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Differential

Adjustable (33)
Fixed (22)
Manual Reset (12)

Switch Action

Contacts Break on Temp Rise (27)
Open on Rise (3)
SPDT (8)
SPST (39)

Min Temp (F)

100°F (1)
40°F (1)
65°F (1)
95°F (1)
100°F (27)
110°F (10)
120°F (2)
130°F (9)
180°F (2)

Max Temp (F)

115°F (1)
135°F (1)
180°F (2)
200°F (5)
220°F (1)
240°F (37)
240°F (1)
270°F (7)
270°F (1)

Application

Accessory (11)
Circulator Control (16)
High Limit (48)
Low Limit (21)
Oil Aquastat Controller (1)
Strap-On (4)
Triple Aquastat Relay (5)

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(61)
(5)
(2)

Price Range

$15 to $20 (3)
$30 to $35 (1)
$35 to $40 (1)
$40 to $45 (4)
$45 to $50 (2)
$50 to $60 (9)
$60 to $70 (3)
$70 to $80 (1)
$80 to $90 (2)
$100 to $200 (21)

Boiler Aquastats

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Product Image of High Limit Vertical Mount Aquastat Relay, 15-Degree (F) Differential, L8148E1265
$376.06 each
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Product Image of High or Low Limit & Circulator Strap-On Aquastat, 65-200-Degree(F) range, 5-30-Degree(F) Adj Differential, L6006C1018
$166.64 each
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Product Image of 120 Vac Oil Electronic Aquastat, L7224U1002
120 Vac Oil Electronic Aquastat, L7224U1002
SKU: L7224U1002
Resideo
SKU: L7224U1002
Brand: Resideo
(49)
$241.84 each
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Product Image of High Limit Horizontal Mount Aquastat Relay, 8-Degree(F) differential, L8148A1017
$280.87 each
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Product Image of High or Low Limit Aquastat, 100-240-Degree(F) range, 5-30-Degree(F) Adj Differential, L4006A2007
$154.80 each
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Product Image of High Limit Immersion Aquastat, 100-200-Degree (F) Range, L4080B1352
$88.81 each
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Product Image of 3/4" Aquastat Well
3/4" Aquastat Well
SKU: 121371B-OMI
OMI Parts
SKU: 121371B-OMI
Brand: OMI Parts
(1)
$18.75 each
In Stock
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Product Image of High Limit, Manual Aquastat Controller w/ 130-Degree(F) to 270-Degree(F) Operating Temp, L4006E1000
$146.90 each
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Product Image of High Limit Strap-On Aquastat, 100-240-Degree (F) range, Manual Reset, L4006H1004
$266.73 each
In Stock
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Product Image of Aquastat Relay, 8-Degree(F) Differential, L8148J1009
Aquastat Relay, 8-Degree(F) Differential, L8148J1009
SKU: L8148J1009
Resideo
SKU: L8148J1009
Brand: Resideo
(72)
$345.67 each
In Stock
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Product Image of 1/2" Aquastat Well
1/2" Aquastat Well
SKU: 121371A-OMI
OMI Parts
SKU: 121371A-OMI
Brand: OMI Parts
(7)
$16.33 each
In Stock
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Product Image of High or Low Limit & Circulator, Horizontal Mount Aquastat, 100-240-Degree(F) range, 5-30-Degree(F) Adj Differential, L6006A1145
$185.36 each
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Product Image of High or Low Limit Remote Bulb Aquastat, 100-240-Degree (F), 5-30-Degree (F) Adj Differential, L4008A1015
$188.67 each
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Product Image of High Limit, Manual Reset Aquastat Controller w/ 130-Degree (F) to 270-Degree (F) Operating Temp, L4008E1040
$162.21 each
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Product Image of 3/4" Aquastat Well, 121371B
3/4" Aquastat Well, 121371B
SKU: 121371B
Resideo
SKU: 121371B
Brand: Resideo
(19)
$51.24 each
In Stock
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Product Image of High Limit Protection, Low Limit & Circulator Triple Aquastat Relay, High = 10-Degree(F), Low Limit = 10-25-Degree Adj Differential, L8124A1007
$373.74 each
In Stock
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Product Image of Temperature Aquastat for "00" Series Circulators (95°F  - 115°F )
$63.82 each
In Stock
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Product Image of High Limit Vertical Mount Aquastat Relay, 15-Degree(F) differential w/ 50VA Transformer, L8148E1299
$366.49 each
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Product Image of 1/2" Aquastat Well, 121371A
1/2" Aquastat Well, 121371A
SKU: 121371A
Resideo
SKU: 121371A
Brand: Resideo
(19)
$45.00 each
In Stock
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Product Image of High or Low Limit Aquastat, 40-Degree(F) to 180-Degree(F) Range, L4006A1959
$175.79 each
In Stock
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Product Image of 3/4" Long Aquastat Well, 121371M
3/4" Long Aquastat Well, 121371M
SKU: 121371M
Resideo
SKU: 121371M
Brand: Resideo
(1)
$67.51 each
In Stock
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Product Image of High or Low Limit Aquastat, 100-240-Degree(F) range, 5-Degree(F) to 30-Degree(F) Differential, L4006A1678
$176.43 each
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Product Image of High or Low Limit Aquastat, 100-240-Degree(F) range, 5-30-Degree(F) Adj Differential, L4006A1967
$185.97 each
In Stock
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Product Image of High Limit Horizontal Mount Triple Aquastat Relay, High = 10-Degree(F) Diff, Low Limit = 10-25-Degree Adj Differential, L8124C1003
$377.34 each
In Stock
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Product Image of 3/4" Aquastat Well (3" Long), 123871A
3/4" Aquastat Well (3" Long), 123871A
SKU: 123871A
Resideo
SKU: 123871A
Brand: Resideo
(1)
$63.90 each
In Stock
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Product Image of High Limit Aquastat, 130-270-Degree (F) range, Manual Reset, L4006E1067
$257.23 each
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Product Image of High or Low Limit & Circulator Aquastat, 100 - 240-Degree(F) Range, 5 - 30-Degree(F) Adj Differential, L6006A1244
$175.39 each
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Product Image of High & Low Limit Aquastat, High = 10°F Diff, Low = 10-25-Degree Adj Differential, L4081A1023
$314.50 each
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Product Image of Surface Mount Hydronic Temperature Control (Strap-On)
$169.90 each
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Product Image of Well Immersion Control w/ 100-240°F and Adjustable Differential (Open On Rise)
$149.26 each
Out of Stock
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Product Image of Circulator Aquastat, 100-240-Degree(F) range, 5-30-Degree(F) Adj Differential, L4006B1163
$157.36 each
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Product Image of High Limit Remote Bulb Aquastat, 100-240-Degree (F) range, Manual Reset, L4008E1305
$273.46 each
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Product Image of High Limit Remote Bulb Aquastat, 100-200-Degree (F) Range, Manual Reset, L4008E1313
$252.50 each
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Product Image of High Limit Remote Bulb Aquastat, 130-270-Degree (F) range, Manual Reset, L4008E1156
$233.73 each
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Product Image of High Limit, Manual Reset Aquastat Controller w/ 100-Degree (F) to 240-Degree (F) Operating Temp, L4006E1117
$297.13 each
In Stock
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Product Image of Sensor Assembly w/ 12" Leads, 50001464-001
Sensor Assembly w/ 12" Leads, 50001464-001
SKU: 50001464-001
Resideo
SKU: 50001464-001
Brand: Resideo
(4)
$43.81 each
In Stock
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Product Image of 7-Day Digital Timer (120V)
7-Day Digital Timer (120V)
SKU: 265-DT
Taco
SKU: 265-DT
Brand: Taco
$80.53 each
In Stock
Get 16 by Tue, Jun 9
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Product Image of Well Clamp Assembly, 121371AA
Well Clamp Assembly, 121371AA
SKU: 121371AA
Resideo
SKU: 121371AA
Brand: Resideo
(1)
$17.71 each
In Stock
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Product Image of 24 Hour Analog Timer w/ Dust Cover
24 Hour Analog Timer w/ Dust Cover
SKU: 265-1
Taco
SKU: 265-1
Brand: Taco
(4)
$178.03 each
In Stock
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Product Image of High Limit Triple Vertical Mount Aquastat Relay, High = 10-Degree(F) Diff, Low = 10-25-Degree(F) Adj Differential, L8124E1016
$412.33 each
In Stock
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Product Image of 1/2" Long Aquastat Well, 121371L
1/2" Long Aquastat Well, 121371L
SKU: 121371L
Resideo
SKU: 121371L
Brand: Resideo
(1)
$59.81 each
In Stock
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Product Image of Circulator Remote Bulb Aquastat, 100-240-Degree (F), 5-30-Degree (F) Adj Differential, L4008B1013
$205.31 each
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Product Image of Flush Mount Sensor Assembly w/ 48" Lead, 50001464-005
Flush Mount Sensor Assembly w/ 48" Lead, 50001464-005
SKU: 50001464-005
Resideo
SKU: 50001464-005
Brand: Resideo
(3)
$42.39 each
In Stock
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Product Image of High or Low Limit Aquastat, 100-240-Degree(F) range, 5-30-Degree(F) Adj Differential, L4006A1017
$239.27 each
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Product Image of High Limit Protection, Low Limit & Circulator Vertical Mount Triple Aquastat Relay, High=10-Degree(F), Low Limit=10-25-Degree Adj Differential, L8124A1015
$377.34 each
In Stock
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Product Image of Well Immersion Control w/ 100-240°F Range and 7-45°F Differential
$192.35 each
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Product Image of High or Low Limit Aquastat, 100-240-Degree(F) range, 5-Degree(F) Differential, L4006A1009
$220.96 each
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Product Image of High Limit Aquastat Controller, 100-180-Degree(F) Range, 5-Degree(F) Differential, L8100B1128
$365.60 each
In Stock
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Resources
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Articles
More About Aquastats & Wells
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.