What temp should I set my aquastat for maximum efficiency?

I have a Weil McLain WTGO-4 boiler and a Honeywell aquastat with a low and high setting. Right now it's set at 120 low and 150 high. From what I read it seems that every house is different for where the optimum setting should be between comfort and efficiency. My question is how do I know where the right range should be for my house? I'm concerned that my boiler is cycling too often and for too short a time. Sometimes it only runs for a couple of minutes - not long enough to get the radiators hot enough, but it does eventually get the heat up to the 66-67 degrees I keep my thermostat. Is this short cycling bad for my furnace? Should I bump the high up to 180 and the low up to 140? Will that waste too much energy up the chimney? At $3 a gallon of oil I'd like to save as much money on energy as possible and if that means wearing fleece jackets and pants so be it. If I do change the settings, what are the signs I should look for to make sure that it's working correctly. This system is also a tankless water heater and it seems to provide hot enough water for showers and baths, I just concerned about the constant cycling. A little more info - It's been between 26-35 degrees for the past week.
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You should have bought a condensing unit of 92% + if efficency was a concern , I dought you will see any difference if less than 5 minute cycles are seen, change the wall thermostat Swing amount for longer cycles and get a condensing unit of 92+
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wrote:

You need someone that has a clue to be working on it. The "operating temperature" gets set according to the type of heating elements you have. If its short cycling it will cause great harm. Mainly in the way of condensation, rust and part self destruction. Bubba
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