I have a wc4 peerless w/ beckett oil fired burner. I only need about 90K btus (since I converted to all radiant from steam)thus I reduced the nozzle size to .85 Gph now for about 5 years running w/ 11% co2. I change the nozzle/oil filter every year and clean the boiler fins with a special wire brush. PITA but it's very efficient. Now, I want to extract even more efficiency out of a cast Iron boiler since Oil prices are insane again. I expect to replace this with an On demand heater in the near future. My boiler high was set at 170F/120f with 25F difference. If I reduce this High Temp to around 140F high (my max radiant temp)my pumps 011 keep spinning longer times? So I save on oil but my pumps keep on spinning burning electric. My delta was 20F now its 40F which is fine but how to adjust the pumps so that they shut off normally? Taco claims they have an adjustable pump set by delta T which is what I want. A Higher Delta w/o a higher electric Bill. I have a S steel liner with burner still running long enough to reach hot temps in exhaust. Any input would be greatly appreciated. I don't care about a boiler life since it dry fires 20 gallons. Thanks Mike