I use two basic programs in my ISY994. The first is a cycler that runs off my HVAC clock, basically a 40 minute cycler, overriding a self loop of 1 hour, in case the HVAC cycler ever stalls.
CCell.dewPoint Control - [ID 00F7][Parent 00BD]
If
$sHVAC.sync.clock is $cTRUE
Then
Wait 1 second
Repeat Every 1 hour
Run Program 'CCell.dewPoint Control.2' (If)
Repeat 1 times
Else
- No Actions - (To add one, press 'Action')
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The second program decides whether the ventilation will be beneficial lowering the dewpoint but I need some ventilation regardless as I have bank of lead-acid batteries in the wine cellar also.
CCell.dewPoint Control.2 - [ID 0127][Parent 00BD][Not Enabled]
If
$sHouse.dewPoint.Ccel > $sHouse.dewPoint.out
And $sHouse.dewPoint.Ccel > 3
Then
Set 'Cold Cellar / Ccel Ventilation Fan' On
Wait 50 minutes
Set 'Cold Cellar / Ccel Ventilation Fan' Off
Else
Set 'Cold Cellar / Ccel Ventilation Fan' On
Wait 1 minute
Set 'Cold Cellar / Ccel Ventilation Fan' Off
Higher dewpoint means air contains more moisture.
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My dewpoint program is a twisted fudge calculation to approximate the temp/Rh into dewpoint chart curves. Since inception of my programmes, the CAO Tag Kumoapps scripting now offer a dewpoint field option that can be directly transmitted into my ISY994 variables instead, but I haven't updated that yet.
Sync.DewPoint.ccel.Tag2 - [ID 0048][Parent 0101]
If
$sTag2.humidity >= 0
And $sTag2.temp <= 40
And $sTag2.outOfRange is $cFALSE
Then
$House.dewPoint.scratch2 = 100
$House.dewPoint.scratch2 -= $sTag2.humidity
$House.dewPoint.scratch1 = $House.dewPoint.scratch2
Repeat While $House.dewPoint.scratch1 > 45
$House.dewPoint.scratch1 -= 45
$House.dewPoint.scratch1 *= 0.7
$House.dewPoint.scratch2 += $House.dewPoint.scratch1
$House.dewPoint.scratch1 = 0
Repeat 1 times
$House.dewPoint.scratch2 /= 5
$House.dewPoint.scratch2 -= $sTag2.temp
$House.dewPoint.scratch2 *= -1
$sHouse.dewPoint.Ccel = $House.dewPoint.scratch2
Else
- No Actions - (To add one, press 'Action')