whereas the "NSA" version utilizes a standard terminal block for field-wired connections

providing essential safety interlocking to prevent equipment operation during low-pressure conditions

The "nozzle and flapper" pilot mechanism delivers high sensitivity and linearity

60 Hz with an amperage rating of approximately 1

This is often caused by a cracked heat exchanger

Resideo L6006A1244 Aquastat Controller 321702-401 whereas the "NSA" version utilizesThe Resideo L6006A1244 Aquastat Controller is a high performance immersion temperature controller engineered for precise regulation of liquids in boilers and storage tanks. Featuring SPDT switching action, this versatile unit functions as a high limit, low limit, or circulator control, ensuring reliable system operation under varying thermal loads. The controller utilizes a 3 8" x 2 7 8" copper bulb connected via a 3" capillary for accurate sensing.