Tuesday, October 8, 2013

XTension saves my crawlspace

What is home automation good for other than remote control of your lights is an oft asked question. I collect a lot of data about things, especially things I can't see easily without it and good information is hidden in there.

I have a very fancy and expensive encapsulated crawlspace under this house. It's one of my favorite things. No longer is it moist, and moldy and wet and full of bugs under there. It's sealed up and dehumidified and it's so clean we could have tea under there when you come to visit.

One of the things I monitor is the duty cycle of the dehumidifier. That device has a dedicated circuit that runs under the house to power it so just outside the electric box I added some monitoring equipment. Since the dehumidifier has a passive humidistat it's almost totally off when it's off so that makes it easy to tell if it's on or not. I used a 120v HVAC sensor. They are for turning on a booster fan when the main blower turns on. You just pass one wire of the feed to the main blower through it's sensor loop and it will switch on it's load when that load reaches a certain point. You can't really adjust them so they aren't useful for things with a more complicated power usage structure (like the sump pump down there which I also tried to do this with but which never worked because the charger circuit on the battery backup pump kept it on all the time) So I used that HVAC switch to control a 120v relay which provides a dry contact which you can read into XTension in many ways. Mine is connected to a weeder digital card.

The duty cycle of that has been around 4% since a few weeks after it had been installed and dried out the space under there. I still display it on my Web Remote because that number going up could mean equipment problems or some other issue under there.

Yesterday I noticed that the duty cycle was at 15% and knew there was a problem. Sure enough the little hooks that held the access panel in place from the outside had finished rusting through and the door had fallen open. It had probably been open only a few hours before I noticed it and was able to fix it keeping me from having bugs and skunks and god knows what move in under the house.

I think I'll place a door sensor on the access panel now too.  You can't get from there into the house without a sawzall but still it would be good to know if the door comes open.

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