mod-con cycle times

cattledog

I am heating a one zone, 2500 sq ft, concrete slab with a TT Prestige Solo 110 boiler. There is a primary boiler loop through a flat plate heat exchanger, and secondary floor loops off a manifold on the other side. The floor loops are high volumn black iron runs original to a 1949 house). Control is with a Tekmar 510 using the slab sensor only and cyles per hour set to the minimum number=2. Output water temperature is set to the minumum value of 86F. Boiler is modulating down during fire.

Normal operation is for fire times in the 5-10 minute range (depending upon slab setpoint and outdoor temperature) twice per hour. My question is whether or not this frequency of operation and cycle time is putting stress on the boiler hx or other components like the igniter which will shorten the service life.

I have an alternative mode of operation which relys on a programmed schedule with a high setpoint at periodic times. This mode essentially runs the boiler as if it were using an on/off timer. This can produce longer cycle times of say an hour or two which basically uses the slab mass as thermal buffer/storage. In this mode the room temperature fluctuations are modest and barely perceptable: maybe +/- one or two degrees F. Natural gas use is somewhat higher over a 24 hours period, but I don't have exact numbers. The boiler still modulates because of close approach in the primary/secondary heat exchanger. I can probably tune this mode for the same run time over 24 hours as the 2x per hour mode.

My question is whether I should leave the operation as it is with two cycles per hour and save fuel, or should I be optimizing the "timer" mode for the longer run times and be saving the boiler??