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Electric Boiler and short cycling

Hilly
Hilly Member Posts: 428
in THE MAIN WALL
Is Short Cycling a big issue with an electric considering it is nearly 100% efficient? I know components will suffer shorter life expectancies but is that the only concern? Am I wrong that short cycling concerns are mainly an efficiency concern?

Comments

  • SWEI
    SWEI Member Posts: 7,356
    edited August 2014
    Efficiency and comfort

    What kind of controls are on the system?  If it's a bang/bang thermostat, you will get greater temperature swings than you would with PWM -- even for a single element.  How big is the boiler?  For smaller sizes, you can use a line voltage thermostat directly, but adding a contactor for larger elements (up to a point) is not very expensive.
  • Zman
    Zman Member Posts: 7,609
    Demand Meter

    In addition to SWEI's response,

    On premises that are "Demand Metered", is is a good idea to have multiple elements and stage them. Bang Bang thermostats with leave you with very high demand spikes which will raise your rates.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • hot_rod
    hot_rod Member Posts: 22,791
    older style

    electric boilers had magnetic contactors, frequent, short cycling wasn't kind to those contactors. Plus the noise and lights dimming :)



    Most of the current electric boilers have triacs controlling them, for variable outputs and soft starts. Triacs, electronic relays, are very rugged devices.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • SWEI
    SWEI Member Posts: 7,356
    Right, and for older units

    you can use a line voltage PWM stat (which has its ownTRIAC) to trigger a zero-crossing solid state relay for larger loads.  You can also phase chop (dim) them with 0-10V control signals for full modulation (at the cost of some increase in line noise.)  Works well with ODR controls.

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