Why should the boiler maintain 110 - 12- degrees in the summer? Oh, because you think it will leak? The Weil McLain P series boilers use rubber O rings between the sections. If anything is leaking when the boiler is cold it needs to be repaired. Maintaining temperature is a huge waste of money.
Yes, the high limit on most Honeywell aquastats has a fixed 10 degree differential. You need to have some differential or the burner would short cycle. During a peak heat demand the boiler will and should bounce off the high limit frequently.
The low limit maintains boiler temperature for domestic hot water and has nothing to do with a call for heat except that the heating circulator will not operate until low limit has been reached. In other words if the low is set to 160, the heating circulator will not run until the boiler hits 160. This keeps cold return water from cooling the domestic coil and giving you a blast of cold water in the shower.
If this was my boiler I would:
1- have it thouroughly cleaned, inspected and the burner professionally set up and combustion tested
2- have a Super-Stor or similar indirect water heater installed
3- get rid of the old Enertrol analog re-set controller and install either an Intellicon, Taco PC700 or Tekmar re-set controller.
Payback should be around 5 years.