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Phil23
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Joined: 27/03/2016
Location: Australia
Posts: 1667

Posted: 01:10pm 09 Apr 2016

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Just not quite getting my rusty brain around temperature differential logic.
This simple code works, but doesn't allow for any differential. Like say 0.3�

If TmpCur<TmpTar Then 'Compare Current & Target temperature.
PumpStat="Running" 'Turn the Pump on.
pin(PinLed1)=1
else
PumpStat="Standby" 'Turn the Pump off.
pin(PinLed1)=0
endif

Main reason I want differential, is not for Solar control, but for when I'm using the Heat Pump. I want to reduce the amount of times it cycles on & off.

Cheers.

atmega8

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Joined: 19/11/2013
Location: Germany
Posts: 724

Posted: 02:05pm 09 Apr 2016

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.....???

HYSTERESIS ?

Phil23
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Joined: 27/03/2016
Location: Australia
Posts: 1667

Posted: 02:08pm 09 Apr 2016

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That's the term I should have used.

Ie,

When temperature gets to 34�C, stop heating, but don't start again before it falls below say 33.6�.

Guessing it will need some sort of cycle flag.

Cheers

atmega8

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Joined: 19/11/2013
Location: Germany
Posts: 724

Posted: 02:38pm 09 Apr 2016

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This Is very simple.
HYSTERESIS is done by a Schmitt-Trigger.
You need a software Schmitt-Trigger like this:

if( Input > top)
LED = 1

else if( Input < min)
LED = 0Edited by atmega8 2016-04-11

robert.rozee
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Joined: 31/12/2012
Location: New Zealand
Posts: 2428

Posted: 05:22pm 09 Apr 2016

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try the following:

hyst = 1

If TmpCur<(TmpTar-hyst) Then 'Compare Current & Target temperature.
PumpStat="Running" 'Turn the Pump on.
pin(PinLed1)=1
endif

If TmpCur>(TmpTar+hyst) Then 'Compare Current & Target temperature.
PumpStat="Standby" 'Turn the Pump off.
pin(PinLed1)=0
endif

when the current temperature falls 1 degree below the target temperature, the pump is turned on.

when the current temperature rises 1 degree above the target temperature, the pump turns off.

cheers,
rob :-)

Phil23
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Joined: 27/03/2016
Location: Australia
Posts: 1667

Posted: 08:39pm 09 Apr 2016

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robert.rozee said try the following:

Thanks Rob,

That's basically what I came up with once I rested my brain & could thing logically again.

If TmpCur<(TmpTar - TmpDif) Then
PumpStat="Running" 'Turn the Pump on.
pin(PinLed1)=1
else if TmpCur>(TmpTar) then
PumpStat="Standby" 'Turn the Pump off.
pin(PinLed1)=0
endif

Just not swinging on the high side of the set temp.

Will just have to add a minimum wait timer on it for when it's in heat pump mode now so the compressor unit can depressurise.

Have found a good example some else has done of Ardurino over here.
Phil.

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