Tomasz Korwel
programmer, administrator, engineer – my everyday fights with reality

If you want to use SUN’s java version with rxtx on any debian derivative system you’d be surprised to discover that jre can’t find rxtx libraries if you installed them using librxtx-java package. It’s because SUN does not adhere to debian naming and placing policies and looks for libraries in wrong place. Quick fix:

cd /usr/lib/jvm/java-6-sun/jre/lib/
cp /usr/share/java/RXTXcomm.jar ./
cd i386
cp /usr/lib/jni/lib* ./

That will make those libs available to SUN’s java and everything should work from now on.

1. Download and unzip api:

wget http://xbee-api.googlecode.com/files/xbee-api-0.5.5.zip
unzip xbee-api-0.5.5.zip

2. Install

mvn install:install-file \
-DgroupId=com.rapplogic \
-DartifactId=xbee-api \
-Dversion=0.5.5 \
-Dfile=xbee-api-0.5.5.jar \
-Dpackaging=jar \
-DgeneratePom=true

One of the nicest features of our new HVAC zone system is module called balanced controller. Basically it’s an algorithm calculating heat demand in every zone and opening and closing registers accordingly.

Here you can see that one of the zones (middle one) was fully open while remaining two were just barely moved, Then when this zone was satisfied in it’s heat demand it was closed and the first one was fully open to direct all hot heat into this zone to shorten furnace running time to the minimum.

I don’t have any statistic data to prove my theory yet but it seems to me that such behavior shortens greatly overall running time and simply saves us money.

Looking at the graph (and trying to keep my fingers from freezing):

I noticed interesting thing – the temperatures in my office tend to go down a bit every day (look at those last four green peaks). Keep in mind that my thermostat is set to the same temperature as it was before, yet those temps really go down. Looking for explanation I tried to remember what changes in weather did we observed during those last 4 days. Did it become colder outside? Not really. Maybe hotter? Naa… Rained? Snowed? Was it windy? And then it strike me – we got more and more sun each day. So apparently upper level of our house acts as greenhouse absorbing energy from sun. And because the thermostat is in fact mounted there, lover level rooms, not exposed to radiation heat became colder and colder.

One additional reason why giving those rooms more decision power as when to turn the furnace on is not that bad idea.

I installed 2 motorized registers and set the system to run in passive mode.

Here you can see:

how it nicely flattened the temp curve by closing the registers when temperature reached setpoint.

Time to finish the rest of the house.