Interesting Grundfos SQE Data

[Kent M]

I've had a Grundfos SQE 15-250 with CU301 installed since 12-2003.  No water related problems with pump or controller, though I did have to put noise filters on the circuit to prevent interference with our X-10 system.

Being somewhat of a techno nerd, I acquired an R100 remote a few years ago to be able to read the data stored in the pump.  As of 8/10/2015, here are the numbers reported by the system, with a few estimates of my own:

Power Consumption (kWh):  1,088*
Number of Starts:  176,471
Operating Hours:  1,016
Starts Per Op. Hr.:  173.7
Starts Per Day:  41.5  (4,248 days between 12/23/2003 and 8/10/2015)
kWh Per Day:  0.26

Estimated Gallons Pumped:  609,600   
Estimated Gallons Per Start:  3.5   
Estimated Gallons Per Day:  143.5

* The R100 reports a 40W load, when the pump is off.  If that is accurate, then an additional 4,000+ kWh of electricity were used in standby mode.  I need to measure that with amp meter to verify.  Pretty sad if true.

The pump is rated at 15gpm at 287' at high speed.  Our pump is hanging at 80' in our 130' well with static at 30'.  This pump could probably do 22-23 gpm from 80'.  I've conservatively used 10 gpm in the calculation for estimated gallons, since the pump is likely never running at full speed.

It's pretty obvious that the installer didn't do any sizing calculations, but probably used this same pump for every residential job.
 
We've never had the 2 gallon tank that Grundfos suggests, but had a fairly new 36 gallon when installed and a 20 gallon replacement for that installed 4 days ago.  I imagine the number of starts would be considerably higher had we been using the 2 gallon tank.

Ok, sorry for the long winded post, but hope someone finds it useful.

[Cary Austin]

That is very interesting stuff.  The 40w when the pump is off doesn't surprise me.  It is like any computer in stand-by mode, it is still using electricity.  The most interesting thing is that it is still working after 12 years.  Most never make it that long, and many have replaced the controller 3 or 4 times in the first 5 years.

[Kent M]

From what I've been reading, it kind of surprises me, too, that it has lasted this long.  Perhaps we just happened to get a good one (though I've now just cursed it).  We also have a whole house surge protector - maybe that has absorbed some small spikes that would have otherwise toasted it.

I'm thinking of getting rid of the CU301 and going to a CSV1A.  It might be nice to hang on to the CU301 as long as the pump lasts to be able to pull statistics every couple years.  The pump itself stores the data, though I'm not sure if it's running as an SQ if it can self update the data.  If not, I could probably sell the CU301 and R100 to pay for the CSV1A.

[Cary Austin]

Well it is very lightly used with only 143 gallons per day.  That usually has a lot to do with how long they last.  Power surges can take them out but usually it is just a communication error between the controller and the motor.  They call it generation 7 but that means those pumps have gone through about 7 upgrades since 2004.   

One thing they keep changing is how many times it will lose communication with the motor before showing a fault.  I think yours was set up for about 250 times and now they are at 1000 times before it shows a fault.  All that means is that when they lose communication they revert to acting like a regular pressure switch system with 15 PSI in between on and off.  When that happens your larger tank is of great benefit as it slows the cycling down.  It has probably been doing that a lot and you just haven not noticed.

Now when the CU301 is working correctly there is only 2 PSI between the on and the off, so the large tank is not helping much.  This is why you only get 3.5 gallons per start and there are 41 starts per day.  You just don't get much out of any size pressure tank with only 2 PSI between on and off.  I am not sure if it even keeps up with those stats when it is in bypass or lost communication mode.

I don't think you will be able to get those statistics if you remove the CU301.  But doing so and replacing it with a CSV and a regular pressure switch will keep it from using 40 watts of power all the time, even when the pump is off.  I can see where that would really add up.  With the CSV system the regular pressure switch would shut power off to the pump completely when the water is not being used, so it wouldn't be using that extra 40W all the time.

If you had any irrigation, a heat pump, or anything that used much water, I doubt that system would still be working.  The SQ pump part of it probably would, but the CU301 controller would probably have needed replacing several times by now.