[Hai-users] Temperature & Humidity sensor

Tue Nov 1 20:25:38 CST 2005

I doubt it, but I'll take a look. It might be awhile. If I still have it
I'll have to read it off some 20 year old 360k floppies that were written
using the old QNX2 operating system. The floppies may not be good anymore
and I'll have to dig out an old machine to see if it still boots.

If anyone has access to an ASHRAE book the enthalpy chart is in there. It's
not a simple algorithm. If you see the chart you'll know why, nothing linear
about it. However, since memory is cheap these days and with some
constraints on the input variables (limit the temperature and humidity
inputs to reasonable values) you could probably come up with a lookup table.
Would take some time but you'd only have to do it once.

By the way, how can humidity be "artificially high" :)

----- Original Message ----- 
From: "Paul | CSI" <paul2005 at cybernetics.ca>
To: "'Ken Schumm'" <kwschumm at qsolv.com>; "'HAI Users'" <hai-users at tssi.com>
Sent: Tuesday, November 01, 2005 5:23 PM
Subject: RE: [Hai-users] Temperature & Humidity sensor

> This is turning into a great thread. Given the primitive RC80 and the
> Outdoor Temp/Humidity sensor, we should be able to adapt Ken's algorithm.
> This "revolving door" takes the question back to suitable humidity
setpoints
> and accounting for rainy days where the humidity would be artificially
high.
> Perhaps Greg's idea for a rain sensor would fix that. Any chance of
digging
> up that algorithm for the thread Ken?
>
> Paul
>
> -----Original Message-----
> From: hai-users-bounces at tssi.com [mailto:hai-users-bounces at tssi.com] On
> Behalf Of Ken Schumm
> Sent: November 1, 2005 6:48 PM
> To: 'HAI Users'
> Subject: Re: [Hai-users] Temperature & Humidity sensor
>
> You want comfort? Use Enthalpy. Enthalpy measures the BTUs of heat energy
> per lb. of dry air. Moist air contains more heat energy than dry air.
> Enthalpy can be computed with humidity and dry bulb temperature inputs,
but
> you'd never be able to compute it on an Omni given the primitive
programming
> capabilities and limited access to temperature and humidity values. We
> developed an algorithm to do this about 20 years ago using a
Newton-Rhapson
> (sp?) iterative technique. The result was used to slightly increase or
> decrease temperature setpoints to save energy and increase comfort in a
> building control system. Humid summer day? Drop the setpoint a degree or
so.
> Dry summer day? Raise the setpoint. Our algorithm might be lost to the
ages
> now since that company went out of business, but it worked wonderfully.
>
> I've wondered for years why thermostat makers haven't used enthalpy for
> comfort control.
>
> ----- Original Message -----
> From: "Dan Barclay" <Dan at BarclaySoftware.com>
> To: "'Paul | CSI'" <paul2005 at cybernetics.ca>
> Cc: "'HAI Users'" <hai-users at tssi.com>
> Sent: Tuesday, November 01, 2005 2:10 PM
> Subject: RE: [Hai-users] Temperature & Humidity sensor
>
>
> > Yea.  The suggestions I made probably wouldn't help with that.  I'd
guess
> > you'd get more mileage out of accounting for direct sunlight (vs
overcast)
> > and wind speed, along with outside temp.  An indirect indication of
> > heat/cool requirements may be *attic* temperature.
> >
> > Humidity, even with infiltration, doesn't (shouldn't) change rapidly
> > indoors.  Well, I guess that depends on the definition of
> infiltration<vbg>.
> > If you get rapid humidity changes you may want to cut down on drafts to
> > reduce infiltration, and cold surfaces to reduce rapid condensation.
> >
> > It sounds like you'll get a chance to experiment with this a bit.  If
you
> > come up with something clever, let us know!
> >
> > Dan
> >
> > > -----Original Message-----
> > > From: Paul | CSI [mailto:paul2005 at cybernetics.ca]
> > > Sent: Tuesday, November 01, 2005 3:04 PM
> > > To: 'Dan Barclay'; satz at iranger.com
> > > Cc: 'HAI Users'
> > > Subject: RE: [Hai-users] Temperature & Humidity sensor
> > >
> > > What I am trying to accomplish is a more accurate way to anticipate
> > > temperature changes. The very nature of a Thermostat is to be reactive
> to
> > > ambient temperature but it doesn't take into account infiltration. In
> > > Canada
> > > we need to "bump" the thermostat a degree when it gets excessively
cold
> > > (similarly with the a/c in summer). It's common to see a 100°F
> temperature
> > > swing between Summer and Winter - and that doesn't take the humidity
> into
> > > account. I'm just looking for some ideas and what others are doing to
> make
> > > the living space both comfortable and energy efficient at the same
time
> (I
> > > know it is a contradiction).
> > >
> > > Paul
> > >
> > > -----Original Message-----
> > > From: Dan Barclay [mailto:Dan at BarclaySoftware.com]
> > > Sent: November 1, 2005 3:28 PM
> > > To: satz at iranger.com; 'Paul Whyte'
> > > Cc: 'HAI Users'
> > > Subject: RE: [Hai-users] Temperature & Humidity sensor
> > >
> > > I'm not sure exactly what you're trying to detect, but if you're
looking
> > > for
> > > an indication to use for lawn watering you should have a look at the
> > > sensors
> > > used by irrigation equipment.  The ones I've seen are simple and
> reliable,
> > > using the swelling of leather washers to trip a switch.  Most lawn
> > > irrigation companies should have them available.  The indication isn't
> > > immediate, nor does it clear immediately.  It's actually intended to
> mimic
> > > the lawn.
> > >
> > > An indication of "is it raining rat now!" would be to use a moisture
> > > sensor
> > > on a sloped surface, or perhaps level in a vessel having a slow drain
> > > (being
> > > filled from a roof valley).
> > >
> > > Of course, how you do this would depend on what you want to do with
the
> > > information.
> > >
> > > Dan
> > >
> > > > -----Original Message-----
> > > > From: hai-users-bounces at tssi.com [mailto:hai-users-bounces at tssi.com]
> > > > On Behalf Of satz at iranger.com
> > > > Sent: Tuesday, November 01, 2005 1:13 PM
> > > > To: Paul Whyte
> > > > Cc: HAI Users
> > > > Subject: Re: [Hai-users] Temperature & Humidity sensor
> > > >
> > > > You might be able to find a rain gauge that will give you a contact
> > > > closure. I don't know of any. Alternatively you would need external
> > > > access to a web site or a weather station that could provide that
> > > information.
> > > >
> > > > I am not sure why rain or snow would be an issue. You want to know
> > > > when it is higher regardless of the reason unless I am missing
> > > something.
> > > >
> > > > Thanks,
> > > > Greg
> > > >
> > > > > Here's a question for the dedicated programmers out there.
> > > > >
> > > > > I would like to incorporate some temperature code into a Pro2 that
> > > > > takes outdoor temperature and humidity into account. The problem
> > > > > with humidity is how to discern when it's raining or snowing (this
> > > > > would throw the
> > > > humidity
> > > > > values out of normal) - hence why it might be a good idea to just
> > > > > stick with temperature only. Any ideas or thoughts?
> > > >
> > > >
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> > >
> >
> >
> >
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