Comment by noonespecial | Hacker News Reader

Comment by noonespecial | Hacker News Reader

I'm wondering about the installation part. It doesn't seem to me that the average user is just doing to go grab one and get it in himself.

I made my own computerized replacement for the thermostat in my house(1) and discovered that there were about 5 different possible wiring patterns depending on if you've got heat pumps, multi-stage, e-heat, gas, etc.

After much research I figured out how they are wired, how my house should be wired and... burned out a fuse on the circuit board inside the furnace because the original installer had switched 2 wires and just said "screw it" and left it that way.

I had to remove and trace the circuit board with my fluke meter just to get my AC back. Its one thing for rich guys building their smart-house in Tahoe to choose this, but quite another for Joe average to go grab one at Home Depot and take it home and get it going. Calling your "Nest dealer" to schedule an install just seems like a nonstarter for the added cost this will add to what already seems pretty high.

As a geek though, the wifi part seems pretty cool. As long as it was sufficiently open, it could have saved me a bunch of work making my own HVAC interface.(2)

(1) My philosophy was that I didn't need a "thermostat" at all. The computer that does all of the other smart-house stuff for me should control the temperature as well.

(2) Proliphix makes a pretty decent openly programmable WIFI enabled thermostat but they cost around $600.

Your experience is highly atypical in most of the US.

The common setup is a single-stage heat/cool installation with 4 color-coded wires.

It's all low-voltage (24VAC) and the biggest problem most people run into is an older 2-wire setup (single-stage heat only), where the programmable thermostat can't be vampire powered from the circuit and either cuts out when it clicks the relay on to fire the furnace, or simply needs to be a battery-powered unit.

With all the eco-stuff and increased heating costs, installation of programmable thermostats by low-skilled homeowners is actually pretty common.

I have a OmniStat for my house, about $300, nice standalone thermostat with published serial protocol.

If you have an Omni security automation system to go with it you get IP access (again published protocol with a few iPhone apps) and the Thermostat can change temp based on security system state(away, night, etc.) or you can write automation code on the Omni to do whatever or use the IP protocol to do eve more from a real computer.

You don't want PC controlling the A/C directly, the OmniStat will continue to function without it's smarter controllers if need be, same with security, thats why I like my Omni system, it's a rock solid "lower brain stem" for my house while the PC is the "higher brain functions" that can go offline if need be without too much disruption.

http://homeauto.com/Products/Omnistat/Omnistat2Products.asp

Supports 2-stage cool/ 3-stage heat too, but really needs a common wire for power, no batteries.

So, how do the current thermostats get installed?

Off hand, I'd guess that the contractor who builds the house puts in the cheapest thing he can find, it works until it breaks and the HVAC guys get called "cuz the heat's broke". If a new thermostat is required, the cycle begins again.

If this is indeed the case, then its no surprise that thermostats are the most boring, user unfriendly things imaginable because they are more or less universally selected by price alone.

Home depot commits to much aisle space to programmable thermostats for them to simply be a new build or even a contractor replacement.

Anecdotally I certainly know several folks who have DIY'ed programmable thermostats into their homes.

The rumor I've heard is that you just connect it up however you want and it "magically" figures out the wiring for you.

Very cool. Mind sharing some details? Did you blog it? What kind of hardware did you use? How did you figure out how/what to do? What other "smart-house stuff" did you come up with?

I'm also waiting for more details. I was thinking of building such a thermostat myself so ...

Sadly I didn't blog it or even take pictures. I didn't set out with the "this is going to be an awesome project" geek-out mentality. I started small and it kind of accreted over about a year.

Main computer: Embedded linux platform called "Soekris Net4801". http://soekris.com/products/net4801.html

Linux Distro: "Voyage" Readonly embedded. http://linux.voyage.hk/

Lighting controls were Insteon from smarthome.com.(1)

I made one of these with arduino and a servo for the front door and linked it with xbee radios. http://hackaday.com/2011/06/30/diy-servo-activated-door-lock...

My HVAC interface was a 5-wire (we had heat-pump and e-heat) so I made a relay board that was controlled by arduino that ran off the 24v supplied by the furnace. There are common wire colors that are industry standard. Mine were installed wrong causing many headaches.

(1) Oh hey! look. They've got a selction of insteon compatible and wifi thermostats now! All for less than $200! Nice.

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