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Controlling Heating/Cooling on a Complex Schedule?
Controlio asks: "I've just replaced my furnace, air conditioner, and humidifier last week, in a house that I am rebuilding almost completely from the studs. With the outrageous cost of heating oil, I looked at saving some money by installing a programmable thermostat. However, my work schedule is too complex for most programmable thermostats. The one benefit I have is knowing my schedule a month or two in advance. So, the most practical option seems to have some sort of computer-controlled system that can accept calendar-based setpoints. This would also allow me the opportunity to VNC to the computer from work and change the schedule, in case of last-minute scheduling changes. The ideal solution would be able to control the heat and air conditioner, plus have the ability to do humidity setpoints (though it's not required). Also a system that could control two furnaces would be beneficial, since I plan on installing a heater in my garage this year. Does anyone know any hardware and software combination available to accomplish this?"
As sombody who's doing the same thing to a house,(So far I've cleaned up a fuel oil spill, insulated, replaced all the plumbing, the furnace, the windows (22 new construction windows... Ugh.), the bathrooms, fireplace enclosures, siding, most of the interior trim, and refinished the wood floors), first let me congratulate you and (if you're doing the work yourself) give my condolences for the loss of all your free time from now on.
The pickings are slim, and short of a multi-thousand dollar (probably more than you paid for your furnace, and certainly more than you'll save in heating costs over the next five years from the programibility) home automation system, you're not going to find anything remotely suitable for what you described. Even then it's not going to be as flexible or open as you're hoping. You can build something yourself, but there are three things you should remember.
First, you use the most fuel transitioning from your low temperature setting to the high temperature setting. You don't want the low to be too much lower than the high or you'll actually increase consumption, and you don't want to transition too many times per day.
Second, the more complex you make your program the less change you'll notice in usage. Complexity provides deminishing returns. (At least it should if your house is insulated properly).
Lastly, and absolutly most important is that you never, ever want your thermostat to fail. As sombody who has just replaced all the plumbing in a two story house, and delt with the concequences of 4' of water in a basement (happened before I bought the house... Got me a good deal.) take my word for it when I say you don't want to do that. Especially if you have oil heat. The bottom rusting out of your oil tank is not fun for anybody. So if you want to make it programable from your computer, that's fine, but make sure it can still turn your heat on and off without your computer, or that you have a secondary manual thermostat that won't let the temperature drop below 50.
When it comes right down to it though, every ounce of effort and every dollar beyond $100 you spend on this would probably be better spent on insulating. There are some great thermostats off the shelf at home depot like places that have four or five week long programming sets. Get one of those, and on your way out the door every morning, or every monday, pick the program that fits your day.
End result was a $1500 ONE MONTH electricity bill.
I'll tell you later about the large sized gas stove requiring a commercial grade Halon fire exstinguisher system. HA HA HA.
..........FULL STOP.
Excuse me -- you're a mammal. You can survive if you come home, the thermostat hasn't kicked in yet and you need to manually turn the heat up and wear a sweater for ten minutes. I'm glad you at least realize you can tolerate some marginal deviation in humidity.
I know energy is damn expensive these days, but do you really need to adjust it that often? Do you think you'd really save enough to cover the cost of such a complex system by fine-tuning that precicely? Perhaps I'm misinterpreting your needs but if I were in your shoes, I'd go over my schedule and find some common points at which to set temperatures and leave it at that for the period of your known schedule, if that is possible. Just pick the programmable thermostat to fit those needs. I'd go nuts trying to fine tune a system as you're envisioning.
As for the garage, if you're not going to spend every day in there, I'd suggest a generic theremostat or even a power switch on the furnace. Just turn it on before you want to work in there. If you plan to heat it, you plan to insulate it, so it should heat pretty quickly.
Maybe it's just me (I'm just a geeky farmer), but I just don't see the point of a complex system.
Wow this sounds like a lot of work. I think I'll stick to my current "system":
1. Too chilly? Turn on the heater for a few minutes.
2. Too hot? Open the windows/turn on a fan.
But you're right - energy is getting expensive. I just broke $100 for gas/electricity last month.
~~~~~~~
"You are not remembered for doing what is expected of you." - Atul Chitnis
In the spirit of what people idealize /. to be, I present the URL to an opensource project called DIY Zoning (that is, Do-It-Yourself for those who live in an apartment). It is a very well designed website with links to best practices and pointers to basic parts and the sourceforge-based software. From the site:
This would also allow me the opportunity to VNC to the computer from work and change the schedule, in case of last-minute scheduling changes.
Well, it's clear that you've alredy found a solution, and now you're just searching for a problem to solve with it.
However, I really think you should step back and thought about the problem you're trying to solve. If you weren't so hung up on the technology, you'd realize that a thermostat running the X Window System would probably work just as well.
Yes, it's clear to me that your thermostat should run FreeBSD.
Why not just manually change things manually? Any disconfort tempature-wise is just something you have to accept for saving $.
Think how much a system like this is going to cost and how much in man-hours its going to set up. Then factor in the time and effort to fine-tune it, adjust it on an on going basis. Is it really worth it to save on the heating bills?
The surprise isn't how often we make bad choices; the surprise is how seldom they defeat us.
If I were doing something like this I'd be looking at micro PLC's. Besides giving you the temperature control capability you are looking for they offer the potential to do a lot of of other home automation jobs.
If you don't mind writing a script or two, you're not looking at something that's impossible on a lighter budget. The X10 standard is actually pretty sucky, but I put it in my old house and it worked out okay. Raised the value of the house roughy 10X what I put into it, too. Anyway, check out smarthome.com, specifically this product.
Disclaimer: I haven't used this specific product. I have used just about every other X10 product, though, and the smarthome site does a pretty good job of explaining how to set things up. I used to use a wireless transmitter on my Linux box and some scripts put together called "firecracker" to communicate. Simple cron jobs did the rest. If I recall, I also had a device that transmitted/received from a serial port to the power lines directly, but I don't know if they still sell those or not.
If you really want to control your heat and A/C this way, I STRONGLY suggest taking lots of temperature samples of where things are at and ensuring you aren't wasting energy because of poor control systems. One mistake in code and your bills will go wild.
Long, cute, or funny Sigs are just another form of over compensation, used by geeks, nerdz, etc.
If you're replacing the furnace and tearing the house apart as much as you say, why not switch to electric or radiant heating? The difference between the cost of electricity and heating oil will lower your heating costs more than a computer-controlled thermostate ever would.
I recently replaced the thermostat in my house with a programmable. The thermostat that I purhcased (the Hunter Fan model 44760) http://www.hunterfan.com/prodSum.php?pid=20&pType= thermo&sType=4 had an ethernet port on the back of it. IIRC, it mentioned somethings about future development, and I haven't tried it, but you might check it out. A little hacking and you might come up with something.
Using the Freedom of Speech while I still have it.
Now, I am just curious.
:-)
How much insulation did you use for your roof, walls and floors?
Here in Denmark the houses are normally rather well insulated and made with brick walls or concrete walls. Therefore the time-constant is often so high, that changing the temperature hour by hour normally doesnt make any sense at all. In our house we have floor heating with tubes in the concrete floor and it takes several hours to change the temperature. Its good for keeping the feet warm in a cold winters day
...in the agriculture (poultry houses for instance) and greenhouse industry. You'll need to research there for it I don't recall brand names off the top of my head right this second, but should be easy enough to find examples of. They have systems that are both automatic programmable there at the dedicated computer and remote controlled over the internet for monitoring and adjusting, heating,cooling, humidity, etc. Warning: it's spendy stuff, but will do what you want. I also really doubt any of the software is FOSS, although it should be.
I'll tell you later about the large sized gas stove requiring a commercial grade Halon fire exstinguisher system. HA HA HA.
That I've got to say BS. While many commercial stoves have a fire extinguisher system, halon is used when you have a lot of delicate electronics (isolated server room). I can't see how a gas stove has a lot of delicate electronics. A conventional dry chemical or CO2 fire extinguisher would be fine.
What's more, halon is toxic and very expensive. Only an idiot would use halon in a kitchen where people are usually found.
This is how one person did it in UK: http://www.drobe.co.uk/features/artifact1467.html
Everything you need to manage your schedule is a d/a board and crontab on linux/Unix.
X10, and a couple of other companies, make X10-type protocol thermostats. X10's appears to be just a setback controller, but it's only about $20. A company called RCS seems to make a full-fledged X10-controlled thermostat for around $250.
Yeah, they were obnoxious with their popup stuff, but their products work well enough, and there's other people who make boxes that work over the protocol. Fire up a linux box with a Firecracker on it, and use at/cron/whatever ot control your thermostat. Or go all the way and do the whole home automation deal.
Google is your friend. Search for x10 and thermostat, X10's are near the top and there's a couple of links to the RCS version in the first page.
This space for rent. Call 1-800-STEAK4U
If fuel energy bills are a big factor, why not take a look at energy-efficient heat-pumping solutions as described here?
Granted, the installation costs are generally higher, to secure lower running costs, but you could find that the balance works out ok in timescales in which you are interested.
-wb-
This might get ugly, especially if you don't have that much experience with hardware/software programming, but you could make something yourself. Dick around with the thermostat for a while until you figure out how you can control it with a relay. Then look in designing and programming some software to control it (add on or parallel port). This is quickly sounding like a geek project, but if you have the time and interest it could be fun and cost efficient. You might also want to look into any off the shelf X11 components you can find to help you out or provide insight into alternative ideas.
Sorry, I meant X10, not X11. And one more thing to add, what about adding more heating zones so you only heat the parts of the house you need too. Older homes with one heating zone can waste a lot of money whereas if you only need a few rooms warm and toasty and the others at around 60, you could save some more money.
If the original poster is from America, most likely his house is wood from the sill up; wood is still relatively cheap in the US. Concrete construction in single family homes is much more common in Europe than America, and plumbing/heating systems in Europe reflect that difference.
Insulation technology for wooden houses has improved immensely in the last 20 years, and it's probably a better investment of time and money to figure out how best to button up the house, and get a nice programmable thermostat that will let you change between some pre-programmed schedules. Or come up with a system (sticknotes?) that will remind you to turn the manual thermostat down when you leave the house.
I work in the business of doing this type of control in large buildings. Typical home thermostats are grossly inadequate for larger buildings. The type of products we manufacture allow any kind of custom programming you can dream up and although the "language" is something like BASIC, I have seen products that can execute Python scripts (see original story comment).
:)
Normally this stuff isn't used in residential buildings because of the cost and complexity, but that didn't stop me.
Drop me an email at greg@.@holloway@gmail@.@com (with a few less at's) if you'd like to know more. The trouble is that at regular prices, you'd be over $1000 in no time, which takes a lot of energy saving to pay back. However, the neat thing is the "predictive" things that can be done with a bit of intelligence. For example, my furnace won't start today if yesterday afternoon was warm.
Oh and yes, you would be able to access your home controls over the Internet.
GRH
You're right, commercial stoves just use a conventional dry chemical, makes one hell of a mess if it discharges though.
I put in a programmable thermostat about 8 yrs ago (in conjnction with a whole new heat pump system). It allows for 4 different settings for each day of the week. But because of spouse/kids in and out all the time, I pretty much just keep it at one setting. Heat to 67-68 in the winter, cool to 74-73 in the summer. It is good for reminding me to change the filter, though.
I also have a workshop/computer room in the garage, and have very simple method for turning the heater on out there. 5 minutes before I need it, I plug the heater in. Free, easy, and can't fail.
A very simple solution with some safety built in would be this: Use two thermostats. Set one for the 'home' temerature and one for the 'away/sleep' temperature. Use a relay with SPDT contacts, controlled by the computer/timer/whatever, to select which thermostat is on-line.
This will not allow for remote re-setting of setpoints, but it will allow you to select which of two preset setpoints is active at any given time. Additionally, the failure mode will be to have one of the two thermostats on-line, causing this system never to take your furnace completely off-line, thus removing the risk of frozen plumbing.
www.wavefront-av.com
I'd worry more about internal humidity than internal temperature, since humidity affects us more as far as comfort.
"...a whole house humidifier built into your ducts will never get the humidity up to your requested setting before the furnace shuts off..."
Depends on the humidifier and the size of the house. Most whole-house humidifiers are of the evaporative style, while an ultrasonic humidifier would be more rapid.
http://www.kmc-controls.com/
These guys make a many different sized PLCs with a very easy to use programming language and excellent control features.
For a house with a radiant floor system, a forced air system, a complex schedule, and internet access. You could probably get away with the item they call the weblite. This board has 8 inputs and 8 outputs. Inputs can be 0-20ma, resistor, or contacts. You will also need a Wincontrol XL Plus software for programming. This controller will talk to as many other controllers as you could possibly want.
Now, all this is great, except the system you describe is vary complicated with overlapping systems that solve the same problem in very different ways.
A radiant floor system is designed for steady state control, setbacks are counter productive because the huge lag time to set point changes.
A forced air system responds very well to set back set points because it's actually more efficent because the furnace does not reach it's rated efficency until it has been running continuously for at least 30 minutes. Direct expansion cooling systems take 10-15 minutes to reach their efficency rating.
Programming in an adaptive recovery program is trivial compared to almost any pointer search you've ever programmed. This stuff isn't hard, but mistakes can be vary expensive. :)
These systems can just as easily control your sprinkler system, outdoor lighting, your garage heat system, etc.
If you have multiple zones, I'd probably recommend using a seperate controller for each zone rather than just getting a larger central controller, it makes the wiring easier and can still be controlled from a single computer.
For remote access, the weblite has a small, basic web server that allows you to adjust setpoints directly, as well as set schedules, and look at all your inputs and output directly. Heck, it's even pretty easy to run the fan for a humidifier cycle even if the house doesn't need the heat. If you have a PC running VNC already, you could skip the weblite and just go with the basic lanlite (10baset) or the 5801 (serial) and just run the webcontrol software on that PC. Could save some money.
Going with the 5801 controller has the added benifit of direct connection the 1181 netsensor, with a very nice display, universal programable buttons, integrated humidity sensor, and they you don't need the plus version of the software. Drawback is that you'll need an RS-485 to usb/rs232 converter.
It's also very easy to adjust the humidty setpoint based on outside air temperature. With integrated enthalpy and dewpoint functions, you could even use a commercial style economizer for low ambient cooling calls. Outputs can be analog as well as digital so it becomes trivial to control modulating motors.
I really love this kind of work and I hope you find it as rewarding as I do. Do realize that it's next to impossible to make your money back on these kinds of controls unless you actually plan on finishing the payments on that 30 year note. If you can live with 4 temps per day on a seven day schedule, the honeywell vision pro 8000 thermostat is a much more cost effective option.
I've been thinking of the same thing myself, except I've decided against it (I'll go into why later).
While I've had OK results with X-10 equipment (they were a good company until they started their popunder/spam/camera obsession. rather than updating their products for modern times, they went on an annoying advertising spree. The end result is that Smarthome's Insteon is going to kick X-10's ass in its original market.), I would go with something more robust/flexible than X-10 now. Smarthome (www.smarhome.com), mentioned in a few posts here, has an RS-485 thermostat available. The documentation seems to indicate that their $100ish thermostat requires a $200+ controller, but I can't be sure of that. You may be able to get away with a PC and a $30-50 RS-232 to RS-485 converter. (The $200 controller appeared to be meant for a PC-less environment.)
That said, a few other people have suggested simply working on upgrading your insulation. Within a week of moving to this apartment, I realized the value insulation has. I can turn my heater completely off and the temp will never go below 65 degrees Fahrenheit (heated by leakage from the neighbors). Huge difference from my parents' house, which costs $100-200/month to heat even though they have the temperature at insanely cold levels. The house in question isnt' even that old - it's only 15ish year old.
As nice as a computer-controlled thermostat is, good insulation is even better.
retrorocket.o not found, launch anyway?
Dick around with the thermostat for a while until you figure out how you can control it with a relay. Then look in designing and programming some software to control it (add on or parallel port).
Hack the existing thermostat? Relays shorting buttons. My Honeywell CT3500 has up and down arrows for a temporary (2 hour) override of the program.
To replace the thermostat, would be very easy to control the furnace and AC by computer. Most systems use between 2 and 5 wires on a 24VAC control system.
Colors of the wires are not standardized, their names (on the thermostat or furnace) are. R is common, Y is cool, W is heat. G and B (if memory serves) are fan. Multistage systems use W1, W2, W3 and Y1, Y2, Y3 as "stages" of heat or AC. Some systems keep the heat and the AC split, so you might have Rc and Rh, where Rh is common for heat and Rc is common for cooling.
To get heat, connect R (or Rh) to W - the furnace will go through its startup rituals and fire. To get air conditioning, connect R (or Rc) to Y. Always a good idea to use an SPDT relay or switch to select mode; that way, it should be impossible for heating and cooling to be on at the same time. G and B are connected to each other to force the blower fan to run; otherwise, it's controlled by the furnace.
Make sure you don't cycle the heating and cooling too fast; usually no more than 2 cycles an hour, but check with your furnace manufacturer. Gas and oil furnaces operate most efficiently when they're running nearly continuously - which is where multistage furnaces come in.
Fire and Meat. Yummy.
How about this instead:
;).
:).
;).
0) get better insulation.
1) get a cluster of Intel PCs (especially those that use 250W or more of power under load). A slashdotter can always find a way to use more computers
2) run lm_sensors on the PCs - this is how you get your temperature readings.
3) Depending on the time, date, derived ambient temperature and other customizable info, decide whether to run CPU intensive jobs on your computers.
Voila - temperature control
Notes:
There are many useful CPU intensive jobs you can run. Go look for them.
Wake-on-LAN can be useful.
Controlling non-heatpump heating with some expensive home automation rig or furnace seems as silly as my suggestion
Heck my proposal wastes less energy- after all you could say the energy is used twice. Computers are cheap compared to some of the stuff proposed here.
> However, my work schedule is too complex for most programmable thermostats
"Most"?
Why restrict yourself to the ones that don't work? Why not buy one of the other ones for which your schedule is NOT too comples???
Sigh...
Max.
THe perfect keyboard for you would be the IBM Model M! Durable, terrific feel and......really compact...
I love NetHack.
The HAI Omni security systems have really good integration with the HAI Omnistat programable thermostats. The Omni security systems have a very simple macro language for setting up commands based on security, timed, user input or security sensors and the result can be a change in thermostat settings. For example we have ours programmed to setback the thermostat to 60 after 10pm (11pm on weekends). After 5am if the motion sensor in the bathroom triggers (indicating I stumbled into the bathroom for a shower) the systems runs a series of "Wake up" events, including resetting the thermostat to 68. Once the last person leaves the house and arms the security system the thermostat sets back to 60 again until someone returns from work.
Since you have the walls open now is an excellent time to run wire for a hardwired security system (which are a little lower maintainence and cheaper than wireless systems). Having a monitored security system (with a sign out front) is a relatively good way to prevent breakins.
The security system can also be programmed to call you or the monitoring system if the inside temp drops below 45 degrees and you can add sensors for whatever suits you. (How about a water sensor by the washer/dryer and in the basement? Or a fuel level sensor on the oil tank?)
There is also the Elk M line of systems which lack direct thermostat intagration (although I think they too can control the Omni series of thermostats over a RS232 link). The Elk systems are much cheaper than the HAI and have support for Proximity cards for disarming/door unlocking but I have no experience with them. Both systems are available from Smarthome or other online retailers.
As someone else noted, setting back a thermostat will usually save money, but only if the thermostat is setback for several hours (the exact amount depends on how well your house is insulated and how much thermal mass it contains). You may want to experiment while watching some form of "runtime" meter attached to the furnace or thermostat.
"A good, high-quality oil or gas furnace will start at 90% efficient and work up from there"
Funny how you include logistics cost, but then don't mention them with your on-site furnace. Plus there's the cost of processing the fuel. Having an on-site furnance isn't going to change that.
"As for suggesting radiant heat as an alternative to oil, that is the same logical fallacy as suggesting a car instead of a Subaru. Radiant heat uses electricity, oil, gas, coal, or whatever else fuels your boiler."
True, however resistive heating has two properties that are in it's favour. One the heat is generated were it's needed (in your floor with embedded coils) which means that it heats the floor and people better than sytems which heat at a central point and then transfer the heat were it's needed. It's also a simplier sytem, less to go wrong, and cost.
Note well that I haven't mentioned on-site energy generation (i.e. solar, wind, biomass) which changes the argument somewhat.
When my parents built the addition onto their house in 1980, electric baseboard heaters were installed (the house is on a slab with no way (at that time) of tying into the central heating duct system (which was set into the slab). The first month they used it (January near Chicago) they got the lowest electric bill they had ever received. The next month was the highest they ever had.
In the first month, the electricty usage was so great that it had "flipped" the meter so that when the meter was read, it was only a little above the previous month's reading. The next month was warmer and the heater didn't need to run as much. The heaters failed to flip the meter that month. They never used them again.
On a sidenote (alright, so the whole post was a sidenote), when the furnace was replaced, the contractor added ductwork to the expansion (in the ceiling) and rigged up the blower system to utilize the existing ductwork and the new ductwork. This may not sound like a big deal, but furnaces come in two flavors of blowers, they blow into the ceiling or they blow into the floor. The old ducts were in the floor, the new ducts were in the ceiling, and both needed to be used by one furnace.
Rather than micromanage the thermostat schedule, a low-maintenance alternative would be motion or occupancy sensors in some key locations.
If you're home, you'll trigger them and get heat, if you're not then have it default to 55F or whatever is good for your area.
But as others have said, insulation and weatherproofing may be a better investment than a geeky control system. When the furnace kicks on it's not just heating you at that moment, it's got to burn a lot of fuel make up for being off for N hours.
(And if you have a 2-stage burner or dual-fuel system of some kind, the switchover to the 2nd stage or 2nd fuel is worse than just leaving the thermostat at 68F all the time.)
I've looked at controlling the heat with programmable thermostats and so on, but it's either a) too much work, or b) too expensive.
Enter phidgets (www.phidgets.com). I've never used them, but they look like just the thing. I discovered them on an carputer forum (mp3car.com) a few weeks ago.
Cheap, USB, linux-compatible. What more could you wish for?
Temperature sensors and everything.
I'm going to leave the manual thermostat at 45-50 degrees, and add a relay (phidgets have relay controls!) to the thermostat circuit to turn the furnace on and off.
Bonus points for adding a bluetooth listener to turn the furnace on when I walk in the door in the evening.
cej102937
I use a HAI Omnistat RC-80 computer controllable thermostat (available here for about $160, or cheaper on ebay), a serial cable (made from CAT 5 cable), and some software I wrote (available here) for computer control.
The thermostat operates on it's own (no risk of freezing pipes if the software chokes), but you can reprogram it through the serial port, including changing mode (heat/cool/off), temperature set point (seperate for heat and cool), the schedule for automatic setback for weekdays/saturday/sunday (4 times per day), or setting the clock. You can also read all the settings/current temperature from the thermostat. It even keeps track of how long the heater/AC has been on for the past week. I have a cron job that reads this everynight, does a difference based on the last nights reading, and generates graphs using rrdtool. (Example here).
With a little bit of procmail processing, I can send my server at home to get status information, or turn the heat up before I drive home from work. If you want to do dual zone, you can just get a second thermostat, you can put multiple thermostats on the same serial cable (I haven't tested that though). If you need more complex scheduling, a cron job can take care of that, and just reprogram the thermostat daily, or constantly.
I gotta agree with the AC here... this would be a really strange application for Halon. Halon's chief advantages are that it leaves no residue and acts very quickly. The chief disadvantage is that it'll rapidly kill anyone who doesn't get out of the room, because it eliminates most of the available oxygen.
So Halon would work fine for fire suppression, but it'd sorta fail the life-safety aspect of the residential fire code. In residential applications you can expect to have children, disabled, and other folks who may not be able to understand an alarm or properly respond by evacuating. Residential fire codes need to take this into account, and they focus on life-safety more than structure-safety. (When it comes right down to it, sacrificing the structure to buy a few extra minutes of evacuation time is a good trade in a residential application.) So I'm thinking no fire code would require Halon in a residential setting, and I'd bet it's not even allowed in most residential applications.
Probably what code required was an Ansul dry chemical fire suppression system. Ansul is very effective, but it ain't cheap and makes a frightful mess when its Rube Goldberg-ish mechanical trigger goes off. A discharge would mean hours of cleanup work, kissing goodbye any food in unsealed containers in the whole kitchen or pantry, and calling a contractor to re-set the system before you could operate your range again... but it wouldn't risk killing anyone.
There also exist water-spray systems that properly installed can actually work on grease fires, but that amount of water in a home kitchen may be even more disastrous than Ansul. (Got floor drain? Plus, the key words are "properly installed". Water on a grease fire normally results in an explosion. I've seen video of a bad water dump on a hot fryer... Trust me, you do not want to try that at home.)
There's another thing about commercial gas ranges in home kitchens that your avereage DIYer may not consider. Modern houses (or clever remodels) tend to be highly-insulated and relatively draft-free. Commerical ranges have gawdawfully-huge gas burners that produce a great deal of CO and CO2. There better be a damn good source of combustion air and someplace for all those exhaust gasses to go, or your first fancy dinner party will really knock 'em dead.
With reasonable men I will reason; with humane men I will plead; but to tyrants I will give no quarter. -- William Lloyd
1) Presumably you've looked into 'home automation' and suchlike? I've never used it, but I understand there is a home automation standard known as X10. A quick search for "X10 HVAC" reveals there's a few about.
2) You talk about VNCing in from work. A system that needs a PC on 24/7 probably won't lead to a net energy saving, since your computer is probably consuming more than 100W any time it's on. If you would have your computer on anyway, consider turning it off and getting a $10/month shell account somewhere for your server needs - that may well represent an overall saving for you.
3) Captive tappets rock my world. No stupid digital timer with a tedious 3-button interface, and much better than most other designs of mechanical timer. Not that appliccable to your needs, I know, but I thought I'd mention them anyway.
4) Get a radio-controlled system! I always thought they were a bad idea since you have the bother of batteries, but as I recently discovered, it means you don't have to mount the control unit anywhere, meaning you can keep it right by the door, or on a convenient shelf. Beats going into some upstairs cupboard to set things up - especially if you're changing it regularly.
Michael
"Goodness me, how unlike the FBI to abuse the trust of the American public." -- The Onion
An even better way to reduce heating/cooling costs is to ensure that your renovations make your house as energy efficient as possible - look at insulation, air flow, passive solar considerations for shade in summer and exposure in winter. The more you do now to design a home that will maintain even temperatures on it's own, the less you need to intervene with heaters and air-con.
Sara
Designer, Gamer, Macgrrl in an XP World
You're absolutely correct that deeper setbacks are (barring a few edge cases) always more energy efficient, so long as the efficiency of the heater doesn't vary. Most don't vary, other than being a bit more efficient when they have longer runtimes (stops and starts are a smidge less efficient). The exception is heat pumps.
Heat pumps should always be used with a thermostat designed for use with a heat pump. The reason is that heat pumps have an "aux heat" mode that they use when they need to change the temp in a hurry. Regular setback thermostats just change the temp and tell the heater to heat (binary). This causes a heat pump to kick in the aux heat, which in many cases is resistive electric (i.e. $$$$). Thermostats designed for heat pumps change the setpoint early and slowly, a degree or so at a time, so the heat pump hopefully never needs to kick in aux heat mode. (Modern heat pumps are 250-350% efficient, compared to 100% for resistive.)
If you manually bump a thermostat for a heat pump up by more than around 2 degrees, it will normally kick in aux heat until the temp has reached the setting. So manually doing setbacks or frequently increasing the temp by a bunch over the programmed value will be more expensive than letting the program run.
** The edge cases mentioned are things like condensation, pipes in danger of freezing in really deep setbacks, or where temp changes cause cracks to open in caulk, etc.
I work for an industrial HVAC "controls" company where we charge thousands of dollars to do the controls for hospitals, office buildings, schools, etc. Facilities like those can recover the money in a few years and start saving money over the lifetime of the system because they're so damn huge and generally waste large amounts of energy.
Setting up a residential home automation system is really just a giant waste of your time and money unless you live in some kind of huge 10+ bedroom mansion in the desert or near the north pole. For residential homes, look into some of the X-10 type sensors and thermostats (www.smarthome.com)... but it's mostly just for having neat toys rather than saving any kind of real money.
Perhaps this internet enabled thermostat is what you're looking for.
Does anyone have a pointer to a web site or book that helps you calculate the average R-value of a house? Seems like it would be not tooo hard to do if you had the right rules. For instance, a table (set of tables really) or web site should be able to correlate effective house R-Value to indoor temperature change rate, average indoor temperature, average outdoor temperature. This is quite a few variables to measure at once, but basic measurements and formulas should be enough. With a few assumptions and repetition, it should be possible to roughly measure effective R-Value and see if there are be easy measures to improve the efficiency of your home. If your walls are R-18 and you measure your house to be effectively R-10, you have a lot of steps you could take before you had to worry about re-insulating your walls.
Even if you're stuck at low R-Value, you can at least compute theoretical cost savings with an ideal heating schedule. With this tool, you could also measure how much various fixes effect the over all R-Value of your house.
Today is all we really have. We should all live it well: it is our stepping stone to all of our tomorrows.
This looks perfect - exactly what I need. And the on/off hours tally allows me to do some real nice things like billing estimates and schedule optimization.
The only bummer is I can't see your software on sourceforge - it says no file packages found. But looking at the manual for the thermostat, it doesn't look too complicated to conjure something up.
Thanks!
There is a great bit of kit I am using in a conversion to do just this - called a webbrick. have a look at http://www.o2m8.com/ this thing has built in schedules, web configurable or you could use cron with python to control from your computer. It will fit in a standard consumer unit (din mountable) an is a doddle to set up initially, as well as being flexible if you want to have a more complex configuration.