ResideoSKU: 37976

Resideo L4006A1959/U Breaks on Rise Aquastat Controller

$187.21
In stock (15)

The L4006A1959/U is an immersion-type Aquastat controller for limiting or regulating liquid temperature in boilers, storage tanks, and hydronic heating applications. Provides SPST switching that breaks on temperature rise at the setpoint — suitable for high limit or low limit control. Operating range 40-180F with 5F fixed differential; horizontal or vertical immersion well mount; 3 in. insulation depth; shipped less well. Sensing bulb: 3/8 x 2-7/8 in. copper. Screw terminal wiring. Requires professional installation by a licensed HVAC or plumbing technician.

Shipping policy

Orders placed by 2:00pm EST will ship same day, except on holidays.

More Details

Product overview
  • SPST switching — breaks circuit on temperature rise at setpoint; suitable for high or low limit control
  • Operating range: 40-180F with 5F fixed differential
  • Vertical or horizontal mount; shipped less well — specify boiler tapping size (1/2 or 3/4 in. NPT) when ordering well separately
  • Insulation depth: 3 in.
  • Sensing bulb: 3/8 x 2-7/8 in. copper; liquid fill (toluene or silicone oil)
  • Maximum operating pressure: 200 psi (direct immersion); 255 psi (immersion well)
  • Totally enclosed Micro Switch snap-acting switch
  • Screw terminal wiring; maximum ambient temperature: 150F
  • UL Component Recognized: File No. MP466, Guide No. MBPR2
Specifications
Manufacturer Part Number L4006A1959/U
UPC 85267048682
Overall Dimensions 5-1/8 in W x 1-1/8 in D x 3-13/16 in H
Material n/a
Domestic or Import n/a
End Style n/a
Type Breaks on Rise
ADA Compliance n/a
Warning Professional installation required
Standards and Approvals AGA Certified | CSA File No LR95329-1 | Guide No MBPR2 | UL File No MP466
Resources
Delivery & Returns

Orders will ship same day if received by 2pm EST.

Upcoming holiday closures: May 25, 2026

All returns are inspected on receipt; credit is issued after condition is confirmed. Credit is issued only for items returned in original, saleable condition after inspection.

FINAL SALE ITEMS ARE NOT ELIGIBLE FOR RETURNS OR EXCHANGES.

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