Resideo Aquastat Relay, 180 to 240 F Range with 15 Degree F Fixed Differential, Low Volt/Millivolt L8148E1299/U

Item #: HONE-L8148E1299/U
Mfr. part #: L8148E1299/U
UPC: 085267163668

Key specifications

High limit180-240 °F
Differential15 °F fixed
SwitchingSPST limit + circ.
Transformer50 VA included
MountingVertical

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$382.97

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Shipping details

Shipping weight: 4.0 lb
Box size: 7.3 × 5.4 × 5.15 in

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Brand	Resideo
Manufacturer part #	L8148E1299/U
Voltage	120 Vac
Frequency	60 Hz
Electrical Connections	Quick-Connect / Screw
Electrical Ratings	Low Voltage: 0.8 A max. @ 24 Vac; 0.25 A @ 0.25 to 12 Vdc; At Locked Rotor-- 44.4A @ 120 Vac: 22.2A @ 240 Vac
Operating Temperature	High Limit-- 180 F to 240 F
Operating Humidity	0 to 95% RH, non-condensing
Mounting	Vertical Mount
Application	High Limit
Includes	50 VA transformer and heat conductive compound.
Dimensions	6 1/8 in. high x 4 5/16 in. wide x 3 1/8 in. deep
UL	UL Listed: File No. MP466, Vol. 13, Sec. 2, Guide No. MBPR2.
CSA	Certified: File No. LR95329-1
Hazmat Information	Dangerous Goods in Excepted Quantities
Maximum Safe Operating Pressure (psi)	Immersion Well: 255 psi
Temperature Range (F)	Maximum--150 F with 1.2 A 24 V load; 77 F with 1.4 A 24 V load
Differential Temperature (F)	15 F fixed
Switching Action	SPST: High Limit & Circulator
Anticipator Setting	0.2 A
Capillary Length (in.)	4 1/2 in.
Insulation Depth (in.)	1 1/2 in. to 3 in. less well
Electrical Ratings, Burner	At Full Load-- Low Voltage: 0.8 A max. @ 24 Vac: Line Voltage: 7.4 A @ 120 Vac: 3.7 A @ 240 Vac; At Locked Rotor-- Line Voltage: 44.4 A @ 120 Vac: 22.7 A @ 240 Vac
Electrical Ratings, Circulator	At Full Load-- 7.4 A @ 120 Vac: 3.7 A @ 240 Vac; At Locked Rotor-- 44.4 A @ 120 Vac: 22.2 A @ 240 Vac
UPC	085267163668

The L8148E1299 is a relay from Resideo (Honeywell Home) that senses boiler water temperature and switches the burner, the circulator, or both. It operates over a 180–240 °F range with a fixed 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 differential is factory fixed, which removes one setting from the commissioning process and one thing for a future service call to get wrong.

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.