Dual Power Non-Programmable Thermostat, Horizontal Mount (1 Heat - 1 Cool)

This was answer to my boiler problem. I installed a new Weil McClain hot water house radiator heating boiler (CGI-6). This was slightly oversized, since I could not get one with the same BTU output as the old boiler. The old Honeywell thermostat with the mercury switch and anticipator did not work properly with the new boiler, so I needed a new thermostat. Per recommendation by the manufacturer, I first tried a Honeywell replacement for the old mercury type. However, it is not an exact representation-- the new type does not have a continuous analog anticipator (heating coil) -- it only has four digital settings by switches for 1, 3, 5, 9 cycles per hour. For boilers it recommends 3 CPH. This did not work well for my system -- was OK when outside temp was below ~40 deg F, but when temp was above ~40 deg F, the boiler return water was only 110-120 deg F, below required 130 deg F (minimum to prevent condensation without a crossover pipe - see manual). I then tried 1 CPH -- OK when outside temp was above ~30 deg F, but when temp was below ~25 deg F, the unit defaulted to a swing temp range of ~2 deg F. This caused the boiler to heat up until the upper boiler temp setting was reached (170 deg), then cooled to 150 deg F (boiler has a fixed 20 deg swing) and turned on again -- this cycle repeated 4-7 times until the temperature reached the defaulted thermostat swing. The house temperature was then too hot and took 1-2 ours to cool down until the thermostat turned on again. This stressed the boiler by cycling more than needed and overheating the house. This LUX unit uses a temperature swing settings in 0.25 deg F steps and 12 step settings. I used the 0.25 deg F setting, and now the house temperature stays within 1 deg F. The boiler cycles only once per hour most of the time -- when very cold (or starting from a low temperature, it will run up to the maximum boiler temp then cycle only 2 times to reach cut off. It uses 2 AA batteries so a once per year replacement.