Subject: [Shop-talk] remote tank sensing, the epilog

From: Mark Miller <[email-masked]>
Date: Tue, 23 Sep 2014 16:20:52 -0700

I wrote: Hi. A friend asked me to come take a look when their water 
system failed recently. Problem was easy to diagnose and fix (a leak 
caused the tanks to drain out faster than they filled up. Leak fixed and 
the tanks refilled within a few days) and I [foolishly] offered to help 
set something up so it won't happen again as catastrophically. The 
situation: there are some spring fed storage tanks about 50-100 feet 
away from the nearest source of power. They typically remain full or 
nearly so and there is a system to keep them full (manual float valves). 
I would like to add some level sensors in the tank to indicate when the 
tank is less than 1/2-3/4 full (something might be awry) and another 
when the tank is almost empty to disable the (remote from the tanks, but 
located near power) booster pumps to prevent them from running dry and 
possibly overheating. The most straightforward would be to put sensors 
in the tanks and run wires to relays at the pumps and indicators, but 
that would require trenching. Anyone know of a good source for some 
battery operated transmitters and battery or wired receivers? These are 
rather slow changing signals, so something that transmitted only at a 
change or had a transmit interval that could be set to a long time would 
be better for battery life (but changing batteries isn't that big a 
deal, just a pain). Thank, o all knowing list!!

Thanks all for the excellent suggestions but in the end the problem got 
easier than I originally thought it was.  Seems there was an empty 
conduit buried along with the original water pipes (yaaaaaay thinking 
ahead!!!!) so I went with a simple brute force solution.  2 float valves 
(one for a 'not full' alarm and one to disable the pump if the water 
level dropped too low) in each tank (one for irrigation, one for house 
water) and it works fine.

Mark Miller
waiting for rain in dry Northern California or all the above is moot anyway.
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