effluent pump

[6sunset6]

Maybe someone here has a clue. I pump effluent 500ft 12 ft uphill to my septic field. I have a duplex pump system with an alternating relay with a second pump alarm. The pipe line is 2". The pumps run around 5 min every 2-3 days. So each pump runs maybe 5 min a week say 5 hours per year.
They are .5 hp 230volt 1 ph pumps. The 12 foot head is well within the pump curves. There is a weep hole to drain the head on shut down. Some of the pumps have weep hole in the base. I have had 3-4 different manufacturers of pumps.
The problem I have is the failure of the pumps. fail to start. Resistance across the two power leads is ok 6-10 ohms. When I open one up usually the centrifugal switch has failed. Out of warrenty of course. Oh yeah 3 years is about average although one lasted 15 years. This is down a 9 foot confined space and I have been doing this for 20 years. Today I replaced one and banged the other around working on pipes and then it failed. I am getting too old for this.
Anybody have a clue?

 

[RedNeckRacin]

TO me it sounds like your pump is way over designed if its running that little? Have you attempted to have anyone actually do the head calculation for you? 500 ft is a pretty decent run of pipe and there are obviously restrictions in the system besides the friction loss in the pipe. From the website below, a guesstimate of an additional 8ft of head for your 500 ft run, plusthe 3 feet required at the end of the laterals, plus an unkown friction loss from elbows and tee's and you aren't requiring a whole bunch of oomph. Looking at liberty effluent pumps here :https://www.libertypumps.com/Data/EngineerSpecifications/FL50_R11-12.pdf It looks like you are pushing around 50-55 gpm depending on what your losses are. That sounds pretty wicked for a septic pump???






PVC Pipes - Friction Loss and Flow Velocities Schedule 4

 

[RedNeckRacin]

TO me it sounds like your pump is way over designed if its running that little? Have you attempted to have anyone actually do the head calculation for you? 500 ft is a pretty decent run of pipe and there are obviously restrictions in the system besides the friction loss in the pipe. From the website below, a guesstimate of an additional 8ft of head for your 500 ft run, plusthe 3 feet required at the end of the laterals, plus an unkown friction loss from elbows and tee's and you aren't requiring a whole bunch of oomph. Looking at liberty effluent pumps here :https://www.libertypumps.com/Data/EngineerSpecifications/FL50_R11-12.pdf It looks like you are pushing around 50-55 gpm depending on what your losses are. That sounds pretty wicked for a septic pump???






PVC Pipes - Friction Loss and Flow Velocities Schedule 4

 

[6sunset6]

Thats pretty much the pump I have. The ones I am putting in now are Meyers 4/10 hp. About the smallest made. The system is designed to pump 250 gallons at a time over the whole field. That's why it runs so infrequently. There are only two of us . I don't think thats why the centrifugal switches are failing.
They are not short cycling which I would expect to cause failure. Maybe the weep holes are plugged and the pumps are starting against a head pressure. That would cause the centrifugal switch contacts and or the starting coil to burn out.. I saw that once the contacts fused shut. Well I have two bad pumps right now so when I open them up I will post my findings

 

[Mendonsy]

I suspect the environment where the pumps are located is at least part of the problem. Is the that area normally wet or high humidity?? Is there any chance of methane buildup?? Is the atmosphere corrosive?? Any of those could cause problems with single phase pump motors that have start and run windings.

 

[RedNeckRacin]

I suspect the environment where the pumps are located is at least part of the problem. Is the that area normally wet or high humidity?? Is there any chance of methane buildup?? Is the atmosphere corrosive?? Any of those could cause problems with single phase pump motors that have start and run windings.

Are you serious? The pumps are submersed in the effluent from the septic tank.

 

[6sunset6]

Exactly total submerged in the worst stuff. They are supposed to be otherwise they overheat. Although it is hard to see overheat in a 5 min run every 3 days. Methane, hydrogen sulfide and one other I can't remember. I posted here a few years ago about going down into the space. The best answer I got was if a candle burns you are ok. I did that , after I opened up and let it vent for a bit. Candle burned fine. To get rid of the smell and get some fresher air down there I put a shop vac hose down to a foot off the bottom and let it run . Works well. I don't breath throu my nose either. I think there are more fatalities by falling, knocking yourself out and drowning than lack of oxygen. Just a side comment. I would like to rail mount those pumps but that means I have to cut the manhole off, and replumb the bottom. ahh I am 70 I can change pumps a few more times . Does anyone know what that black stuff is that builds up on pipes, pumps and everything else? It is really hard to wash off.

 

[Mendonsy]

Well, if you are using that type of pump it is no big surprise that they need to be replaced. There is no way to seal them up well enough to keep the bad stuff out permanently.

 

[DFB]

Interesting discussion to me because my system design is almost identical with duplex alternating pumps and a uphill mound. Except my overall run is much much shorter. I have had the same goulds for more than 10 years of usage now. How are the wiring connection done with yours mine are hard wired into a weather proof sealed box no plugs we cut them off but it still is located inside on the ceiling of the tank.

Once I had problems with the high level alarm "ghosting" the alarm would sound faintly and continuously and it was in the basement so you could hear inside the house especially at night. Turned out there was moisture in the junction box and I guess there was some electrical bridging going on. Getting in there opening it up and drying it out plus resealing fixed the problem. Obviously nothing to do with your problem but I can relate to the nastiness of getting down in there .

I wonder could an obstruction in the line run be causing the pumps to burn out?

I can easily see the drain back from the weep holes happening on my setup.

 

[6sunset6]

Mine was originally spliced in a waterproof box high in the chamber. With pump failures I got tired or soldering and heat shrinking sleeves and the box was not tight anyway. So I drilled a 3" hole through the side of the chamber very high up and installed a 2" PVC conduit to a new box out side. Put outlets in it and plugged in the pumps. The box is not deep enough for straight in plugs so I cut them off and used right angles. Makes it easier to feed the linecords through the conduit as well. caulked all the feed through spaces. Two of the float switch line cords are still spliced in the chamber box, they have not failed in 20 years so leave alone. The third switch connection corroded at a bad splice and I ran it through the new conduit. I had condensation in the control box in the winter so I put a short heat tape around the inside. Took care of it.
I have yet to take the first failed pump apart. later this week. These pumps should really be rail mounted so they can be pulled out from the surface.