Blige Pump Backflow

[JohnO]

Purchased our new-to-us boat about 6 months ago and just got around to a thorough bilge cleaning / repainting and replacing the rather filthy bilge pump and hoses (Rule 2000 manual with a float switch). Problem I'm having is the distance to the thru hull results in backflow which makes the pump cycle constantly. I tried raising the float switch (a possible solution that I read somewhere). The physics didn't totally make sense to me, but I tried it anyway. No avail. Still the same problem, although I can at least manually suck out some water once it starts cycling.

I've read that others have just put in a check valve, which I don't want to do, and shortening the run is not feasible. I'm slowly tracing the water (which I believe is coming from a leaky water heater and possibly condensate lines from the fridge/freezer), but need a working bilge solution regardless. Could use some help on how best to address.

I'm sure this topic has been covered at least a few times, but having trouble finding just the right thread - so feel free to point me in that direction if easier.

 

[rslifkin]

Raise the big pump and float a little higher in the bilge. And then add a smaller pump with smaller hose to reduce backflow from removing nuisance water.

 

[Comodave]

I put a Dri-Bilge pump in our boat. You can program it to come on and off throughout the day. It sucks up virtually all the water in the bilge that is leftover from the bilge pump.

 

[Cigatoo]

I just solved this problem. Don’t waste your time with smaller pumps etc. Installed a Whale Gulper pump with a Water Witch switch as a primary pump. The rule 2000 is now high and dry. For emergencies only. The Water Witch will run the pump for 15 seconds after the bilge is dry. No back flow at all. Attached the pump hose to a length of pvc pipe. The Water Witch switch is attached an inch off of the bottom of the pvc.
https://www.westmarine.com/whale-pu...0dF_dBBaKHWByKrbfNOTE13rZJkH_hYMaAigIEALw_wcB
https://waterwitchinc.com/product/model-101-bilge-switch/

 

[jleonard]

The solution to that in my old Mainship 1 was to use a diaphragm style bilge pump. The diaphragm acted as a check valve. It was not a high volume pump but at the lowest part of the bilge it worked perfectly.
My high volume pump I mounted a little higher.

 

[Spinner]

Re the Whale Gulper pump installation, how does the water get overboard? Does it share the Rule pump through hole?

 

[Cigatoo]

Re the Whale Gulper pump installation, how does the water get overboard? Does it share the Rule pump through hole?

It has its own 3/4 inch hole. I set it up as a totally separate system both plumbing and electrical.

 

[tiltrider1]

What is your issue with a check valve. Todays check valves are pretty simple, nothing more than a rubber flap, nothing to corrode nor clog.

 

[Alaskan Sea-Duction]

What is your issue with a check valve. Todays check valves are pretty simple, nothing more than a rubber flap, nothing to corrode nor clog.

Most bilge pump manufactures suggest not to use check valves.

 

[OldDan1943]

What is your issue with a check valve. Todays check valves are pretty simple, nothing more than a rubber flap, nothing to corrode nor clog.

1. never share a bilge pump overboard with anything. One pump, one overboard.
2. check valves can stick closed

 

[tiltrider1]

1. never share a bilge pump overboard with anything. One pump, one overboard.
2. check valves can stick closed

Modern check valves don’t stick close. They stay open and only close when water runs backwards. In order to be in compliance with ABYC you need to have your through hull a minimum hight above the water line, (I can’t look up the spec at the moment.) or the hose must have a loop that is at the minimum height or there needs to be a check valve. Surveyors have been cracking done on this lately on older boats.

A loop maybe why JohnO is having the back flow issue.

 

[sunchaser]

There are some good suggestions here John O. I've a question, where is the water coming from? We've 4 separate bilge areas on our vessel and all are dry as a bone.

 

[JohnO]

Agreed Sunchaser - good suggestions. kind of leaning towards the diaphragm pump idea. As for water, I think it's coming from a leaky pressure valve on my raritan 1700 water heater. Stuck a giant cup under it one night and it filled it up over a 10 hour period. I can also hear the pressure pump run frequently through the day and night. Think I also might have some residual water from condensate lines, but haven't had a chance to check those yet.

 

[JohnO]

Cigatoo - do you have a pic of your setup? I'm interested in duplicating.

 

[jeremy.st]

I just solved this problem. Don’t waste your time with smaller pumps etc. Installed a Whale Gulper pump with a Water Witch switch as a primary pump. The rule 2000 is now high and dry. For emergencies only. The Water Witch will run the pump for 15 seconds after the bilge is dry. No back flow at all. Attached the pump hose to a length of pvc pipe. The Water Witch switch is attached an inch off of the bottom of the pvc.
https://www.westmarine.com/whale-pu...0dF_dBBaKHWByKrbfNOTE13rZJkH_hYMaAigIEALw_wcB
https://waterwitchinc.com/product/model-101-bilge-switch/

I had the same problem with a boat I purchased recently and did the same as Cigatoo. In installed a Whale Gulper which runs first also with a Water Witch. The Rule is in the same place but I changed the float switch with another Water Witch that is about 3 inches higher than the Water Witch for the Gulper.

The Water Witch runs for approximately 15 seconds after it's dry so that may resolve your back flow issue. The sensor will need to be higher and you will have more water in the bilge.

I really like using the diaphragm pump as the primary maintenance pump. I have a stuffing box and a small deep bilge so it runs a few times a day.

 

[Nick F]

Modern check valves don’t stick close. They stay open and only close when water runs backwards.

Sorry Tiltrider - I must disagree. Any check valve can stick closed.

Furthermore, a properly working check valve (i.e. one that does not stick closed) will hold water in the section of hose above it (that is why you are installing it - to stop the backflow). The bilge pump will have to overcome this "head" of water before it can get any flow going at all. Some centrifugal pumps (the pump type used in common bilge pumps) will not generate any head until they have flow - they just cavitate. I have seen this happen. Its difficult to believe, but the pump would not start pumping until a bit of leakage was allowed before the check valve.

Please - NEVER INSTALL A CHECK VALVE DOWNSTREAM OF A BILGE PUMP!!

Regards,
Nick

 

[Guilhem]

Nick thanks for the explanation. Ironically the last bilge pump I bought came with a check valve. It's a small Rule pump foe the shower sump, and I took off the check valve as it wouldn't fit anyway, but reading your very interesting post and seeing that it was provided by the (fampus) manufacturer is puzzling.

 

[Guilhem]

1. never share a bilge pump overboard with anything. One pump, one overboard.

May I ask why? My boat is plumbed this way, one overboard is used for a bilge pump and a sink. Plumbing looks original. What issue may arise?

 

[LarryM]

I put a Dri-Bilge pump in our boat. You can program it to come on and off throughout the day. It sucks up virtually all the water in the bilge that is leftover from the bilge pump.

Same here, big fan. Over a year ago I installed one in main cabin bilge and another in the engine room bilge. They run about ~5 minutes at noon and the bilges stay bone dry. I also routed the AC and dehumidifier pan drains to the shower sump which really helped in the cabin. No more odors either.

 

[koliver]

You need an anti-siphon loop that has a working siphon break. Sounds like yours, if fitted, is plugged, so you are getting the contents of the whole length of the hose draining back into the bilge, instead of only the length to the anti siphon loop.
Most loops have a twist off valve on top. twist it off and clean it, re-assemble and it should work.

 

[Cigatoo]

May I ask why? My boat is plumbed this way, one overboard is used for a bilge pump and a sink. Plumbing looks original. What issue may arise?

That’s the way the Grand Banks are set up. They work fine with no issues.

 

[rslifkin]

May I ask why? My boat is plumbed this way, one overboard is used for a bilge pump and a sink. Plumbing looks original. What issue may arise?

If the plumbing layout is good and the discharge is big enough, it'll work fine. But if it's not done well it can either restrict output or cause back flow through another item connected to that discharge. So as the safer option it's generally recommended not to do it.

 

[Hippocampus]

Is it permissible to use a small secondary pump and have it drain into a AC condensation pan? Or to a grey water tank? Don’t want to put additional holes through the hull.

 

[Guilhem]

That’s the way the Grand Banks are set up. They work fine with no issues.

Thanks. Not that I had seen an issue, just wanted to understand more.

 

[Cigatoo]

Whale pump in sump

First picture is of the pump mounted to the bulkhead. Left side hose goes to the through hull. Right side hose is attached to PVC pipe. 2nd picture is PVC pipe and three-quarter inch hose barb from Home Depot. All standard stuff. Third picture is the bottom of the PVC pipe with the Water Witch switch attached to the bottom of the pipe. The pipe just drops into the sump. If you don’t have a sump you can add / manufacture a different pick up on the bottom. The white pipe along side the pvc is a piece of PEX tubing that I had. It is simply a conduit for the wires.

 

[Larry M]

We had a sister ship for 13 years and upgraded to a better check valve just after the pump. This stopped the short cycling. Because of the small sump area and discharge hose volume, the check valve was our only option. There wasn’t enough ceiling height for a vented loop and still have the discharge above the waterline. This was a pretty standard set up for the KK42s.

 

[JohnO]

Thanks for posting pics Carl - I like the ingenuity. Seems like that would be a good solution for a regular maintenance pump.