[Half-Inch Stud]

So we have really enjoyed our Cast Iron Radiator heat. Mysteriously comfortable up until this past week. Then not so good; Bedroom too hot while House being held at 70F on the Main Floor. Dry like desert tortoise, and 1-sheet was a plenty.

Well today i inspected the 1950s gas furnace and found it running the water to 225F and 25 PSI. !!!! Instinctively went into it and found the Water Jacket Mercury Switch had Sprung to that high setting due to the Lock tension Thumbscrew losing tightness. Well i rotated the Jacket Temp setting down until it ckicked off. That was 150F. So locked it tight.

Turns out the Furnace resorted to the emergency trip circuit (another thermo switch in the Furnace set an apparent 225F or higher) for cycling the gas on/off. PHEW; averted a calamity.

Sits and thinks; what does the Internet say? "140-170F" on many blogs. Okaaay. So this is a PSA to check your Circulating Water Temp, and also keep the PSI safe too.