Drain Hose Size for Rule 600?

[Gone2long]

I am a new owner and have a Rule 600 bilge pump with a 3/4 inch nipple on the output side of the pump.

Apparently, the original owner used a Rule 1,000 pump and installed a 1" drain hose to match the 1,000 output nipple for the pump.

Apparently, the Rule 1k pump failed and he replaced it with a Rule 600 pump, connecting it via a reducer, to the 1" drain line.

The pump works, but gives me significant "blowback" making it less than efficient. Might I be better advised to replace the 1" hose with 3/4 inch?

Sorry for all the guess work, but the original owner has made himself unavailable for comment, and I might be willing to suffer the inefficient configuration rather than try to replace the hose, which is very difficult to access where it connects to the through hull.

All comments appreciated,

G2L

[Pete7]

Or replace it with a Rule 1000 and put the 600 somewhere else. We have a little one under the engine as its the most likely place to have a leak. It discharges into the cockpit with the idea that if the crew get wet feet they might be tempted to investigate were the water is coming from.

Pete

[Gone2long]

Originally Posted by Pete7

Or replace it with a Rule 1000 and put the 600 somewhere else. We have a little one under the engine as its the most likely place to have a leak. It discharges into the cockpit with the idea that if the crew get wet feet they might be tempted to investigate were the water is coming from.

Pete

Yeah, thinking this one over, as I actually have two 600s, and it will definitely be cheaper, if dauntingly difficult, to use the 600s and just change the hose if installing a smaller hose might solve the problem. I have a small bilge and can only use one pump at a time; so the second 600 serves only as a spare.

Gotta know if changing to a smaller hose will work before putting myself through the hassle of changing the hose. Not excited about coughing up the money for a 1,ooo and letting two pumps go unused.

Thanks for your input,

G2L

[a64pilot]

Call me stupid, but I'd be tempted to see if passing a thinner pierce of 3/4" vinyl hose inside of the 1" would fit., if it did it would be cheap and easy, plus you leave the option open of going to a bigger pump one day if you wanted to.

[Cheechako]

What do you mean by blow back?

[Gone2long]

Originally Posted by a64pilot

Call me stupid, but I'd be tempted to see if passing a thinner pierce of 3/4" vinyl hose inside of the 1" would fit., if it did it would be cheap and easy, plus you leave the option open of going to a bigger pump one day if you wanted to.

Actually, I thought about doing just that, but the problem is getting the 3/4" hose attached effectively to the thru hull. If I just push it through the old hose, it wont seal well onto the through hull nipple.

Does seem to make sense to keep the old hose in place, even if I go with a smaller one for now.

Thanks,

G2L

[Gone2long]

Originally Posted by Cheechako

What do you mean by blow back?

The pump sucks up water and spits some out of the boat, but then, a bunch flows right back down into the bilge, as soon as the pump shuts off.

I had a check valve in the line to stop this from happening, but the valve kept sticking shut, so I took it out.

G2L

[Bill Seal]

Changing back to a larger pump or going to a smaller one isn't going to change the amount of water in the discharge hose which returns back to the bilge when the pump turns off.

[Gone2long]

Originally Posted by Bill Seal

Changing back to a larger pump or going to a smaller one isn't going to change the amount of water in the discharge hose which returns back to the bilge when the pump turns off.

I am not talking about going to a smaller pump. I am talking about going to a smaller hose.

However, I think I understand your point. You mean that, if I use my Rule 600 with a large hose or small hose, the volume of water that falls back will be the same because the volume of water pumped out is consistent, no matter what size hose it is pumped through. Is that your point?

If so, I am not sure that your point is correct because the water in a 3/4 inch hose will be pumped through at a higher pressure, than would be present, if pumped through a 1 inch hose, due to the smaller hose diameter. That extra pressure may kick more water out of the drain line and let less flow back to the bilge as a result.

I am not a physicist, but, it seems that a smaller hose creates a "jet" effect, like pushing a set volume of air through a small hole or jet engine.

If I am wrong about that, please explain.

G2L

[HopCar]

Yes going to a smaller hose will reduce blow back. Never heard it called blow back but I like the term. Maybe Flow Back would be a better term.

I had a customer with a small space that accumulated water. He installed a small Rule pump designed for 3/4" hose. The flow back was enough to trigger the pump again and it would continuously cycle on and off. He reduced the hose size to 3/8" and eliminated the problem.

[topmast]

Going to a smaller hose will definitely reduce the 'flowback' but when the pump is called to emergency duty, what then? usually two pumps .big one sits higher in the bilge and hopefully only gets used when the inevitable nasty happens.

[Cheechako]

Originally Posted by Gone2long

The pump sucks up water and spits some out of the boat, but then, a bunch flows right back down into the bilge, as soon as the pump shuts off.

I had a check valve in the line to stop this from happening, but the valve kept sticking shut, so I took it out.

G2L

Yeah, This is normal for most pumps and has nothing to do with your particular hose or pump. On larger boats some people put in a small diapragm pump or etc to excavate the last bit.
The difference in the hoses if your hose is 10 ft long is .17 gal

[HopCar]

Topmast, in the op's situation he won't reduce the capacity of his pump by dropping down to the hose size the pump was designed for.

My own boat is set up as you describe. I have two 900 GPH pumps low in the bilge and a 3500 mounted higher. The 3500 never comes on but it's there if I need it.

I do think the OP needs more than 600 GPH pumping capacity and he should set it up as you describe.

[Cadence]

Originally Posted by Pete7

Or replace it with a Rule 1000 and put the 600 somewhere else. We have a little one under the engine as its the most likely place to have a leak. It discharges into the cockpit with the idea that if the crew get wet feet they might be tempted to investigate were the water is coming from.

Pete

Great logic and I am not being factious.

[Dave22q]

Seems to me that hoses will always empty back to the pump unless stopped by a check valve which can raise failure issues. The amount of flow back is the volume of the hose from the high point back to the pump. Velocity has nothing to do with it. All the water in the hose when the pump stops pushing will flow downhill.
The reality is that no bilge pump can totally empty the bilge due to the design of the cut off switch. If you want dry use a hand pump as much as you can then a large sponge or jack the boat up and drill a hole in the bottom :>). If anybody has discovered an easier way I would love to hear it.