DIY Zoning

Competition: Nest: Let Me Try To Help

2012-01-27T11:22:00.000-07:00

Like I was saying earlier, Nine out of ten people trying to change the temperature on the webapp and mobile app after being exposed to the actual hardware are observed making circular motions with their index finger and having a puzzled face. It was more difficult on the webapp than it was on the mobile app, because the latter has visible arrows (which some people managed to miss) whereas the former doesn't.

So I wonder, why didn't Nest designers implement this feature and where their usability expert was looking? I'd call this a major goof for a company that paid so much attention to slick hardware design. Or maybe they just underestimate the number of users (of which just Android user base, according to Nest page at Android Market, is between 1000 and 5000 - and I bet that this is a small fraction of users for it looks like the device is targeted at iOS user base)? Or they just don't care?

Well, let me try to help.

You'd think that tracking a circular gesture on a square screen would be difficult? Not at all.

Take the touch coordinate. Convert it to polar coordinate system against the center of your thermostat image and work in it thereafter.
Take the drag coordinate. Keep the thermostat pointer directed at the drag point - it is easy because after polar conversion you have the angle, hence, the setpoint. You don't care much about the radius.
Take the release coordinate. Send it back to hardware.

Voila.

Now, I wonder, how much time it'll take them to implement it? Or they declare the clickety-click the new standard for UI usability?

Competition: Nest: Three Weeks Later

2012-01-27T10:50:00.000-07:00

Disclaimer

Of course I'm fiercely biased, this is competition. However, observations below are based on objective and reproducible measurements. And you've been warned.
Some observations here will duplicate those listed in Black Box Analysis, however, those were initial impressions and these are long term annoyances.
"Apple hater" comments will be marked as spam.

The Good

Yes, it looks good on the wall.
Yes, the ring feels good.
Yes, it does recognize when you come close and turn on.
Yes, you can control the thermostat via webapp and iOS application.
There seems to be no problems with WiFi connectivity (Update 01/29: I jinxed it. It lost the connectivity earlier today and stayed offline for over three hours. Had to manually reconnect, don't know if it would do it automatically).
It works.

The Bad

[dup] Temperature displayed is the setpoint temperature, not the actual temperature. You can have a vague idea about what the actual temperature is by looking at it, but there's no indication when it will call for heat or cool - which causes people to jerk it unnecessarily - and the end up overcompensating most of the time (yes, even 0.5°C too hot is too hot).
[dup] Both setpoint and actual temperature display resolution is 1°F and 0.5°C, this is not sufficient for some conditions.
[dup] There doesn't seem to be a way to change the hysteresis from the default. This will cause short cycling for smaller rooms, and stale air for bigger.
[dup] Neither web app nor mobile app honor the °C measurement unit for ambient temperature - three weeks later and counting.
It is not possible to see whether the thermostat is in heating or cooling mode - there are several months of up to 20°C (40°F) daily temperature swings, it would be useful to learn how to tune the thermostat to minimize energy use.
Nine out of ten people trying to change the temperature on the webapp and mobile app after being exposed to the actual hardware are observed making circular motions with their index finger and having a puzzled face. More about that later.

The Ugly

Schedule is not practical to edit on the thermostat itself, if I were them, I'd just skip it on the device altogether - but that would be losing a bragging point, so they had to do it.
Schedule is painful to edit even on the webapp and iOS app - of course it is, if all you have is one button. Clickety-click. No gesture support. Just for fun, calculate the number of clicks it'll take to change 7 schedule points two degrees up, half degree at a time (no, I'm not doing it for you).
You can't specify "away" as a schedule item. You'll have to manually specify a low or high temperature, but then if you have to change the away temperature for some reason, you'll have to comb through all the schedule again. One click at a time.
There is no "hold" functionality. You are at the mercy of the schedule. Yes, you can specify a set "away" temperature and set it to "away" state, but that's an ugly hack.
And this hack won't work on an Android webapp.
Speaking of which, its functionality is severely limited compared to webapp an iOS app. The only thing you can do is to bring the thermostat out of "away" mode (but not put it back) and change the setpoint (see update at the bottom).

It Is Not That Learning

The main selling point of the thermostat (so important, it is the part of the name) is grossly overstated.

The schedule it learned has little to do with what is actually happening.
The "auto-away" feature takes anywhere FROM FOUR TO SEVEN HOURS to activate. Given the fact that I'm spending on average 10-12 hours and away for the rest, that is 30-70% waste as opposed to 4-5% waste in case when auto-away was kicking in after 30 minutes.

Verdict

It's just a fancy thermostat.

Is it worth $250 plus shipping? Not to me. However, if following conditions were met, it would make think again:

Setpoint and temperature display resolution at 0.1°C/°F. Or, at least, configurable resolution.
Indication of how soon the thermostat will call.
Indication of whether it is heating or cooling.
Configurable auto-away timeout.
"Away" option in the schedule.
"Hold" feature.
~~Working Android application~~ (see update at the bottom).
Same circular gesture changing the setpoint on the webapp and mobile app, instead of clickety-click.
Gesture support in schedule editing.
Added bonus, open APIs that will allow Nest interoperability with other systems

Afterword

All the features I want can be implemented either in firmware or software. Whereas I'm not holding my breath for it, this article will be updated if/when these features arrive.

UPDATE: +sid informed me that it is not that Android application is inferior to iOS, it's that both of them (when running on the phone) are inferior to their tablet counterparts (can't say anything about Android tablet, however, haven't seen it), but, in portrait orientation. To get to full functionality, you need to switch the phone orientation to landscape - then all the functionality becomes available. My apologies to Nest folks, I simply never turn my phone sideways unless I have to type. And there's no indication whatsoever that anything beyond what is visible on the screen is available.

This, however, highlights the fact that mobile applications didn't get the attention they deserved. And the webapp still doesn't look right on small screens.

More comments from +sid (verbatim) with my smart aleck comments in italic:

Nest pretends to follow Apple in packaging, but they lack attention to details - uneven space between the box and box cover, color paper over the box does not cover the box from edge to edge. You will see that Nest is far from Apple in packaging if you unpacked products from both companies.
Learning finished within two days (on weekend) and the only thing I got in schedule - 68 °F on Friday night - so much for learning
It is not obvious that if you want to have more settings on iPhone then you need to turn your phone into landscape
I have no idea how long it takes to get into "Auto-Away" mode, but three-four hours after I left home I see Nest with Auto-Away
Regular Away mode does not get terminated when I walk back home - I have to manually turn Away off
I am not 100% certain but I get a feeling it learns and estimates how long it will take to heat the house to set temperature
I am really enjoying accessing my thermostat on the go :) - that's because you aren't using the DZ app :)
°F/°C is not consistent - when you switch to °C some other stuff still shown in °F (like outside temp in iOS app)
I had no issues with getting visual indications on Nest calling for heat (it turns orange) - I didn't say I didn't see when Nest was calling, I said that it doesn't show any indication of how soon it will. Subtle difference.
You need to get used to their way to show current and set temp

DZ 3.6.5 Release Is Out

2012-01-27T00:58:00.000-07:00

Download from SourceForge
Download from Google Code
Download from Ohloh
Get source code from Subversion
Get the hardware and start enjoying your home
Tell us what else we missed

Changes since 3.6.4

The most visible change is the Swing console color scheme change from Swing (light) to Android (dark). Also, after a long wait the space "intentionally left blank" has shrunk, and the console now displays the temperature trail for the last several hours. Not only that, the chart line color varies depending on system state, and it is now trivial to visually identify trouble spots. More about that later.

The most important change, however, is the HTTP connector v.2 which allows a DZ installation to be controlled from anywhere in the world via webapp and Android application.

Competition: Nest Learning Thermostat: Black Box Analysis

2012-01-05T00:43:00.001-07:00

Since Nest is the only competing product you don't have to take a loan in the bank to own (well, maybe just a small loan), it was interesting to get a first hand experience with it. So, I bought it and installed next to one of DZ sensors.

I am reluctant to talk to my competition because the amount of information they can extract out of my questions significantly exceeds the amount of information they can extract of my most honest answers to their most detailed questions. --GT

Well, the experience was definitely interesting.

The Excellent

The most impressive (from usability standpoint) thing about the installation process is how they implemented pairing the device with the online account. I created the account (took a split second) and several seconds later, when I turned to face the thermostat (less than a meter away), it was already displaying the message asking whether I want to associate it with the account I just created. Under the wraps, it is pretty simple to someone in the trade (they probably matched the WAN IP to serial number and account name to the IP it was created from), but nevertheless very impressive. Definitely karma bonus for creativity.

The Good

No-brainer installation for someone with hands growing out of shoulders.
It was impressive that it correctly determined wiring.
It was really simple to configure it to work with the existing system (those who know how many variations of thermostat wiring and systems are out there will be definitely impressed by this).
Upon connecting to WiFi, the device immediately downloaded the update.
There's just a few seconds latency between the device and the web app.
Control algorithm seems to be smarter than just a simple hysteresis loop, will see how smart later.

The Neutral

Temperature displayed is the setpoint temperature, not the actual temperature.
Both setpoint and actual temperature display resolution is 1°F and 0.5°C, this is not sufficient for some conditions (good example: the room with little air getting to it, while the other room next to the HVAC unit gets more than it bargained for). Making this happen, though, will destroy the "Apple" aesthetics.
Not sure how successful will be WiFi connection when a DHCP server is not present. Too lazy to try, hope they did something smart.
Initially, I thought that the device was blind as a bat and doesn't sense presence right, but then realized that it's just doing it in its own way.

The Bad

It was quite painful to enter a 21 character passphrase for the wireless network.
It took two reboots and about 10 minutes to download and install the update.
There is no indication of how close the thermostat is to calling - itchy fingers *will* try to bump the thermostat if they feel too hot or too cold.
Settings change sensitivity is, unexpectedly, extremely high compared to setpoint change sensitivity - the latter is less than 1:1, and the former is almost trigger fast. Uncomfortable, and is a violation of the principle of least astonishment.
There doesn't seem to be a way to change the hysteresis from the default. This will cause short cycling for smaller rooms, and stale air for bigger.
The maximum "away" temperature setting for cooling mode is just 90°F. Folks, this is not enough for hot climates - I *work* comfortably at 90°F, and won't be afraid to set the away temperature to 100°F on the second floor.
Actual temperature is not easily visible over the "grill" (and for °C, good luck trying to distinguish "22.⁵" and "22°").
Web app and mobile app don't honor the °C measurement unit for ambient temperature. ~~While we're at that, why don't they display other data available from Weather Underground (which is their data source)?~~ (The weather is displayed as a background picture)
Standard 18 AWG thermostat wire doesn't fit into the base, had to use thinner wire. I had a patch panel for wiring so it wasn't a problem, but good luck doing this if all you have is the cable sticking out of the wall.

The Ugly

Fingerprints all over the glass.
Guess what two users tried to do (independently from each other) when asked to change the setpoint on iPad app. Correct, they tried to replicate the circular movement that it takes to change the temperature on the actual device. Instead, they were presented with ancient up and down arrows. Come on, folks, *I* did better than that, gesture detection is not that complicated.
Entering several spaces in the passphrase was most excruciating. Hint to Nest developers: it is possible to use all that nice space between the alphabet and done/cancel/backspace symbols that you already have, and plant some spacebars right there. Yes, in every shift mode. Won't hurt. Took quite a while to figure out that those spaces are currently just for decoration and aren't functional.
And it was completely infuriating when after spending about two minutes of entering the passphrase the thermostat happily reported "failed to connect" (it was a transient failure) and... displayed the EMPTY prompt again.
Let me just say this... Don't even try to use their webapp on a mobile phone. Their "beta" is not Google's "beta". More like "alpha". At $250 plus shipping a pop.
~~Where is my Android app?~~ Right here: Nest Mobile. Pretty basic, though, nothing to write home about.

The Verdict

Short version: Meh.

Long version:

Hardware looks to be decent (though, just like I suspected, there's not much stainless steel, it's mostly plastic).
Embedded software (on the thermostat itself) is perfect as far as usability is concerned, but passable as far as climate control is concerned (no comments about learning ability, that'll be covered later).
Web front end is definitely in alpha stage. Let's hope that they are planning to advance it, or at least make it work right on a wider variety of devices.

Applicability

All the information above is pertinent to model Diamond-1.10, display software ver. 1.0.4, base ver. 3.5.2/1.1, as of January 5 2012.

Competition: Nest Learning Thermostat: Teardown

2011-12-29T15:10:00.000-07:00

Sparkfun published a nice article about Nest teardown.

I wonder if the battery is replaceable other than by "contacting technical support" (update: from the link below - no, it is not replaceable).

As usual, comments are as useful as the article if not more.

C Wire-less Setup

In particular, here's a link to an article describing a subtle problem: Undocumented Nest incompatibility with single-stage wiring. Incidentally, all three of three HVAC units I have do *not* have the C wire. Here's what Nest has to say:

When Nest needs a common "C" wire
Should my B wire go in Nest’s O/B connector or in the common (C) connector? (this one is actually very important because it is a thinly veiled liability disclaimer ("If a common wire is inserted into any connector other than C, it may blow a fuse in the HVAC system and damage Nest"). Be sure that your B wire is not actually a C wire. It would be nice if they provided a way to determine this for sure using something as simple as a multimeter, more on this later.
Power Specifications for the Nest Learning Thermostat
Does Nest need a common wire?
What do Nest's wiring errors mean?

Would it be a regular dumb thermostat with nothing but dry contacts, I'd fiddle with wires. With this device, I guess I'd go for their installation service if there is anything out of ordinary. Or spend more time digging the actual wire layout. By the way, DIY installation video doesn't even hint at this problem, which makes me think there'll be lots of pissed off overconfident DIY dudes with attitude killing their Nest and blaming the manufacturer for that. Their Returns & Cancellations page is mum about what is gonna happen if the thermostat comes back dead because of customer's fault, it'll be interesting to see how this gets handled.

Afterthought: Multi-zone Setup

I missed the How does Nest work if I have multiple Nest Learning Thermostats in the same home? article when I was writing the original review. Stark contrast with DZ approach: one relatively expensive control panel per user (optional) and lots of dirt cheap sensors vs. many expensive control panels. The other side of the equation, though, is Apple aesthetics, learning capability and ability for everyone to control the temperature vs. powerful, though not quite below-average-IQ-friendly scheduler and unlimited tinkerability (at high price of your involvement, of course). These products are for totally different markets, that's for sure.

Early Access: DZ on Android

2011-12-15T18:05:00.000-07:00

Effective immediately, Android remote control application is available.

Visit the forum to find out more.

Competition: Nest Learning Thermostat

2011-10-31T00:27:00.000-07:00

Brent brought the news about Nest Learning Thermostat. Mandatory review follows.

THE GOOD

Supposedly good design and excellent workmanship.
Equipment check that is eventually done right. I wonder why nobody thought of that before, usually this information is buried deeply inside technical manuals (and good luck if you lose one).
Subtle interface cues to what is going on (I did this first almost two years ago, though).
Remote control. Guess this is the new fad.
Outside weather awareness.
Supposedly helps you saving energy. Gives you energy usage statistics.
Multiple thermostats working together.
Massive amount of documentation (go to support site and click on the arrow next to the "search" box without entering any search terms).

And to finish the panegyrics, here is a welcome thought:

I wonder if the largest effect might be getting people to voluntarily interact with the thermostat at all, thereby thinking about their HVAC more. The fact is that most of us only think about our heating and cooling systems when they’re not working. If we start thinking about them when they are, we could save more energy. The nest is so appealing to interact with that it might shade that in the energy-saving direction.

If for nothing else, creators of Nest deserve high praise for this effect alone.

THE BAD

First and foremost, this is just a banal thermostat. With it, you inherit all problems inherent to banal thermostats (a comprehensive explanation is at our FAQ). The main issue, again, is:

Thermostat makes itself happy. It doesn't care about you. It is not where you are.

In other words, it didn't cross the fundamental border between where the sensor is and where the control unit is.

Other than that...

Apple lovers will be, no doubt, excited by this device and the promise of "Apple quality". Everyone else might have a doubt (for example, when they say "stainless steel", I ask "how thick?". Need to touch it to actually confirm this statement).
Needs to be installed where it has a constant (or at least frequent) view of you. And where are thermostats normally located? Correct, in the corridor, next to the air return. Good luck making the thermostat aware of you in a big house, or if it is located in a place you normally don't walk through often.
Remote control with no fuss means external server the thermostat is talking to. Keeping it secure requires you having the account at it, and sending *your* data to it. Oh, by the way, prepare to deal with it. This is the only way one can do it without the fuss. We're doing the same. So will everyone else.
Outside weather awareness means external sensor. Or always-on internet access and temperature resolution down to city or so. Which is pretty much useless to you.
Speaking of which, support site search... Let's just say it could be better.
Even though zoning support is advertised, it will be limited for one simple reason: zoning systems need much more granular signal than just on/off.
iPhone and iPad only? Again? Where's my Android app?

THE UGLY

I want to buy this product on Newegg or Amazon. I don't want to engage in a process as complex as house refinancing, and be subjected to individual pricing based on how much I am apparently willing to cash out.
Did I forget to mention? I want to know the price up front.
A blog without an RSS or Atom feed? Is a clog.
Customer reviews for a product that is not being publicly sold? That's not a good smell in my book.
"Invitation only" procurement model suggests that not everything is as shiny as the outside ring of Nest thermostat, and it may not be as production ready as they want us to believe.
The knee-jerk reaction of my son to seeing the demo was: "One button? Again? I'm sick of one button!". Couldn't agree more. Two quotations come to mind immediately:
- If you create a system that any idiot can use, then only idiots will find it useful.
- Make things as simple as possible, but not simpler.

THE UNKNOWN

Their documentation is very good, and lots of unknowns have already been resolved. However, there are fundamental questions that are left unanswered:

~~The price for the device~~ $249 plus shipping;
The price for Nest account;
What they do with your data;
Do they allow you to take it away (like others do);
Does the device and infrastructure support open protocols, or it is as closed as everything Apple ever did?

And if the account turns out to be free, but you can't take your data out? Then you are the product being sold.

UPDATE (2011/11/02): Price was published.
UPDATE (2011/12/06): BGR published a short review. Comments deliver.

Early Access: SwitchDamper

2011-09-13T23:09:00.004-07:00

For years, DZ was able to control modulating dampers.

It seems, however, that bang-bang dampers still have their place, hence, SwitchDamper was added to Subversion and will become a part of the next release.

Now you can use DZ to control any HVAC actuator that is controlled by a switch. This includes, in particular, but not limited to:

existing open/close dampers normally controlled by 24VAC;
electric heaters that are configured as auxiliary heaters in a complex zoned system;
hydronic, geothermal and steam system valves.

DZ 3.6.4 Release Is Out

2011-03-11T21:55:00.002-07:00

Download from SourceForge
Download from Google Code
Get source code from Subversion
Get the hardware and start enjoying your home
Tell us what else we missed

Changes since 3.6.3

Fixed the Yesterday bug;
Significantly improved JMX instrumentation and system configurability without restarts.

Open Letter to SeedStudio

2011-01-07T12:43:00.003-07:00

A while ago I purhcased a couple of relay shields from your site and was recommending them to my project's users . Unfortunately, you discontinued the original product and no documentation, nor any forwarding or upgrade information, is available.

Even though a new version of the product now exists, it is not immediately obvious to my users whether the new product is compatible with the old, and whether it can be used as a drop-in replacement.

Other open hardware manufacturers retain documentation for even discontinued products available indefinitely (example here), because even though the product is discontinued, there are many instances of it in possession, and sometimes open source project maintainers need to support products that they don't have in their hands (such is my case).

It would be much appreciated if you could consider making the documentation for the old version available, and providing version compatibility notes on both old and new devices so people without deep technical knowledge could be sure that the new version of the product can be used instead of old. Including a link to a new device on old device's page won't hurt either.

Thank you for consideration,

--vt

PS: The text above was sent to you a few months ago, but there was no response. Since then, it came to my attention that not only relay shield was upgraded, but also the UartSB V2.2, and possibly others. The pattern is obvious - you're upgrading devices as soon as you run out of stock of components you could get for the cheapest price. That's OK, everyone has to make a living. However, if you respect people that make your bread and butter just a tiny little bit more, you might get more respect, which will definitely make your sales better. On the other hand, if you are an uncertainty, you are a risk. If you are a risk, you are a threat. Threating your customers is a bad business strategy.

For now, I will only recommend your products only if there is no other alternative, and a clear link to this post will be included next to recommendation. Your competitors' products will be recommended instead, even if the price is higher. Good luck.

Emme: The Vaporware of 2010? [Update: Yes]

2010-09-15T00:55:00.006-07:00

Emme was discovered in December 2009, slated for release in April 2010, then delayed until July, then until August.

It's now the middle of September, but the registration page still lists August as the availability target.

Tsk-tsk-tsk...

Maybe all it is is a market research tool? Too many things seem to be stuffed into one body, thus violating "do one thing, do it well" principle.

Especially interesting is the claim about, quote,

patented algorithms to identify most individual appliances and electrical devices, giving you insight into your energy use that to this point was unavailable.

Show me the money, or I call it snake oil.

And I still can't find my hat after it's been blown away by a promise of supporting whole three wireless sensors.

UPDATE (January 1 2011): registration page still lists August 2010 as availability date. I guess they gave up.

UPDATE (January 21 2011): the date on the registration page is gone, and it claims now that "Emme products are available nationwide through our extensive dealer network". Oh well. Let's see now how long will it take them to materialize. With three wireless sensors.

DZ 3.6.3 Release Is Out

2010-08-24T23:59:00.004-07:00

Download from SourceForge
Download from Google Code
Download from Ohloh
Get source code from Subversion
Get the hardware and start enjoying your home
Tell us what else we missed

Changes since 3.6.2

Fixed the Cold Start bug;
Improved XBee device handling upon late arrivals.

Dilbert Creator Weighs In

2010-08-24T07:14:00.004-07:00

Scott Adams wrote an article called How I (Almost) Saved the Earth.

If you care to read and see through the usual Dilbert language, there are quite a few good advices on what and how to do (and not to do).

(Image: Wall Street Journal)

Correction: HVAC Controller Setup

2010-08-23T23:16:00.004-07:00

"HVAC Controllers" section of the Configuration Guide was missing a slide - thanks to KF for pointing that out.

Fixed.

So what is it that you really wanted, but were afraid to ask?

2010-08-20T14:24:00.003-07:00

Google has just released yet another useful tool - the public version of their Product Ideas.
Here's an experimental form I created for us all:

What do you need that we don't do?

Missing a feature? Something doesn't work right? Don't like something? Speak up. 'Cause if we can't hear you, we can't make you comfortable. Which is the reason we're here for.

SO Override HOWTO

2010-08-18T17:55:00.010-07:00

Since I started eating my own dog food (but more about that later), I've met with the same problem many of other DZ users already have: the fact that system is not quite that accessible. Easy to control, yes, but not accessible. You can't just push a button passing by the thermostat in the hallway.

And the worst situation you may find yourself in is when you're asleep or away, and someone in the house wants things warmer or colder. Oh no, you don't want that (yeah, and that tooth had to be removed anyway).

But there is a solution.

Granted, totally ugly, but totally dependable.

How It Works

When you connect the relay board, you connect it not directly to HVAC cable or the unit itself, but as a piggyback to an existing thermostat. Let's consider RTH7500 (above) as an example.

Determine Wiring Scheme

Find the manual for your thermostat (here's a link to RTH7500 manual). Find the diagram for your specific installation (mine is on page 10, "Connect wires: Heat Pump").

Thus, you now know what wires to connect. For the example above I needed red, orange, yellow and green.

Careful! your HVAC installer may have used different colors, you have to look at the markings, not at the wire color!

Get yourself a piece of thermostat cable, or just find appropriate wires.

Connect the relay board

Red wire is the common wire, connect it to all "common" contacts. Connect other wires as appropriate.

Caveats

There are two common thermostat connection schemes - (white and yellow) vs. (yellow or white and orange) or (yellow or white and blue). Orange and blue wires are mode selectors - you need to know which exactly is the scheme your thermostat uses. For example, RTH7500 uses yellow plus orange ("energize to cool") and I connected it to NC contacts, since most of the year the thermostat is in cooling mode. Your mileage may vary.

Congratulations, you're done

So how does all this help you? Simple.

First of all, you set the thermostat much higher (assuming cooling mode) than it is necessary (if you take a look at the big picture, you'll see that the thermostat is set to 90°F) and set it to permanent hold. Then when you're not around and there is a desperate need to change settings, all that needs to be done is

Press the "Use Schedule" button (or the equivalent);
(optional) Disconnect the power to the relay board.

Added benefit is that whenever anyone is compelled to do so, the home climate will return to abominable state it was before, and the temptation will disappear for a long time.

PS: I am working on a more permanent solution, right now.

DZ 3.6.2 Release Is Out

2010-08-16T20:08:00.003-07:00

Download from SourceForge
Download from Google Code
Download from Ohloh
Get source code from Subversion
Get the hardware and start enjoying your home

Changes since 3.6.1

This is a maintenance release.

Many objects' reflections in JMX are now less cryptic and more usable;
XBeeDeviceFactory now properly reflects in JMX;
XBee deices not present at startup will now be discovered as they arrive;
XBee sensors departing will be discovered within a specified timeout and corrective action will be taken.

Honeywell RTH7500: Long Term Verdict

2010-08-09T16:38:00.003-07:00

Surprisingly, the most annoying feature of this thermostat turned out to be lack of programmable hysteresis, a.k.a. deadband.

This particular one, installed in this particular location, allows runtimes as short as three bleeping minutes - whereas the time required to get into more or less efficient operating mode is no less than about five minutes for furnaces and about fifteen minutes for an A/C or a heatpump.

Likewise, there is no minimum run time protection (sometimes called short cycling protection).

In other words, this thermostat will make your unit work much less efficiently than it is designed to, and the only way to prevent that is to put the thermostat in a place where the temperature changes very, very slowly - like a closet or a thermally insulated box. Which is not quite that practical.

So, thumbs down, no go.

Likewise, if I ever have to select a thermostat again, I will pay particular attention to presence of programmable hysteresis and minimum run time.

DZ 3.6.1 Release Is Out

2010-08-06T00:54:00.004-07:00

Download from SourceForge
Download from Google Code
Download from Ohloh
Get source code from Subversion
Get the hardware and start enjoying your home

Changes since 3.6

New Features

XBee ZB hardware can now be used to read analog sensors. Read more...

Early Access: XBee Analog Sensors

2010-08-05T01:36:00.004-07:00

Subversion contains the driver for XBee ZB based temperature, humidity, pressure and any other imaginable kinds of analog sensors. Scaling is also supported, so different hardware sensors can be used.

Read the article on making the wireless sensor for more details on sensor design. Configuration guide is coming soon (there are caveats, hint: take a look at ConvertingSensor).

Around The World

2010-07-31T02:52:00.003-07:00

View DZ Installations in a larger map

Since project inception in 2001, quite a few people installed DZ in their houses. Somehow, I didn't think of visualizing the community until very recently - but now I'm working on rectifying the situation.

Above is the map of known DZ installations, updated with new information as it comes. For all you know, there may be someone next door to you that can help you with the process, should you require assistance.

DZ 3.6 Release Is Out

2010-07-31T02:08:00.004-07:00

Download from SourceForge
Download from Google Code
Download from Ohloh
Get source code from Subversion
Get the hardware and start enjoying your home

Changes since 3.5.3

New Features

XBee ZB hardware can now be used to control HVAC actuators. Read more...
Seed Depot's Relay Shield is supported, along with any other designs that utilize XBee's digital output functionality.

DZ 3.6 Release Is Out

2010-07-31T01:48:00.005-07:00

Download from SourceForge
Download from Google Code
Download from Ohloh
Get source code from Subversion
Get the hardware and start enjoying your home

Changes since 3.5.3

New Features

XBee ZB hardware can now be used to control HVAC actuators. Read more...
Seed Depot's Relay Shield is supported, along with any other designs that utilize XBee's digital output functionality.

Teaser: XBee Wireless Temperature Sensor

2010-07-30T23:10:00.005-07:00

Above: XB24-ZB with four TMP36 analog temperature sensors connected to XBee's analog inputs.

The reason four sensors are connected is: comparison and statistical analysis.

It remains to be seen how good or bad analog readings are, and how easy it is to compensate for these imperfections in software.

Credit

This design is based on a similar one, with a few minor differences:

TMP36 is used instead of LM34 (the only reason being that I had some spares laying around). Obviously, the result calculation is different. Wide selection of similar sensors (TMP35, TMP37, LM35), result would be just about the same, save for value recalculation;
Incidentally, this allowed to get rid of the voltage regulator because whereas LM34 requires +5V to +30V power, TMP36 is fine from +2.7V to +5.5V, hence, the same 3.3V power can be used to feed both XBee and TMP36;
Caveat is, at +70°C TMP36 output voltage reaches maximum allowable voltage for ZB series ADC, 1.2V. I don't think it's a problem because the intended usage is indoor temperature measurement, if your indoor temperature reaches +70°C, you'll have bigger problems to worry than a possibly damaged XBee. But keep this in mind if you're planning to use these sensors to monitor a temperature of, say, a water heater or air coming out from the furnace;
330Ohm resistor added to ASSOC LED to restrict the LED's operating current (might want to use 1K and higher if your LED is too bright for you).

More to come.

DZ XBee HOWTO

2010-07-29T11:18:00.008-07:00

Now that XBee is supported, let's see how to make it work.

Bill of Materials

XBee ZB low power ZigBee Module w/ chip antenna or similar (wire or external antenna, but that would probably be an overkill);
UartSB V2.2 or similar ("adapter" hereinafter). XBee Explorer Regulated or XBee Explorer USB will also work (WARNING: read the note on SeedStudio products);
Relay shield (4 relays).

I would highly recommend to buy an extra XBee radio and an adapter if you have never worked with XBees before - it'll save you a lot of grief because you'll be able to monitor the network status activity. You see, the relay shield doesn't come with network status and activity lights, so unfortunately, you'll be flying blind and will have to re-plug XBee modules into adapter every time you're not sure what is going on.

Hence, recommended quantities are - three XBee modules, two adapters and one relay shield (add extra XBee module + relay shield pairs if you have more than one HVAC unit, one pair per unit) - starting at $110.80 before shipping.

Minimum quantities - two XBee modules, one adapter and one relay shield ($73.90 before shipping).

Before you say that's expensive, think how much you will spend breaking walls to wire cables, then patching them back, texturing and painting. Not even talking about time spent on all that exciting work.

Keep in mind that some suppliers have high lead times - I've seen as high as two weeks.

Power

Note that the power supply is not included into the bill of materials. The relay shield requires 9V DC power - you either might have one handy already, buy a cheap one wherever you fancy, or just use a 9V battery (the relay shield has screw on contacts for that). I don't know yet how long the relay shield is going to last on a battery with normal HVAC usage pattern, will find out and report.

Setup

Countless XBee tutorials exist, so I'm going to skip this part - suffice to say, get your XBees lined up and talking to each other.

DZ specific XBee setup

You need to flash one XBee module (the one on the adapter) with the Coordinator API firmware (when you get familiar with X-CTU software, this will become self-explanatory). Make sure you read the module configuration and flash correct firmware. After you flash API firmware, it won't be possible to use a dumb terminal to control the XBee anymore (limitation of ZB series), so make sure you're done with setting up communications correctly before you do that - like I said, extra XBee and an adapter will help a lot from here on.

IMPORTANT: Make sure you set AP=2 and write changes. The reason for this is that xbee-api library used for low level communications doesn't work with AP=1, and fails to report when AP=1, or forcibly change the module state to AP=2.

Baud Rates

Don't bother changing the port speed from default 9600 baud. DZ is more than happy with that speed, but if you change it, you might run into trouble remembering what it is next time you try to connect to XBee via an adapter.

DZ Configuration

XBee devices are configured in exactly the same way as 1-Wire devices: using a device factory. Here's a snippet that will produce a working switch (0013A200.4062AC98 is the 64 bit hardware address of my XBee module plugged into the relay shield, substitute it with yours):


<bean id="device_factory"
class="net.sf.dz3.device.sensor.impl.xbee.XBeeDeviceFactory"
init-method="start">
<constructor-arg index="0" value="/dev/ttyUSB0"/>
</bean>
<bean id="switch_0013A200.4062AC98_0"
factory-bean="device_factory"
factory-method="getSwitch">
<constructor-arg value="0013A200.4062AC98:D0"/>
</bean>

There are four channels on the relay board used. Channel numbers are printed on the silk screen (look at the data sheet if in doubt).

NOTE: Relays are marked COM1 to COM4, but channels to access them correspond to actual XBee channels - D0 to D3. This is done so that all XBee digital outputs can be controlled - D0 to D8, and P0 to P3.

Congratulations, you're done

From here on, things are just as usual - use the reference to switch_0013A200.4062AC98_0 as you would have with a 1-Wire based device.

UPDATE: Adjusted description to match the improved channel addressing.

UPDATE: This article describes the switch setup, see the Teaser: XBee Wireless Temperature Sensor for information about sensor setup.

DIY Zoning

Competition: Nest: Let Me Try To Help

Competition: Nest: Three Weeks Later

Disclaimer

The Good

The Bad

The Ugly

It Is Not That Learning

Verdict

Afterword

DZ 3.6.5 Release Is Out

Changes since 3.6.4

Competition: Nest Learning Thermostat: Black Box Analysis

The Excellent

The Good

The Neutral

The Bad

The Ugly

The Verdict

Applicability

Competition: Nest Learning Thermostat: Teardown

C Wire-less Setup

Afterthought: Multi-zone Setup

Early Access: DZ on Android

Competition: Nest Learning Thermostat

THE GOOD

THE BAD

THE UGLY

THE UNKNOWN

Early Access: SwitchDamper

DZ 3.6.4 Release Is Out

Changes since 3.6.3

Open Letter to SeedStudio

Emme: The Vaporware of 2010? [Update: Yes]

DZ 3.6.3 Release Is Out

Changes since 3.6.2

Dilbert Creator Weighs In

Correction: HVAC Controller Setup

So what is it that you *really* wanted, but were afraid to ask?

SO Override HOWTO

How It Works

Determine Wiring Scheme

Connect the relay board

Caveats

Congratulations, you're done

DZ 3.6.2 Release Is Out

Changes since 3.6.1

Honeywell RTH7500: Long Term Verdict

DZ 3.6.1 Release Is Out

Changes since 3.6

New Features

Early Access: XBee Analog Sensors

Around The World

DZ 3.6 Release Is Out

Changes since 3.5.3

New Features

DZ 3.6 Release Is Out

Changes since 3.5.3

New Features

Teaser: XBee Wireless Temperature Sensor

Credit

DZ XBee HOWTO

Bill of Materials

Power

Setup

DZ specific XBee setup

Baud Rates

DZ Configuration

Congratulations, you're done

So what is it that you really wanted, but were afraid to ask?