Honeywell L4006A,B,E,H Aquastat® Controllers Manual

Honeywell L4006A,B,E,H Aquastat® Controllers Installation Manual

Honeywell L4006A APPLICATION

These boiler-mounted, immersion type controllers operate in response to temperature changes in hydronic heating systems. L4006A breaks the circuit on a temperature rise to the control setting. It is used for high limit or low limit control. When used as a controller or as a low limit, a separate high limit must be used. L4006B makes the circuit on a temperature rise. It is used as a circulator controller, delaying circulator operation when boiler water temperature is below the control setting.

L4006E,H includes a trip-free manual reset switch. These models are designed to break the control circuit whenever the temperature of the controlled medium reaches the high limit setting. A reset button on the front of the case must be pressed to re-establish the control circuit. L4006H also includes bracket and clamp for
surface mounting on pipe or tank. A plastic bag of heat-conductive compound is included with the L4006A,B,E Aquastat® Controllers for use when the sensing bulb is inserted into a well designed for a large bulb than the one used on the L4006A,B,E. A 124904 Well Adapter, for use on old wells that do not fit the L4006A,B,E immersion well clamp, can be ordered; see form 68-0040, Wells and Fittings for Temperature Controllers.. A setting stop is included to prevent setting above a desired temperature on limit. If a well adapter or other accessories are needed, refer to form 68-0040, Wells and Fittings for Temperature Controllers, for part numbers and ordering information.


When Installing This Product…

  1. Read these instructions carefully. Failure to follow them could damage the product or cause a hazardous condition.
  2. Check the ratings given in the instructions and on the product to make sure the product is suitable for your application.
  3. Installer must be a trained, experienced service technician.
  4. After installation is complete, check out product operation as provided in these instructions.

Honeywell L4006A Installing Immersion Well Models (L4006A,B,E)


Obtain the best thermal response with a well that snugly fits the sensing bulb. The bulb should be inserted until it rests against the bottom of the well. Use a well of correct length and bend the tubing, if necessary, to provide enough force to hold the bulb against the bottom of the well. Do not make a sharp bend in the tubing. A sharp bend can produce a break in the tubing and cause a loss of fill. This condition will cause the high and low limit controls to be made continuously.

If the well is not a snug fit on the bulb, use the heat-conductive compound as follows. Fold the plastic bag of compound lengthwise and twist gently. Snip the end of the bag and insert into the well. Slowly pull out the bag while squeezing firmly to distribute the compound evenly in the well. Insert the bulb into the well. Bend the tubing, if necessary, to provide force to hold the bulb against the bottom of the well and to hold the out end of the bulb in firm contact with the side of the well. Wipe off any excess compound.

NOTE: Some models have an adjustable capillary tubing length to 3 inches (76 mm). In these models, pull out extra tubing from inside the case, if needed. Follow the boiler manufacturer instructions, if available; otherwise, proceed as follows.

  1. Remove the old control.
  2. Refer to the cover insert of the old control to identify and tag each lead as it is disconnected.
  3. Leave the old well in place if it is suitable.

If Well is Otherwise Suitable But Does Not Fit The L4006 Immersion Well Clamp

Use a 124904 Well Adapter (order separately, see form 68-0040) to secure the L4006 to the old well. The adapter has a flange at one end for fastening the L4066
adapter clamp.

L4006 Immersion Well Clamp

  1. Loosen, but do not remove, the two adapter clamp screws (see Fig. 1).
  2. Slide the adapter onto the capillary and short tube; see Fig. 2 inset.
  3. Make sure the flanged end of the adapter fits into the hole in the case. Position the adapter well clamp snugly over the flange on the adapter, then tighten the clamp screws.
  4. Insert the bulb into the well, as shown in Fig. 2. If necessary, use the heat-conductive compound as instructed in the IMPORTANT statement on page 1.
  5. Tighten the setscrew (if one is present in the old well spud) against the adapter.

Honeywell L4006A,B,E,H Aquastat® Controllers Manual