Lake Pump problems, best system design?

[sbpetrok]

i just moved out to a lakehouse last year. It had a sprinkler system with a centrifugal pump. The pump motor burned up when one leg of the 240v power dropped out (breaker tripped).

I hired a guy who replaced the pump/motor with a National Pump EC-201, 2hp centrifugal pump. While he was at it, he replumbed the supply with new pipes and foot valve.

The foot valve had a metal "cage" like a colander to keep big junk out of the line... unfortunately, the lake has a muddy bottom, and the "cage" got covered with mud and scale to the point that it clogged up. The pump runs on a timer and pump start relay, so I wasn't there to notice it was running dry. The pump will no longer hold a prime or draw sufficient vacuum to supply itself. (The foot valve is working fine, now that I cleaned off its enclosure.)

My question is: what shall I do to re-configure my system to prevent such an occurrance in the future? Is there a low pressure shutoff switch (or something) I can install to prevent the system from running dry in the future? How about a relay that won't power up the pump with less than 220v?

Thanks!

[rideauriver]

hi sbpetrok,

The spe******ts that installed my foot valve enclosed it in a bag that you can by at HDepot (screened bag) and placed the foot valve in a milk crate with a couple of heavy rocks to stop it from flowing. That way the valve never touches bottom and stays in an enclosure that cannot be intruded by other objects to prevent further blockage.

[sbpetrok]

hi rideauriver,

thanks for the suggestion! However, pretty much anything in our lake eventually gets crusted over... i think i just need to clean off the screen to the foot valve every quarter or so.

but there are countless other things that could cause the supply to fail or the pump to lose its prime - say a wakeboard or tree limb crashed into the supply pvc and cracked it, so the supply pipe drained empty down to the lake level...

I want to install some way of shutting off the power to the pump if the pump is running dry (for whatever reason) in the future. Can anyone help?

[speedbump]

He didn't do you any favors installing an end suction centrifugal. They are harder than H*** to prime. He should have installed a self priming centrifugal.

If you drop a leg on 230 volts, nothing will happen to the motor, because there is no complete circuit. If the other leg goes to ground somehow on the pumps side, it could then try to run on 115 volts which would certainly do damage.

I have a device that stops the motor if the pump gets hot. But you would need an amperage sensing unit to protect it against low voltage.

Did he sell you a plastic or brass impeller? If plastic and it lost it's prime, the impeller is probably nuked.

bob...

[sbpetrok]

thanks bob!

would be interested in the hot pump shutoff, can you tell me more?

fortunately, we've gotten some rain lately, so the pump has not been missed so much.

I'm not sure if my impeller is brass or plastic... it SEEMS like it would be easy enough to replace it either way, though - if I could find the parts. Am I wrong to think so?

[speedbump]

It's called the Hot Stop Thermostat. I've used them off and on for years. The first company that make them was here in Florida. Don't know where they went, they just diasppeared. Now there is another outfit making them here in Florida as well. They can either screw into the pump or they can be strapped on with a stainless steel hose clamp, (provided). They turn the pump off at 110° and back on at 90°. You break on of the pumps hot wires to make it work. There are kits to hook it up in conduit with all the goodies provided. They never got their website up and running so I can't send you there. If you want to know more, just call me at 813-677-7867 and I'll try to be more specific.

bob...

[Bob NH]

You should put a large piece of iron or concrete out there for an anchor, and then use a float to lift the foot valve off the bottom while held down by the anchor. A 1.5 gallon bleach jug will provide about 12 # of buoyancy; 1 gallon about 8 pounds.

The float can be on top or submerged, depending on how you tie the line. Float on the surface is more convenient if it doesn't bother navigation.

The foot valve should be suspended about mid way between the surface and the bottom. That way, anything that sinks will be below it, and stuff that floats will be above it. My customers who pump 1 to 2 million gallons in a summer never have to clean the strainer.

[rappini]

I presently have a pump that was used on our well when we owned a Cottage and now we live on the Water. We also have an irrigation system installed and operational. What I would like to do is install my pump so it can draw from the Lake and hook it into my existing irriagation to water the Lawn. In reading this forum someone mentioned a Foot Valve I'm assuming that goes into the Lake but then how do you tie into the Irrigation and where?

Thanks
Rappini

[speedbump]

You would need a lake strainer like the one pictured on This Page. You will also need a check valve just in front of or inside of the lake strainer.

Next thing is to try to figure out how many gallons per minute your sprinklers need so you can pick out the right pump. Otherwise your pressure will either be terrible or it will be great while wasting lots of electricity.

bob...