If I read this thread correctly, you have a submersible pump (you write of needing back pressure on start up) pumping out a basement on what is a very low head and this is causing you concerns about power consumption.
OK first thing is to take a bucket of known volume, place it under the outlet pipe while using a stop watch (phone, actual stop watch) and come back to us with that figure plus an accurate lift (lowest water level to the point at which the discharge pipe leaves the basement), we will ignore the NSPH of the discharge pipe from highest point to actual discharge as it is small.
So precisely what pump do you have in service currently? And what is the secondary pump?
Empowered with this knowledge we can advise a solution, Simen's solution is valid, but I suspect would still require a pump because of your location relative to river as opposed to just general ground water..
Allan in Far North Queensland Australia [(FNQ) F*****g Nothing Quickly]
Hello..
Yes, the primary pump is a "submersible" pump. No, I certainly didn't mean to say that it needs back up pressure to start. I did say that I wonder about the amount of head pressure (weight of water in the hose) causing a increase in power consumption.
....As I read it you have a man doing a boys job, if it is a true submersible pump and I doubt that as it would have burnt out by now (max. 3 starts/hour to allow windings to cool off).....
It certainly IS a "true" submersible pump, The water temp is COLD, although I didn't check it with a thermometer, but a wild a$$ guess is it's about 45-50f. And it had better be a "MAN" because a "boy" would be way way over his head (and fast).
Latest laps time is 318hrs. and consumption is 99.1kwhrs
99.1/.740 *3/4hp* = 133.9 total hours the pump has run.
As I said, it's a Wayne 3/4hp and a few years old, here is a link to it's current replacement (although I'm sure that the over all specs really haven't changed)
http://www.waynepumps.com/solution-center/sump-pumps-cast-iron/cdu980eI happen to have another Wayne also 3/4hp as a backup (new not installed)
The secondary pump (installed in a dry sump/collection basin) is a 1/2hp pedestal style pump and it's back (yes, a back up to the back up) up (installed along side the secondary pump) is another 1/2hp pedestal pump.
As a back up to the back up back up is a 1/3hp "skimmer" pump, but it is all manual (doesn't have a float switch).
I post here not so much to get ideas/opinions... but more so to WHINE and also to point out to those who "think" that they have a wet basement (and whine about it) that perhaps they really haven't much to complain about.
Since I've been posting here... and keeping a close(er) eye on the Kill-a-Watt meter it has occurred to me that there might be a "better" system. So Now I will pose a question and looking for ideas/opinion.
I wonder if a variable speed pump might not be more efficient?
Perhaps, rather than having a simple float switch, a "analog" type sensor to monitor water depth (in sump pit) and ramp power up when the water is rising fast and ramp it down (and off) when/as water flow slows down.
This, in theory would greatly decrease that extra current draw at each start-up (run cycle).