Lately my well pump has been taking a long time to get to shut off
When I am using 8 -10 gpm continuously (running my geothermal heat
pump), the normal duty cycle of the pump was about 66% i.e. it ran for
4 minutes to get to
shut off(60psi), then for 2 minutes to get to turn on pressure (40psi).
This has been the case for the last 10 years.
Now the off time is still 2 minutes but the pump runs (at 8-10gpm) for
upwards of 45 - 60 minutes before it reaches shut off pressure. Also,
in the past, I could run 18gpm steady and pump would hold 55 - 60 psi.
the best it will do is 12gpm steady but pressure will not get above
Pump is a 1HP submersible Gould 10GS10412 3 wire with an 85gallon
diaphragm pressure tank. Pump amp drain is normal at 10amps. Well is
200ft deep and a static water level at 45 ft. and was rated at 40gpm
drilled 10years ago. Pump is at 160ft. Terrain is granite and I have
never had any problem with water supply; lake is 100ft away and 50 ft
below well head. Pressure in system holds at 60psi when not used or
pumping. Water is moderately hard with moderate level of iron bacteria.
People, could you give me your ideas on what might be going wrong here?
Pump motor was replaced after first 5 years due to motor winding
its another 5 years and trouble again. Same model of pump. Is it the
type or brand of pump? (assuming I have a malfunctioning pump)
At this time of year, it is not unusual for the heat pump to be running
24/7 for days on end. In a normal winter, the heat pump may be on 50%
the time for 3 -4 months.
So a lot of pumping but I understood this pump should be up to it. But
maybe I'm misinformed???? Is this kind of problem a normal failure mode
after heavy use?
What would be an expected life under these conditions?
Thanks for your input!
Sounds like worn impellers. When changed/rebuilt motor, most likely
didn't do anything to the pump. W/ time you've now just basically worn
it out. It's possible there's a leak in the system somewhere, but 10
years of which roughly half is nearly continuous operation is a lot of
operational time. You can probably limp along for a while, but the
increased run time will shorten motor life, so would be best to try to
get it solved as soon as conveniently possible. It will only get worse
and since you already are seeing sizable pressure drop, it's going to
continue to progress. You're losing operational efficiency on the
geothermal system as well as pushing the point at which you may have a
catastrophic failure ultimatly if don't get it taken care of.
BTW, had geothermal, albeit closed loop ground source system in TN and
loved it...are you recycling water or is it once-through?
Thanks for the reply.
Impellers are quite probably the answer but I was thinking that since I
see no sand or grit in my water, I didn't expect significant wear. Also
per the manufacturer's blurb "face clearance floating impeller stack
proven over 40 years as superior sand handling durable pump design".
Also this problem seems to have developed relatively quickly as I have
noticed the reduction only over the last 4 - 5 months. So I thought
something else may be the culprit. But then I'm no expert on pump wear
WRT a possible leak. Would I not see a drop in pressure when the pump
As pulling a pump in winter here (Quebec Canada) is not too pleasant, I
think I will monitor the pump output and may try and limp by until
spring. Will have a contingency plan for heat though!!
My system is open loop with the water disposed into a stone pit which
then drains into the lake. Love the system and the yearly cost is about
1/3 of the cheapest alternative. Also SAFE!!! No combustion, high
temperatures, gases or pollutants.!My last house suffered a massive oil
tank leak contaminating the basement and ground. Worst part, this was
in Massacheusets, a state with the most severe environmental rules
regardong ground contamination. Cleanup was a real nightmare! No more
oil for me!
That it's fine so that it's not visible doesn't mean there are
dissolved and other sediments. Wear is inevitable and you're talking a
lot of running in the mode you're using it as compared to a typical
well-supply. And, "proven over 40 years" doesn't mean a 40-yr
lifetime, but implies the manufacturer has 40-yrs of
development/experience w/ the design. As compared to some other
design/material, it's quite possible it is superior.
The relatively rapid change is also characteristic of pumps and similar
mechanisms in general. The pressure loss is highly dependent on
clearances and drops quite rapidly as tolerances are lost. Same thing
is true w/ air handlers, vacuums, etc. That's why you may lose
essentially all performance.
Probably, depending on where any leak is compared to the pressure
measurement point, of course. But, in general, I think it unlikely,
agreed and that the problem is the pump itself and either impeller or
housing wear (or a little of both) is, imo, the most probable cause of
the symptoms as described.
I gather this isn't also potable water so that losing this pump doesn't
Thanks again for your reply!
Your comments on dissolved minerals and wear, as well as on clearances
and loss of performance make sense to me and appear to explain my
problem. So I'm probably looking at pulling the pump in the near
future. Maybe we will have another balmey day this January!! (Two days
ago temp was 45F:temp tonite is forecast to be -5F and -25F tomorrow
One other possibility, which I think is remote, is that the static
level of the well has lowered from 45ft to 120ft or lower. According to
the pump curve, this would explain my lowered output. I haven't
measured this level in several years but given the stable nature of the
terrain around here, the record rain falls last fall and the fact the
lake level is at 50 ft below the well head and only 150 ft away, I
don't beleive this is the case.............and I hate putting something
in the well to measure the level especially with cold fingers.
BTW this is my source of potable water but I have a number of 5gal
buckets filled to the brim!!!!!
If my pump is the problem, I will have to do some research to find a
pump better suited for this application.
What the water table is and the well regeneration capacity and how fast
the surface recharge rate is are impossible to tell remotely, of
course, but not likely if it's a potable water source that it's at all
directly related to the lake level. But, if you've used this well for
10 years prior to this for the same purpose, it's unlikely it's the
problem, but not impossible. Unless the groundwater there is pretty
quickly renewable and not a problem, however, the once-through nature
is pretty high on consuming water. Is it feasible to have a closed
loop w/ the lake as the heat source/sink? Then you could use the well
only as potable water source and have only a circ pump for the heat
As a deep well pump, doesn't seem like a bad choice and I wouldn't
consider a 10-yr lifetime under the kind of usage you described as a
particularly short lifetime -- in fact, it seems pretty good to me in
comparison w/ our well here of roughly same size and depth.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.