Bought a new-to-me house recently, built in 1953, and has the original boiler for the single-zone radiant heating system. Not the most efficient piece around, but it works just fine. A few times in the last 2 days though, the temperature limit switch for the boiler chamber has popped. This limit switch is in series with the aquastat and has a sensing tube going into the boiler chamber itself. It has an old tridicator gauge, showing system pressure at 18 psi and water temp hovers around 155/160 degrees. Aquastat only has a high setting (no low limit adjustment), and is set to 160, so that seems to be working just fine. I noticed yesterday that the aquastat shut off the boiler when the water reached 160, and then a few seconds after, the boiler limit switch tripped and wouldn't let me reset for about 30 seconds. What seems to be up here? Is my limit switch going bad? Forgive me if I sound uninformed, because I am when it comes to boilers. System has a little bit of air, as I can hear some sloshing in the pipes, FWIW. But water IS being circulated to every room. I should add that it's been warmer here the past few days, so the boiler isn't working as hard as it was earlier in the winter. One thing that may/may not be related is that it appears that 160 is quite a low temperature setting for home heating boilers, from what my research has told me. I haven't touched it since we moved here; maybe it needs to be adjusted.