Resideo L4006A1967/U Aquastat, Breaks on Rise, 100-240F Range, 240F Factory Stop, 5-30F Adjustable Differential

Item #: HONE-L4006A1967/U
Mfr. part #: L4006A1967/U
UPC: 085267048699

Key specifications

MountingHorizontal or Vertical
Operating Temperat100 F to 240 F
AGAAGA Certified
Temperature RangeMaximum--150 F
Bulb Size3/8 in. x 2 7/8 in. copper

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$198.06

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Shipping details

Shipping weight: 1.4 lb
Box size: 12.6 × 5.3 × 2.35 in

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Brand	Resideo
Manufacturer part #	L4006A1967/U
Electrical Ratings	Millivolt--0.25 A @ 0.25 to 12 Vdc; At Full Load-- 8A @ 120 Vac: 5.1A @ 240 Vac; At Locked Rotor-- 48A @ 120 Vac: 30.6A @ 240 Vac
Operating Temperature	100 F to 240 F
Mounting	Horizontal or Vertical
Application	High or Low limit
Includes	1/2 in. well - 123869A; Stop factory-set at 240 F (116 C)
Dimensions	Case--5 5/8 in. high x 2 in. wide x 2 1/8 in. deep
UL	UL Component Recognized: File No. MP466, Vol. 6, Sec.1, Guide No. MBPR2
CSA	Certified: File No. LR95329-1
AGA	AGA Certified
Hazmat Information	Dangerous Goods in Excepted Quantities
Temperature Range (F)	Maximum--150 F
Bulb Size (in.)	3/8 in. x 2 7/8 in. copper
Differential Temperature (F)	5 F to 30 F adj.
Switching Action	SPST, contacts break on temperature rise.
Capillary Length (in.)	1 1/2 in.
Well Spud Size (in.)	1/2 in.
UPC	085267048699

The L4006A1967 is a control from Resideo (Honeywell Home) that senses boiler water temperature and switches the burner, the circulator, or both. It operates over a 100–240 °F range with an adjustable differential.

The aquastat is the control that keeps a hydronic boiler inside its working band. It holds the water hot enough to serve a call for heat and shuts the burner down before the boiler reaches a temperature the relief valve would have to handle.

The adjustable differential sets how far the water has to cool before the burner is allowed to fire again. A wide differential means longer, less frequent burns; a narrow one holds temperature tighter at the cost of more cycling.

A factory stop at 240 °F caps the adjustment so the high limit cannot be set past the point the boiler is rated for.

When you replace an aquastat, match the temperature range, the switch action and the differential to the control coming out, not to the boiler nameplate. A boiler will happily run on a control with the wrong range — it will simply cycle badly, or trip a limit that was never meant to be the working control.

The sensing bulb belongs in an immersion well, filled with heat conductive compound, threaded into the tapping the boiler manufacturer provided for it. A bulb strapped to the outside of a pipe reads the pipe, not the water, and it reads it late.