

I think a 2nd pump would be a good idea, would you install this pump lower than the bigger one, or just raise the float switch on the big one so the small pump would kick on first? Is there a way I can use the same discharge threw hull for both pumps?

sailingdog · #5 (**permalink**) 08-13-2007

Quote:

Originally Posted by dsbentley

sd, I agree with what you are saying, but I question the fact that the boat has been working fine with this configuration for 20 years so something has recently changed. I know there is no other leak's as I have monitored the bilge and see nothing else coming in. The check valve is very low near the pump, so I dont think I am hearing the gurgling sound from the CV. It is possible that the CV may be taking a while to break then when that happens, I am hearing the gurgling from the siphon?

You could be hearing the gurgling noise from the leaking check valve traveling up the hose to the anti-siphon valve.

Quote:

I think a 2nd pump would be a good idea, would you install this pump lower than the bigger one, or just raise the float switch on the big one so the small pump would kick on first? Is there a way I can use the same discharge threw hull for both pumps?

Install the pump as low as possible, and raise the float switch on the bigger pump...that way the small pump runs for the maintenance "bilge pump" work, and the larger one kicks on only when the water starts exceeding what the little one can handle.

If the hose to the through hull slopes downward from the anti-siphon valve, which I believe it will, you could put a T-fitting in it, and use it for both, but you'd need a anti-siphon valve in the smaller hose as well, and it should rise to the same height as the anti-siphon valve in the larger one.

dsbentley · #6 (**permalink**) 08-13-2007

I do have room to install a T after the siphon, what size line would you use on the small pump? How big a pump should I use? I guess the big pump would only come on in an emergency and I could still cycle and test it by turning off the small one every once in a while.

sailingdog · #7 (**permalink**) 08-13-2007

I'd go with a 1/2" hose and as small a pump as you can. That way, if the hose back flushes through the pump, the amount of water that it lets back down will be minimal.

hellosailor · #8 (**permalink**) 08-13-2007

"Is it possible that my check valve is going bad "
AFAIK check valves ALWAYS GO BAD the only question is how long it takes for that to happen. They also are a significant obstruction blocking the discharge hose. Convenient, but not the best way to go.

sailingdog · #9 (**permalink**) 08-13-2007

HS-

That's why I don't recommend them... they tend to limit/restrict the pump's ability to push water out of the boat.

dsbentley · #10 (**permalink**) 08-13-2007

Thanks Guys, I will look into installing a smaller pump with a 1/2" hose and will check out the CV on the other pump. It sounds like I sound just plan on replacing the CV at this point.