So I went up to my cottage last week. When I close it down, in the fall, I drain and blow out all the pipes inside the cottage with compressed air and put anti-freeze in the pump. I am in Canada and it gets quite a lot below freezing in the winter.

When I primed the pump and turned it on I got a pretty good flow of water but it would not raise the pressure past around 20 to 22 psi. My pressure switch is set to around 22psi on and 42psi off. The air in the tank is set at around 20psi. The water out a tap was about 2 to 3 gallons per minute but the guage on the pump would never go higher then about 22psi. The pump is a 1/2 Hp, single line jet pump. I pull my water from the river that is about 10 feet below the pump in elevation. I have used this system for 13 years now without issue.

It was pretty cold last weekend so I figured it might be ice in the 1 1/4" incoming poly line. When I go up on Thursday I suspect any ice should be thawed for sure, if it wasn't already. My idea is to try the following:

1) Run the pump and if the problem was ice perhaps it will work now.
2) Look and finely sand the points on the pressure switch with a points file. See if they are pitted. The connections looked fine when I gave them a visual last week.
3) Open up the front and check the venturi and nozzle for blockage. Mine are plastic so they might be cracked from perhaps ice over the winter. The pump casing is not leaking from any crack. The pump sounds fine when it runs. Nothing sounds broken but that doesn't necessarily mean nothing is.

Other then that I have no other ideas why my pump will not build pressure to 42psi and shut off, like it use to. Even when I shut off the pressure tank valve and all other taps in the house, I would usually get a short cycle experience but last week the pump just kept running even when no water was able to go anywhere. There is no leak since the water stays level in the pump when I leave it over-night and I am not getting any air bursts or anything like that or losing prime.

Would anyone have any other ideas for me to look at while I am getting into this problem.

 

If it were a contactor issue.... the pump would not run.
It's either a blockage on the suction side of the pump or the pump itself.

 

Sure. I thought perhaps the points might be corroded and perhaps a high resistance might be creating a voltage drop that might reduce the power of the pump. Long shot I know.

Other then a clogged venturi any idea what I might look at with the pump if it were the problem. Do pumps just lose their sucking power after a while?

 

The pump impeller can get worn down from use..... especially in a sandy or high mineral environment.

 

In spring opening up a cottage after winter I suspect the venturi. Rust or sediment can develop when the system isn't being used. Then you hit the pump for the first time of the season and chunks break free, circulate through the system and get strained out by the venturi.

I had it happen every year with a cottage of mine. It would usually re-clog a few times so I would have to keep pulling the well and clean the venturi until all the gunk was worked out of the system. I eventually got in the habit of sticking the foot valve in barrel of water with the venturi removed. Since I had the foot valve at the surface the pump was able to run and circulate the water and the chunks settled to the bottom of the barrel. A minute or two of running was enough to flush the system clean. Then it would fine all summer long.

 

OK. Thanks.

When I look up the specs on a jet pump like mine I see that the nozzle that goes inside the venturi (mine is in the pump itself) is sometimes only about 1/8" in diameter. I use to draw about 5 gallons per minute with this pump so I have to assume most of the water does not flow through that nozzle. I can't imagine 5 gallons per minute flowing through a 1/8" dia. hole.

I am sure there is a lot of technology in these things that I don't understand. It is usually times like this, however, where the learning curve rises rapidly.

 

OK. So my problem ended up being crud in the venturi. It was pretty clogged up with grit and crud. Anyway, cleaned her all out and we are now back to pumping water to the proper pressures. Thank you all for your suggestions. Always appreciated.

 

Glad you got the problem taken care of.

 

You are correct, the full pump volume does not get forced through the venturi. Your pump may actually pump 8 gallons per minute but you only get 5 gal/min out of it with the other 3 being recirculated back down the well to power the venturi. That's why the two pipes going to the well are usually different sizes. Only a portion of the pump's output is sent back to the well for the venturi. The venturi then helps push the water up to the pump where the real pumping occurs.

 

In my case it is only a shallow well set up with a single input pipe but it does have two chambers in the front of the pump. The venturi is in the top one that is level with that input pipe and then there is an empty larger chamber below it where water could flow freely as well. Looks kind of like a deep well ejector set up right inside the pump itself.

In any case it still seems pecular to me that my water flow could ALL becoming through the venturi. Even though I have heard that the venturi will adjust the velocity of the water, I would think that it still should create some kind of restriction of that volume as well. But I am far from an expert.

My pump is rated for 9 gpm but I always assume that the maximum flow rate is when water is level with the pump and all output connections are the same as the pumps output. In my case 3/4". Of course my my pump is about 10 feet above the water level and I was measuring that flow rate through a 1/2" pipe that probably had a bend or two before I saw the water.