Comments on: Remote temperature sensor and e/mail notification for vacant house.

Question: Remote temperature sensor and e/mail notification for vacant house.

HuronBob — Mon, 27 Dec 2010 15:34:42 -0800

How can I monitor the air temperature at a residence I don't live at using a Mac running OS x, a usb mounted temperature sensor and a program that will e/mail me regular updates as to the room temperature?

We have a house that we purchased, but we're not ready to move into. It is somewhat vulnerable to power-outages (due to a 1.5 mile run of power wires under old growth trees from the main road to our house). The house has a hot water/radiant floor heating system, which, of course, I don't want to freeze should the power go out (I'm in Michigan).

The house has internet access, I have an iMac I can leave there (Running OS X 10.3).

I want to be able to plug a USB temperature sensor into the Mac, measure the air temp, and get an automated e/mail on a hourly basis that gives me the temp in the house.

Should the power fail the e/mails would, of course, stop, at which point I would know there was a problem. If the boiler failed independent of power, I would see the temp. readout falling in time to respond (I'm only a mile away).

I need suggestions for:

1. A USB air temp. sensor.

2. Software for the Mac that would automate the process. (this is the tough part, my googling has failed me on this)

Note: I do NOT have a land-line at the house and don't intend on getting one. And I have seen the WiFi sensors that don't require a computer, but I would like to avoid the $300 cost they bring.

By: dttocs

dttocs — Mon, 27 Dec 2010 16:01:46 -0800

The THUM is a temperature and humidity sensor which has OS-X software available. The software will send an email if the temperature falls outside specific boundaries.

I would think your larger problem is connectivity to the Internet? Or do you have cell coverage and plan to attach a Mobile Broadband modem?

I haven't tried this - you may want to check with the vendor to make sure the website information is accurate.

By: SpecialK

SpecialK — Mon, 27 Dec 2010 18:23:49 -0800

There's also a wifi-capable thermostat I saw for $75 at Home Depot the other day, so maybe that and a MiFi and you should be good to go?

By: Kiscica

Kiscica — Tue, 28 Dec 2010 07:19:43 -0800

Based on the original question, it sounds like Internet connectivity is not a problem ("[t]he house has internet access").

The first suggestion above has one major flaw: if the power has gone out, your Mac won't be on, so you won't get the email when the temperature drops out of bounds! (Presumably it will take a lot longer than any reasonable UPS would last for the temperature to drop significantly.) It's not clear from the THUM site that the included software can be configured to send regular emails - it logs to a file, though, so with minimal Unix scripting skill you should be able to set up a job to email you periodically with the last logged temperature (open up a Terminal window and type "man cron", "man crontab", "man mail", "man tail").

Of course, if the goal is simply to be informed if the power goes out, it's not even obvious that you need the temperature sensor at all! Simply set up a cron script to mail you periodically - if it stops, you know the power is out (well, that, or the internet connection, or your computer has crashed...) and you should make a visit.

By: Kiscica

Kiscica — Tue, 28 Dec 2010 07:30:42 -0800

OH. I should add the most important thing I was planning to say, which is that many (most? all? some?) modern Macs have multiple temperature sensors built in -- e.g. for controlling the fans. My Mac Pro has a bunch of them - CPU, motherboard, hard drives, ambient... yes, ambient. The ambient temperature sensor ought to give you a fairly good approximation to room temperature (perhaps off by a few degrees if the machine itself runs warm, but you can correct for that). Before we occupied our current place, I used to log in remotely to my machine and check the temperature occasionally via that sensor - never bothered with an email job, but it certainly could be done.

Google mac ambient temperature sensor, you'll probably find a bunch of programs that can read it. I used this one. It doesn't have any email capabilities, but I bet there's something out there that can do it. And even if you have to shell out for the software, at least you don't need to buy an external temperature sensor.

By: HuronBob

HuronBob — Tue, 28 Dec 2010 11:19:35 -0800

Thanks for the responses, folks, and Kiscica, for the heads up on the built in sensors... I may explore that as well....

As an FYI, I did find a suitable solution at a grand cost of $4, as follows for future reference:

1. I have an old, 1st gen flat panel iMac set up at the house with broadband access.

2. I dug up an old mini video recorder I had in the basement.

3. Purchased a $4 round thermometer at the hardware store.

I put the camera in it's base and plugged it into an outlet. Put the camera on the counter, pointed at the thermometer two feet away. Lite the thermometer with a small usb led light also plugged into the computer. Set the computer to not sleep, to reboot automatically in a power failure, and to automatically log me in and start iChat.

Found a terminal command that instructs iChat to accept any video chat request. Set up an AIM account for the house to use with iChat.

Done..

I can log into iChat at home, request a video chat with the iMac at the empty house, it accepts and I've got a picture of the thermometer. I only need to check a couple of times a day, the house is so well insulated that it will hold the heat for about 24 hours before it would become a problem.

If I attempt to connect and can't, the assumption is that the power is out and I need to do something...

Not a pretty solution, but cheap!