Whole-House Sensors...

[AC_Hacker]

I've been wanting to install 1-wire sensors in every room of my house in order to study how heat affects my house and how it moves through the house in the winter.

I finally got it working.

!-wire sensors are very accurate and if you get them direct from China, they're real cheap ($1/ea). They are meant to be wired in as parallel sensors, and a micro=controller can query them, and since they each have a unique number, the micro-controller can keep it straight, which data is arriving from each sensor... pretty cool.

I installed a sensor in each room of my house (7 rooms, including basement) at about the same height (4').

I won't elaborate on the work of installing the string except to say that they are designed to be in a serial topography. I decided to try some branching, to see how it worked (saved a lot of wire), and I didn't run into problems, probably because my house is so small.

But the last sensor is of interest because it is mounted outside in the weather, and the sensor needed to be protected from wet and also from bugs.

Below is the pile of parts, all standard plumbing, 1/2" CPVC

Above is the 1-wire sensor mounted to a tiny board to make assembly easy


Below is the floor flange and the pipe-thread to CPVC adapter

Above, I am making sure the flange will fit flat to the house.


Below is the flange securely screwed (coated screws) to the house.

Above is the cable threaded through the "T" connector.


Below, the "T" connector is correctly positioned and screwed to the house

Above, I am drilling a weep hole that will let water pass through but not bugs


Below, the end cap is glued into place

Above, I am drilling small holes in the pipe for the 1-wire sensor


Below, I am checking the pin-out of the 1-wire against my notes

Above I have soldered the 1-wire to the cable


Below, I am verifying that the new sensor is working

Above, now that I know it works, I glue the top into place


Below is the first test of the sensors fifteen minutes, fifteen readings.

I suspect that he large excursion is because of handling (prior to final assembly).

Working OK!

Best,

-AC

[michael]

Have you any further data? Will you post the source of the one wire sensors? What sort of microcontroller are you using? Did you construct the data collecting set up from parts, and if so will you show photos of it? Did you write the code the microcontroller uses, and if so will you share that code? Is the microcontroller performing any task other than logging the temperatures?

Michael Moreland
Mendocino, CA

[AC_Hacker]

Originally Posted by michael

Have you any further data?

I'll post recent data later today.

Originally Posted by michael

Will you post the source of the one wire sensors?

Yes, I got them from China via ebay. The part number is DS18B20. If you specify your search for 'buy it now' and also 'price + shipping: lowest first', you will very quickly zero in on your best pick. I got 20, so I'd have more for future projects.

Originally Posted by michael

What sort of microcontroller are you using?

There is a local guy (Travis) who designed a simple, open-source Arduino logger board for his own use... he also sells them. It works right out of the box, but it can be modified and expanded if you are technically inclined. Available HERE.

Originally Posted by michael

Did you construct the data collecting set up from parts, and if so will you show photos of it? Did you write the code the microcontroller uses, and if so will you share that code?

The logger is open source, the schematic is on-line, as is the source code. But, for $45, trying to DIY just might be a 'fool's errand'.

Originally Posted by michael

Is the microcontroller performing any task other than logging the temperatures?

The hardware and software are designed with the possibility of adding additional capability. So far, I have not taken advantage of this flexibility.

As it comes out of the box, it writes all data to a SD card. There are also serial pins available. So far, I just let it run, then stop it, and remove the card and dump the data into my PC, where I import it into a spreadsheet program (Gnumeric). I want to add a serial link so that I don't interrupt logging.

The logger records a sample every minute, which is more frequent than I need. I think that a sample every 5 or ten minutes would be sufficient. I am also looking into a 'data smoothing' routine, that would add the results of a number of readings (X) and then divide the summed numbers by X, and write that average to the SD card.

But even without those modifications, it is very useful.

Best,

-AC

[AC_Hacker]

Here's a graph of a seven day 'warm spell' that passed our way.

...about half way through the 4th day, I started using the 1st floor front room air conditioner. The discontinuity is clear to see.

There's a lot to learn from this graph.

Best,

-AC

[michael]

Thanks, AC, for the information you provided. I have quite a number of those same sensors purchased, perhaps, from the same source. I will look into Travis’ logger board. It’s somewhat less expensive than the one I’ve been wanting made by EME Systems in Berkeley, CA. That one is called the OWL2pe data logger and can be seen at New elfOWL data logger, OEM BASIC Stamp pe. The OWL is considerably more expensive, but it appears that it comes with a serial port or at least the capability. I think you can use your spreadsheet application to do the data smoothing automatically, if you want. I’m very impressed with what you’re doing, and a bit envious. I hope you’ll keep posting data as you log it. mm

[AC_Hacker]

Originally Posted by michael

...The OWL is considerably more expensive, but it appears that it comes with a serial port or at least the capability...

The Owl looks pretty good.

The Multilogger also has serial pins on board, and has the serial communication routine built in. I'm not entirely sure if it will simultaneously log to SD card and also to serial port.

They both look pretty similar to me. The thing is to get one and get it up & running.

Kind of a 'just do it' moment.

Best,

-AC