L4006A,B,E,H AQUASTAT® CONTROLLERS
For proper selections of settings, follow boiler
1. High limit controller: Shuts off burner when water
temperature exceeds high limit setting. Burner
restarts when temperature drops to high limit setting
minus the temperature differential.
NOTE: If L4006E or H, see Manual Reset section.
2. Low limit controller: Maintains minimum boiler tem-
perature for domestic hot water. Turns boiler on at
temperature setting, less differential.
3. Circulator controller: Prevents circulation of water
that is not hot enough. Breaks circulator circuit at
temperature setting minus differential and remakes
Set the differential to correspond with the boiler
manufacturer recommendations. To adjust models with
adjustable differential, rotate the wheel on the back of the
snap switch until the desired reading is aligned with the V
notch in the frame. The wheel provides an adjustment
from 5°F to 30°F (3°C to 17°C). Replace the cover on the
Adjust the control point to correspond with the boiler
manufacturer recommendations. To adjust, insert a
screwdriver in the slotted screw type head located
beneath the window in the cover. Turn the scale to the
desired control point.
When the device includes manual reset (L4006E and H),
be sure to press the red reset button on the front of the
case to make sure that the controller is not locked out on
safety. When checking out the system, adjust the control
point low enough so the temperature of the controlled
medium reaches the high limit setting, the burner shuts
off, and the Aquastat Controller locks out. When the
temperature of the controlled medium drops to the high
limit setting minus differential, push the manual reset
button and the system should be operative again. Reset
control to proper high limit setting.
Check to make certain that the Aquastat Controller has
been installed and adjusted properly. Put the system into
operation and observe the action of the device through
several cycles to make certain that it provides proper
control of the system as described in the Operations
section. Further adjustments can be made to meet more
exact comfort requirements.