For the life of me, I can't figure out why you have one float controlling two TDRs. You usually see 2, NC, open on high water float switches in series driving a control relay. A NO sealing contact of the relay would be paralleled with the lower setting float switch. You really think of the lower setting switch as closing on low water, instead of opening on high water. There are various switches that allow deadband adjustments with a single float but those are usually touchier to adjust. Is there more to this that you're not sharing? Do you just want to open the fill valve at x" and close it at x" + y" ???
I work with some used oil day tanks that have reed switches in a SS shaft. SS floats with magnets travel berween collars. I have seen them ordered and installed with the wrong contacts. Fortunately I was able to switch the contacts by moving the collars up or down a little. I have never had the units stick. They all pick cube relays @ 120 VAC.
The only pump controls I work with that use TDRs require pre-libe of bearings on long pump shafts. The floats and alternator trigger a >= 1 min pre-lube and then start the pump(s).
Are you using these delays for alarms or to detect if you haven't filled the tank within the allowed time?
Joe
