Honeywell L8148E Aquastat Issue

jbii24

I just replaced the Aquastat as described above.  It doesn't want to shut the boiler down when it reaches high limit.  I just found that placing a wedge under the limit setting wheel allows the furnace to cycle properly now.  What can I do to in lieu of a wedge that will keep the boiler running as it should?  This is a new problem and started maybe two weeks after installation.

EdTheHeaterMan

That control is defective. Replace it.

Unless you are diagnosing the overtemperature based on a defective thermometer Get a "Known Good" thermometer and actually check the temperature of the boiler water leaving the supply pipe. I use a digital thermometer with a clamp-on thermocouple sensor, but you can use an inexpensive analog dial with some insulation around the probe and the pipe

To celebrate place the sensor in boiling water and the reading should be 212°F (100°C) at sea level, where I am. (adjust for your elevation) and/or place in closely packed ice water and the dial should read 32°F (0°C). Adjust to calibrate accordingly.

now that you know the temperature is accurate then set your control temperature and see if it switches open and closed (on and off) at the proper temperatures.

I believe the control is defective. That is my gut feeling

Mr. Ed

EdTheHeaterMan

Are the wires on the correct terminals?
Take a picture of the wires inside the control and one from farther away.