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  • 1 Zone Switching Relay Product Image
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    1 Zone Switching Relay SR501-4 1 Zone Switching Relay
    SKU: SR501-4
    Brand: Taco
    (123)
    $60.00 each
    538
    Mon, Nov 9
    1,250
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    538 Mon, Nov 9
    712 Wed, Nov 11 – Thu, Nov 12
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  • 2 Zone Switching Relay Product Image
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    2 Zone Switching Relay SR502-4 2 Zone Switching Relay
    SKU: SR502-4
    Brand: Taco
    (22)
    $142.00 each
    297
    Mon, Nov 9
    693
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    297 Mon, Nov 9
    396 Wed, Nov 11 – Thu, Nov 12
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  • 3 Zone Switching Relay Product Image
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    3 Zone Switching Relay SR503-4 3 Zone Switching Relay
    SKU: SR503-4
    Brand: Taco
    (39)
    $150.00 each
    333
    Mon, Nov 9
    942
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    333 Mon, Nov 9
    609 Wed, Nov 11 – Thu, Nov 12
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  • 4 Zone Switching Relay Product Image
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    4 Zone Switching Relay SR504-4 4 Zone Switching Relay
    SKU: SR504-4
    Brand: Taco
    (123)
    $182.00 each
    246
    Mon, Nov 9
    614
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    246 Mon, Nov 9
    368 Wed, Nov 11 – Thu, Nov 12
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  • 6 Zone Switching Relay Product Image
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    6 Zone Switching Relay SR506-4 6 Zone Switching Relay
    SKU: SR506-4
    Brand: Taco
    (123)
    $240.00 each
    174
    Mon, Nov 9
    244
    QtyArrives
    174 Mon, Nov 9
    70 Wed, Nov 11 – Thu, Nov 12
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  • 2 Zone 120V Switching Relay with DPST switching Product Image
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    2 Zone 120V Switching Relay with DPST switching RA832A1066 2 Zone 120V Switching Relay with DPST switching
    SKU: RA832A1066
    Brand: Honeywell
    (28)
    $79.68 each
    441
    Mon, Nov 9
    441
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    441 Mon, Nov 9
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  • 6 Zone Switching Relay<br>w/ Priority Product Image
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    6 Zone Switching Relay w/ Priority SR506-EXP-4 6 Zone Switching Relay w/ Priority
    SKU: SR506-EXP-4
    Brand: Taco
    (13)
    $248.00 each
    120
    Mon, Nov 9
    120
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    120 Mon, Nov 9
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  • 4 Zone Switching Relay<br>w/ Priority Product Image
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    4 Zone Switching Relay w/ Priority SR504-EXP-4 4 Zone Switching Relay w/ Priority
    SKU: SR504-EXP-4
    Brand: Taco
    (29)
    $190.00 each
    100
    Mon, Nov 9
    202
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    100 Mon, Nov 9
    102 Wed, Nov 11 – Thu, Nov 12
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  • 3 Zone Switching Relay<br>w/ Priority Product Image
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    3 Zone Switching Relay w/ Priority SR503-EXP-4 3 Zone Switching Relay w/ Priority
    SKU: SR503-EXP-4
    Brand: Taco
    (29)
    $158.00 each
    106
    Mon, Nov 9
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    106 Mon, Nov 9
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  • 1 Zone 120V Switching Relay w/ Internal Transformer, 1 SPST Product Image
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    1 Zone 120V Switching Relay w/ Internal Transformer, 1 SPST RA89A1074 1 Zone 120V Switching Relay w/ Internal Transformer, 1 SPST
    SKU: RA89A1074
    Brand: Honeywell
    (16)
    $60.99 each
    287
    Mon, Nov 9
    287
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    287 Mon, Nov 9
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  • Switching Relay w/ Internal Transformer DPST Line Voltage Relays Product Image
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    Switching Relay w/ Internal Transformer DPST Line Voltage Relays R845A1030 Switching Relay w/ Internal Transformer DPST Line Voltage Relays
    SKU: R845A1030
    Brand: Honeywell
    (9)
    $77.99 each
    107
    Mon, Nov 9
    107
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    107 Mon, Nov 9
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  • Replacement Fuse - <br>5 Amp (10 Pack) Product Image
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    Replacement Fuse - 5 Amp (10 Pack) SR5A-005RP Replacement Fuse - 5 Amp (10 Pack)
    SKU: SR5A-005RP
    Brand: Taco
    (3)
    $14.29 each
    26
    Mon, Nov 9
    92
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    26 Mon, Nov 9
    66 Wed, Nov 11 – Thu, Nov 12
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  • Replacement Fuse - <br>6 Amp (10 Pack) Product Image
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    Replacement Fuse - 6 Amp (10 Pack) SR6A-001RP Replacement Fuse - 6 Amp (10 Pack)
    SKU: SR6A-001RP
    Brand: Taco
    (5)
    $17.84 each
    67
    Mon, Nov 9
    229
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    67 Mon, Nov 9
    162 Wed, Nov 11 – Thu, Nov 12
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  • Universal Switching Relay w/ Internal Transformer Product Image
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    Universal Switching Relay w/ Internal Transformer R8845U1003 Universal Switching Relay w/ Internal Transformer
    SKU: R8845U1003
    Brand: Honeywell
    (18)
    $58.99 each
    256
    Mon, Nov 9
    256
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    256 Mon, Nov 9
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  • 2 Zone Pump Controller Switching Relay with Priority Protection Product Image
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    2 Zone Pump Controller Switching Relay with Priority Protection SP-82 2 Zone Pump Controller Switching Relay with Priority Protection
    SKU: SP-82
    Brand: Azel Technologies
    (8)
    $103.95 each
    83
    Mon, Nov 9
    83
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    83 Mon, Nov 9
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  • 6 Zone Expandable Switching Relay Product Image
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    6 Zone Expandable Switching Relay ARM6P 6 Zone Expandable Switching Relay
    SKU: ARM6P
    Brand: Argo
    (28)
    $234.99 each
    178
    Mon, Nov 9
    178
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    178 Mon, Nov 9
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  • 1 Zone Switching Relay Product Image
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    1 Zone Switching Relay AR822II 1 Zone Switching Relay
    SKU: AR822II
    Brand: Argo
    (5)
    $59.82 each
    235
    Mon, Nov 9
    235
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    235 Mon, Nov 9
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  • 4 Zone Expandable Switching Relay Product Image
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    4 Zone Expandable Switching Relay ARM4P 4 Zone Expandable Switching Relay
    SKU: ARM4P
    Brand: Argo
    (28)
    $205.99 each
    182
    Mon, Nov 9
    182
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    182 Mon, Nov 9
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  • Isolation Relay<br>(Up to 3 Zones) Product Image
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    Isolation Relay (Up to 3 Zones) IR882 Isolation Relay (Up to 3 Zones)
    SKU: IR882
    Brand: Argo
    (14)
    $69.24 each
    71
    Mon, Nov 9
    71
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    71 Mon, Nov 9
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  • 3 Zone Pump Controller Switching Relay with Priority Protection Product Image
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    3 Zone Pump Controller Switching Relay with Priority Protection SP-83 3 Zone Pump Controller Switching Relay with Priority Protection
    SKU: SP-83
    Brand: Azel Technologies
    (6)
    $125.95 each
    55
    Mon, Nov 9
    55
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    55 Mon, Nov 9
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  • 1 Zone Pump Controller Switching Relay w/ Surge & Fuse Protection (DPDT) Product Image
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    1 Zone Pump Controller Switching Relay w/ Surge & Fuse Protection (DPDT) SP-81 1 Zone Pump Controller Switching Relay w/ Surge & Fuse Protection (DPDT)
    SKU: SP-81
    Brand: Azel Technologies
    (5)
    $53.75 each
    82
    Mon, Nov 9
    82
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    82 Mon, Nov 9
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  • 24v Replacement Relay Product Image
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    24v Replacement Relay SR024-001RP 24v Replacement Relay
    SKU: SR024-001RP
    Brand: Taco
    (6)
    $24.99 each
    52
    Mon, Nov 9
    108
    QtyArrives
    52 Mon, Nov 9
    56 Wed, Nov 11 – Thu, Nov 12
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  • 3 Zone Expandable Switching Relay Product Image
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    3 Zone Expandable Switching Relay ARM3P 3 Zone Expandable Switching Relay
    SKU: ARM3P
    Brand: Argo
    (28)
    $167.99 each
    123
    Mon, Nov 9
    123
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    123 Mon, Nov 9
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  • UPZCP-1 Single Zone Pump Control  Product Image
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    UPZCP-1 Single Zone Pump Control 98996400 UPZCP-1 Single Zone Pump Control
    SKU: 98996400
    Brand: Grundfos
    (2)
    $59.99 each
    16
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    16
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FAQs, Manuals & Videos

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  • Switching relays are used to control the flow of water in a heating system by monitoring temperatures and adjusting boiler water temperature to match the demand. They are used in coordination with circulator pumps and programmable thermostats to control zoning in a hydronic heating system. This makes them ideal for indirect water heaters and priority zoning applications. They maximize efficiency and reduce fuel usage, which saves money. In addition, they provide intermediate switching of a line voltage device from a low voltage controller. Switching relays are available in one to six zone models, and if additional zones are required expandable models provide the ability to expand up to 20 zones.

    We offer a wide selection of Taco, Honeywell , Argo, and Bell & Gossett switching relays for residential and light commercial applications.

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