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Does the Laars Endurance EBP 110 circulator pump modulate its speed according to the flame output?

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Chris Alonzo
Chris Alonzo Member Posts: 45
in Gas Heating
The voltage going to my circulator keeps changing and it even goes down to 14V sometimes, causing the boiler to kettle. I was wondering if the cause is a bad boiler control or a bad PWM (modulator) board.

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  • hot_rod
    hot_rod Member Posts: 22,201
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    Read through the manual, I don’t see any mention if the pump being variable speed

    The label on the pump does it indicate VS
    IT would have 4 wires is it is a 0-10vdc controlled pump. My Lochinvar has a Grundfos VS circulator m, 4 wire.

    It could be a standard PSC circ controlled by a triac for speed control.

    If this is the model you have?

    https://www.laars.com/images/uploads/products/1117F.pdf
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Chris Alonzo
    Chris Alonzo Member Posts: 45
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    That is what I have. The circulator is a Grundfos UP15-42F. It is a 2 wire 120VAC motor. 
  • hot_rod
    hot_rod Member Posts: 22,201
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    Sounds like a standard circ, unless I’d shows MixiMiser which was a VS circulator, generally black in color with a much larger terminal box.

    If it is being controlled by a wave chopper or triac, I don’t think you can read that output with a standard voltmeter
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Chris Alonzo

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