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Does anyone know what the hysteresis is on a Honeywell CM927

Discussion in 'Plumbing and Central Heating' started by Nerdio, 4 Jan 2010.

  1. Nerdio

    Nerdio

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    I'm looking at installing a Honeywell CM927, or maybe the wired version. I can't seem to find out what the hysteresis is on this unit. Can anyone help?
     
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  3. D_Hailsham

    D_Hailsham

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    Honeywell's spec says:

    Temperature control accuracy: ±0.5 K (nominal) @ 20°C, 50% load 3KΔ/hour.
     
  4. Agile

    Agile

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    That spec may not exactly equate to the question.

    Most modern controls allow the hysteresis to be set at +- 0.5 or +- 1.0

    For most applications its not very critical.

    Tony
     
  5. Nerdio

    Nerdio

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    Thanks
     
  6. D_Hailsham

    D_Hailsham

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    Agreed. But are we talking about hysteresis, in the true sense of the word, or just the spread between on and off.
     
  7. Agile

    Agile

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    You, I and the Nerd may all be talking about different things!

    Many of the latest stats also look at rate of temp rise and not just actual temps.

    Its a common falacy that a small differential in a stat gives better control.

    In reality there are many other factors that come into play like convection currents from heat sources, draughts etc.

    Tony
     
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