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  • High Limit Vertical Mount Aquastat Relay<br>15°F Differential Product Image
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    High Limit Vertical Mount Aquastat Relay 15°F Differential L8148E1265 High Limit Vertical Mount Aquastat Relay 15°F Differential
    SKU: L8148E1265 Resideo
    SKU: L8148E1265
    Brand: Resideo
    (98)
    $254.71 each
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    230
    Mon, Feb 7
    230
    QtyArrives
    230 Mon, Feb 7
    Questions? Call 1-888-757-4774
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  • High or Low Limit & Circulator Strap-On Aquastat, 65°F to 200°F Product Image
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    High or Low Limit & Circulator Strap-On Aquastat, 65°F to 200°F L6006C1018 High or Low Limit & Circulator Strap-On Aquastat, 65°F to 200°F
    SKU: L6006C1018 Resideo
    SKU: L6006C1018
    Brand: Resideo
    (42)
    $114.10 each
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    150
    Mon, Feb 7
    150
    QtyArrives
    150 Mon, Feb 7
    Questions? Call 1-888-757-4774
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  • High Limit Horiz. Mount Aquastat Relay<br>8°F Differential Product Image
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    High Limit Horiz. Mount Aquastat Relay 8°F Differential L8148A1017 High Limit Horiz. Mount Aquastat Relay 8°F Differential
    SKU: L8148A1017 Resideo
    SKU: L8148A1017
    Brand: Resideo
    (86)
    $189.83 each
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    444
    Mon, Feb 7
    444
    QtyArrives
    444 Mon, Feb 7
    Questions? Call 1-888-757-4774
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  • 120 Vac Oil<br>Electronic Aquastat Product Image
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    120 Vac Oil Electronic Aquastat L7224U1002 120 Vac Oil Electronic Aquastat
    SKU: L7224U1002 Resideo
    SKU: L7224U1002
    Brand: Resideo
    (41)
    $179.07 each
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    Fri, Apr 15 – Fri, May 13
    Arrives
    Fri, Apr 15 – Fri, May 13
    Questions? Call 1-888-757-4774 or
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  • High or Low Limit Aquastat 100-240°F Range<br>5-30°F Adj Differential Product Image
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    High or Low Limit Aquastat 100-240°F Range 5-30°F Adj Differential L4006A2007 High or Low Limit Aquastat 100-240°F Range 5-30°F Adj Differential
    SKU: L4006A2007 Resideo
    SKU: L4006A2007
    Brand: Resideo
    (17)
    $108.97 each
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    Added to List Icon List
    519
    Mon, Feb 7
    519
    QtyArrives
    519 Mon, Feb 7
    Questions? Call 1-888-757-4774
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  • 140-240F AquaStat Relay w/ Vent Damper Connection Product Image
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    140-240F AquaStat Relay w/ Vent Damper Connection L8148E1257 140-240F AquaStat Relay w/ Vent Damper Connection
    SKU: L8148E1257 Resideo
    SKU: L8148E1257
    Brand: Resideo
    (62)
    $271.40 each
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    Fri, Feb 18 – Fri, Feb 25
    Arrives
    Fri, Feb 18 – Fri, Feb 25
    Questions? Call 1-888-757-4774 or
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  • Aquastat Relay<br>8°F Differential Product Image
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    Aquastat Relay 8°F Differential L8148J1009 Aquastat Relay 8°F Differential
    SKU: L8148J1009 Resideo
    SKU: L8148J1009
    Brand: Resideo
    (58)
    $239.13 each
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    Added to List Icon List
    283
    Mon, Feb 7
    283
    QtyArrives
    283 Mon, Feb 7
    Questions? Call 1-888-757-4774
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  • High Limit Immersion Aquastat, 100-200&deg;F Range, 8&deg;F Differential Product Image
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    High Limit Immersion Aquastat, 100-200°F Range, 8°F Differential L4080B1352 High Limit Immersion Aquastat, 100-200°F Range, 8°F Differential
    SKU: L4080B1352 Resideo
    SKU: L4080B1352
    Brand: Resideo
    (6)
    $68.94 each
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    Added to List Icon List
    340
    Mon, Feb 7
    340
    QtyArrives
    340 Mon, Feb 7
    Questions? Call 1-888-757-4774
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  • High Limit Protection<br>Low Limit & Circulator Triple Aquastat Relay Product Image
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    High Limit Protection Low Limit & Circulator Triple Aquastat Relay L8124A1007 High Limit Protection Low Limit & Circulator Triple Aquastat Relay
    SKU: L8124A1007 Resideo
    SKU: L8124A1007
    Brand: Resideo
    (25)
    $251.15 each
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    Added to List Icon List
    196
    Mon, Feb 7
    196
    QtyArrives
    196 Mon, Feb 7
    Questions? Call 1-888-757-4774
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  • High/Low Limit Circulator Horiz. Mount Aquastat<br>100-240°F Product Image
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    High/Low Limit Circulator Horiz. Mount Aquastat 100-240°F L6006A1145 High/Low Limit Circulator Horiz. Mount Aquastat 100-240°F
    SKU: L6006A1145 Resideo
    SKU: L6006A1145
    Brand: Resideo
    (23)
    $126.77 each
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    Added to List Icon List
    102
    Mon, Feb 7
    102
    QtyArrives
    102 Mon, Feb 7
    Questions? Call 1-888-757-4774
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  • 3/4" Aquastat Well Product Image
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    3/4" Aquastat Well 121371B 3/4" Aquastat Well
    SKU: 121371B Resideo
    SKU: 121371B
    Brand: Resideo
    (18)
    $34.59 each
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    Added to List Icon List
    548
    Mon, Feb 7
    548
    QtyArrives
    548 Mon, Feb 7
    Questions? Call 1-888-757-4774
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  • 1/2" Aquastat Well Product Image
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    1/2" Aquastat Well 121371A 1/2" Aquastat Well
    SKU: 121371A Resideo
    SKU: 121371A
    Brand: Resideo
    (18)
    $32.01 each
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    Added to List Icon List
    964
    Mon, Feb 7
    964
    QtyArrives
    964 Mon, Feb 7
    Questions? Call 1-888-757-4774
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  • 3/4" Aquastat Well Product Image
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    3/4" Aquastat Well 121371B-OMI 3/4" Aquastat Well
    SKU: 121371B-OMI OMI
    SKU: 121371B-OMI
    Brand: OMI
    (1)
    $16.20 each
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    Added to List Icon List
    361
    Mon, Feb 7
    361
    QtyArrives
    361 Mon, Feb 7
    Questions? Call 1-888-757-4774
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  • High Limit Strap-On Aquastat, Manual Reset 100°F to 240°F Product Image
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    High Limit Strap-On Aquastat, Manual Reset 100°F to 240°F L4006H1004 High Limit Strap-On Aquastat, Manual Reset 100°F to 240°F
    SKU: L4006H1004 Resideo
    SKU: L4006H1004
    Brand: Resideo
    (7)
    $192.41 each
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    Added to List Icon List
    413
    Mon, Feb 7
    413
    QtyArrives
    413 Mon, Feb 7
    Questions? Call 1-888-757-4774
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  • Temperature Aquastat for "00" Series Circulators (95&#176;F to 115&#176;F) Product Image
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    Temperature Aquastat for "00" Series Circulators (95°F to 115°F) 563-2 Temperature Aquastat for "00" Series Circulators (95°F to 115°F)
    SKU: 563-2 Taco
    SKU: 563-2
    Brand: Taco
    (4)
    $34.96 each
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    59
    Mon, Feb 7
    101
    QtyArrives
    59 Mon, Feb 7
    42 Tue, Feb 8 – Wed, Feb 9
    Questions? Call 1-888-757-4774
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  • High or Low Limit Remote Bulb Aquastat, 100-240°F<br>5-30°F Adj. Differential Product Image
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    High or Low Limit Remote Bulb Aquastat, 100-240°F 5-30°F Adj. Differential L4008A1015 High or Low Limit Remote Bulb Aquastat, 100-240°F 5-30°F Adj. Differential
    SKU: L4008A1015 Resideo
    SKU: L4008A1015
    Brand: Resideo
    (13)
    $139.01 each
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    Added to List Icon List
    12
    Mon, Feb 7
    12
    QtyArrives
    12 Mon, Feb 7
    Questions? Call 1-888-757-4774
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  • High/Low Limit Aquastat<br>40&#176;F to 180&#176;F Range Product Image
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    High/Low Limit Aquastat 40°F to 180°F Range L4006A1959 High/Low Limit Aquastat 40°F to 180°F Range
    SKU: L4006A1959 Resideo
    SKU: L4006A1959
    Brand: Resideo
    (9)
    $129.00 each
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    Added to List Icon List
    204
    Mon, Feb 7
    204
    QtyArrives
    204 Mon, Feb 7
    Questions? Call 1-888-757-4774
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  • High Limit, Manual Aquastat Controller<br>130°F to 270°F Product Image
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    High Limit, Manual Aquastat Controller 130°F to 270°F L4006E1000 High Limit, Manual Aquastat Controller 130°F to 270°F
    SKU: L4006E1000 Resideo
    SKU: L4006E1000
    Brand: Resideo
    (3)
    $121.10 each
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    Added to List Icon List
    251
    Mon, Feb 7
    251
    QtyArrives
    251 Mon, Feb 7
    Questions? Call 1-888-757-4774
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  • 1/2" Aquastat Well Product Image
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    1/2" Aquastat Well 121371A-OMI 1/2" Aquastat Well
    SKU: 121371A-OMI OMI
    SKU: 121371A-OMI
    Brand: OMI
    (4)
    $13.00 each
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    Added to List Icon List
    408
    Mon, Feb 7
    408
    QtyArrives
    408 Mon, Feb 7
    Questions? Call 1-888-757-4774
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  • High Limit Vertical Mount Aquastat Relay<br>15°F Differential Product Image
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    High Limit Vertical Mount Aquastat Relay 15°F Differential L8148E1299 High Limit Vertical Mount Aquastat Relay 15°F Differential
    SKU: L8148E1299 Resideo
    SKU: L8148E1299
    Brand: Resideo
    (17)
    $261.38 each
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    Added to List Icon List
    108
    Mon, Feb 7
    108
    QtyArrives
    108 Mon, Feb 7
    Questions? Call 1-888-757-4774
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  • High or Low Limit Aquastat 100-240°F Range<br>5-30°F Adj Differential Product Image
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    High or Low Limit Aquastat 100-240°F Range 5-30°F Adj Differential L4006A1967 High or Low Limit Aquastat 100-240°F Range 5-30°F Adj Differential
    SKU: L4006A1967 Resideo
    SKU: L4006A1967
    Brand: Resideo
    (7)
    $131.24 each
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    Added to List Icon List
    193
    Mon, Feb 7
    193
    QtyArrives
    193 Mon, Feb 7
    Questions? Call 1-888-757-4774
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  • High Limit, Manual Reset Aquastat Controller<br>130&#176;F to 270&#176;F Product Image
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    High Limit, Manual Reset Aquastat Controller 130°F to 270°F L4008E1040 High Limit, Manual Reset Aquastat Controller 130°F to 270°F
    SKU: L4008E1040 Resideo
    SKU: L4008E1040
    Brand: Resideo
    (1)
    $123.45 each
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    Added to List Icon List
    69
    Mon, Feb 7
    69
    QtyArrives
    69 Mon, Feb 7
    Questions? Call 1-888-757-4774
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  • High Limit Horiz. Mount Triple Aquastat Relay Product Image
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    High Limit Horiz. Mount Triple Aquastat Relay L8124C1003 High Limit Horiz. Mount Triple Aquastat Relay
    SKU: L8124C1003 Resideo
    SKU: L8124C1003
    Brand: Resideo
    (16)
    $260.94 each
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    Added to List Icon List
    61
    Mon, Feb 7
    61
    QtyArrives
    61 Mon, Feb 7
    Questions? Call 1-888-757-4774
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  • High Limit Aquastat<br>130°F to 270°F Range<br>Manual Reset Product Image
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    High Limit Aquastat 130°F to 270°F Range Manual Reset L4006E1067 High Limit Aquastat 130°F to 270°F Range Manual Reset
    SKU: L4006E1067 Resideo
    SKU: L4006E1067
    Brand: Resideo
    (5)
    $176.17 each
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    Added to List Icon List
    122
    Mon, Feb 7
    122
    QtyArrives
    122 Mon, Feb 7
    Questions? Call 1-888-757-4774
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FAQs, Manuals & Videos

Resources

Videos

Articles

  • An aquastat is a device used to control water temperature in hydronic heating systems. It has both high and low limit temperature controls to prevent boilers from firing too frequently. Aquastats are a type of thermostat that senses the temperature of the water and activates or deactivates the burner by controlling the electrical circuit. The temperature of the water is maintained by the aquastat within its preset limits. When the thermostat demands heat, the heating mechanism activates and heat will be sent until the maximum temperature limit is reached. At that point, the mechanism will turn off. If the boiler's water temperature drops below the max temperature limit, the boiler will re-fire. The boiler will also re-fire when the boiler water temperature goes below a range around the low limit. This low limit is intended for tankless domestic hot water, ensuring that boiler water remains warm enough to heat domestic hot water.

    Aquastat wells are used in conjunction with aquastats. Immersion wells are used with Aquastat Temperature Controllers to hold the temperature sensing bulb in the controlled medium. They also prevent leakage of the controlled medium. Honeywell aquastat wells are popular and are available in 1/2" and 3/4" sizes.

    Our website offers a wide selection of Honeywell, White Rodgers, and Taco aquastats and wells for regulating the temperature of liquids in boilers, storage tanks, and other applications where temperature control is required.
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