Controlling Heating/Cooling on a Complex Schedule? 89
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?"
Nothing for sale in a reasonable price range... (Score:5, Insightful)
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.
Re:Nothing for sale in a reasonable price range... (Score:2)
Re:Nothing for sale in a reasonable price range... (Score:4, Informative)
Oh, one last thing. Your relative humidity setting should be a constant function of the outside temperature. Why? Otherwise you risk condensation, and condensation leads to rot and mold. Of course, if your house is insulated properly, a whole house humidifier built into your ducts will never get the humidity up to your requested setting before the furnace shuts off, but that's a whole different problem...
Re:Nothing for sale in a reasonable price range... (Score:2)
Here's one way how having a higher low-setting could save heating energy: at unoccupied temperature A, the furnace burns 1 unit of fuel per time unit. At unoccupied temperature B, which is higher than A, the furnace burns 1.1 units of fuel per time unit. During the transition period from unoccupied to occupied temperatures, the furnace burns 10 units of fuel per time unit. The transition period from A to occupied takes 100 time u
Re:Nothing for sale in a reasonable price range... (Score:1)
Which is an unusual analysis.. in a real system, assume a single stage setup, I expect the equipment would always be off or blowing on at full, always.
When heat is not called for, the equipment should be burning 0 units, whether maintaining unoccupied temperature A, or temperature B, it doesn't matter -- the system is idle most of the time.
Consider the case where Temperature A is equal to or less than the outside temperature. In this case, the system doesn't need to burn any fuel at all; which may
Re:Nothing for sale in a reasonable price range... (Score:3, Informative)
You *never* need to add more heat than escapes. And lower temperature-differential *always* means less heat escapes. End of discussion.
Re:Nothing for sale in a reasonable price range... (Score:2)
True, but is the amount of heat produced always directly proportional to the amount of fuel used? In other words, is the efficiency of the furnace a constant, or are some settings more efficient (in terms of heat per fuel) than others? The claim of a previous poster was that some furnaces have multiple settings: a "heat the place up real fast" setting that's less efficient and a "maintain constant temperature" setting that's more efficient.
If such furnaces
Re:Nothing for sale in a reasonable price range... (Score:2)
"always" is a tricky word. Most furnaces operate in off/full-power modus, which mean they are equally effective regardless, there's only one "on" mode, it's just a matter of how often this is used. heat/fuel should be fairly constant even for furnaces that don't operate lik
Re:Nothing for sale in a reasonable price range... (Score:2)
I consistenly get 10% savings when the weather is cold and it stays lo for at least 12 hours.
Simply put, the energy put into the system must equal the energy going out.
Now, to defend the other point of view... It is possible that older style furnaces lost some of their efficiency if they ran too long (not that they were ver
Re:Nothing for sale in a reasonable price range... (Score:3, Informative)
Re:Nothing for sale in a reasonable price range... (Score:2)
My prediction? Never. The electrical costs of running the PowerMac 24/7 will be between $11 and $20 a month depending on where you live, and the gas or oil savings will be that much or less.
Re:Nothing for sale in a reasonable price range... (Score:2)
That said, X10 is a pretty crappy home automation system.
Re:Nothing for sale in a reasonable price range... (Score:2)
Re:Nothing for sale in a reasonable price range... (Score:4, Insightful)
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.
Absolutely agree with you. My little trick, which I do whenever I'm installing a programmable thermostat, is to take the old mechanical thermostat and mount it in the utility room (or wherever else the majority of the plumbing is). Set the old thermostat to its lowest setting and connect it in parallel across the heating leads on the new thermostat (R-W wires only).
This way, if the new thermostat fails (ie. dead battery), the furnace will kick on before the pipes freeze. Would work doubly well if you've got your computer controlling the heat - even FreeBSD can crash from time to time.
Another issue - why not consider using small motion detectors to adjust the temperature? If there's no motion, you're either out or asleep, right?
Insulation is super-important; my house is 600 square feet (tiny WWII veteran's home) in Ottawa, Canada. Each exterior wall was 2x4 originally; when redrywalling a few portions, I've screwed 2x2s onto them to allow the use of 6" thick insulation. With the new windows and a load of fiberglass in the attic, my Trane XV90 rarely kicks on even in the winter; computers and household activities (cooking, etc) keep the house warm enough most of the time.
Aside: love my Honeywell CT3500. It's a simple 5-2 programmable.
Re:Nothing for sale in a reasonable price range... (Score:2)
Oh, but this is Norway where it's bone-cold, I hear you think. Only that's not really the best description of the west-coast. The
Re:Nothing for sale in a reasonable price range... (Score:2)
In response to mysidia, I'm glad you're on the same page I am. As I posted here [slashdot.org], I can end up spending a great deal of time away from the house - often I go on weekend road-trips or do double-duty and work 14-15 hours a day. That's a lot of wasted heating and coolin
Re:Nothing for sale in a reasonable price range... (Score:2)
Oft-repeated "wisdom" -- if you let the temperature fall too deeply, it'll cost more to re-heat than you saved in the first place.
This ignores the plain fact that this is physically impossible.
Re:Nothing for sale in a reasonable price range... (Score:2)
To keep the house feeling warm, you need to set the internal temperature higher if the internal surfaces have been allowed to cool down too far. Additionally, your thermostat will keep the heat on until it's warmed up the wall it's mounted on.
The amount of heat that escapes is, to a first aproximation, proportional to the temperature-differential between indoors and outdoors. (if that is 0, no heat is lost, if it's 60 degrees you wil
Re:Nothing for sale in a reasonable price range... (Score:2)
I have. At 12 hours, and cold weather, I use 10% less after the house has been at 55 instead of 65 (and yes... measurement is after house warms up).
Heat pumps are a special case (Score:2)
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 te
Re:Heat pumps are a special case (Score:2)
I do have a heat-pump. But it's a bit more controllable, it's got a separate termostat for the resistive heating, I can thus say: Go for 21 degC, but if we'd otherwise drop under 18 -- use the resistive heating.
Daytime, when I come from work the programming is with a bit of dif
To err is human, to really F up requires acomputer (Score:3, Funny)
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.
Re:To err is human, to really F up requires acompu (Score:2, Informative)
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
Re:To err is human, to really F up requires acompu (Score:1)
In the first month, the electricty usage was so great that it had "flipped" the meter so that when the meter was read, it w
Surely not Halon? (Score:2)
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 folk
Yikes!! (Score:1, Insightful)
Does it really need to be that complex? (Score:3, Insightful)
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.
Re:Does it really need to be that complex? (Score:3, Insightful)
Take a look at heat-pumping (Score:2)
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-
Re:Take a look at heat-pumping (Score:2)
My guess is that this happened beacuse of changes in humidity rather t
Way too much work (Score:3, Insightful)
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.
Re:Way too much work (Score:2)
energy is getting expensive. I just broke $100 for gas/electricity last month.
Hahahaha... Guess you're not in the snowbelt. :)
Re:Way too much work (Score:2)
DIY Zoning (Score:4, Informative)
In the spirit of what people idealize /. to be, I present the URL to an opensource project called DIY Zoning [sourceforge.net] (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:
Re:DIY Zoning (Score:2, Informative)
FreeBSD (Score:1, Troll)
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
Complexity (Score:2)
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?
Re:Complexity (Score:2)
I live in Michigan. I am not yet living in this house (still very much under construction and awaiting an electrical inspection) and I keep the house at 45 degrees when not being worked on... the lowest allowed by my thermostat. This is partly due to a few uninsulated walls and an underinsulated hole in my ceiling... read this post [slashdot.org] for details. Anyways, I got my gas bill for last month... for 9 or 10 wor
Re:Complexity (Score:2)
Think how much you make per hour. Think how much time you are going to spend setting up and maintaining the system. Think how much you will save in gas. Is it worth it?
Would it just be worth it to "suffer" with a cold house for a while because you want to save some $, rather than to go for a complex system?
Micro PLC (Score:2)
Got a programmer handy? (Score:3, Informative)
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.
Re:Got a programmer handy? (Score:2)
heating oil? (Score:1)
Re:heating oil? (Score:2)
I locked in my oil price at $2.04/gallon this year. I will burn on average about 1000 gallons, but this is due to windows needing to be replaced and other issues. Electric would be much more.
To reduce my consumption I did just purchase a cheap ($45) 7 day programable
Re:heating oil? (Score:2)
Re:heating oil? (Score:2)
http://www.armstrong-intl.com/common/allproductsca talog/thermostaticvalves.pdf [armstrong-intl.com]
Re:heating oil? (Score:5, Informative)
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.
Absolutely, 100% totally, completely incorrect.
Electricity costs more per BTU than oil, period. This is because electricity is, quite frequently, made from oil, gas and coal, usually at a 30-35% efficiency, never at better than 50% efficiency. Then there are the logistics issues of delivering the ultimate perishable good, invariably losing some of it on the way. All of these contribute to its cost. You WILL pay more per BTU for electricity than for any fuel.
A good, high-quality oil or gas furnace will start at 90% efficient and work up from there.
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.
Re:heating hot air.? (Score:2)
You are right, I botched on the logistics. My bad.
The cost of processing fuel is, for a large part, incorporated into the cost of electricity as well. Granted, not all power plants run on oils, some run on gas, some coal, some nukes, some renewables. Despite this, the price of finished, processed fuel has a significant impact on the price of electricity. I will make this moot in a moment.
I think we agree on radiant heat. From experience, I will tell you that a compromise solution (baseboard heat) c
Hunter Thermostat + Hacking? (Score:1, Interesting)
Insulation? (Score:3, Interesting)
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
Materials.... (Score:1, Insightful)
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 th
Re:Insulation? (Score:2)
Is that because of the cold? My understanding is stone, or rock, will hold heat far longer then wood or aluminum siding.
You don't mention what type of insulation, nor the amount, that is used in your Denmark houses.
Our house was built ~3.5 years ago in Columbus, OH, US. I believe it's built close to these:
Ceilings: R-49
Walls: R-21
Floors: R-30
Basement Walls: R-13
We have stone on the front, but siding on
Re:Insulation? (Score:2)
We put up some R19 in the ceiling hole for the time being, and the open exterior walls will get insulated as soon as I can pass an electrical inspection (re-did electrical completely - there was some
You may not need that controllability (Score:2)
it exists... (Score:1)
Controlling heating/cooling on complex schedule (Score:1)
crontab -e + d/a board (Score:1)
D/A board optional. (Score:2)
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
I know they're a dirty word, but... (Score:2)
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 w
just a though (Score:2)
oops (Score:2)
Thermostat Wiring (Score:2)
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 th
You're looking for commercial HVAC control (Score:1)
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 gre
Re:You're looking for commercial HVAC control (Score:2)
Now I suppose you could do some pretty neat things to automate a heat and hot water system, like have it learn when you usually do dishes/ laundry/take a shower and a
How long will you be in this house? (Score:2)
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 wor
A very simple solution with some safety built in (Score:2)
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, ca
An Industry Solution (Score:1)
http://www.kmc-controls.com/ [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
Re:An Industry Solution (Score:2)
Some good ideas here... (Score:2)
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.smarhom
"Most"? (Score:1)
"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...
The perfect keyboard (Score:1)
Check out thermostat & security system integra (Score:2)
occupancy sensors (Score:2)
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.
(A
How I'm going to do it (Score:1)
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
HAI Omnistat (Score:1)
I use a HAI Omnistat RC-80 computer controllable thermostat (available here [smarthome.com] for about $160, or cheaper on ebay), a serial cable (made from CAT 5 cable), and some software I wrote (available here [sourceforge.net]) 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/sunda
MOD PARENT UP (Score:2)
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!
Suggestions (Score:2)
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 somewh
not answering the question, but... (Score:2)
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.
Insulation/Heating Guidelines (Score:1)
Re:Insulation/Heating Guidelines (Score:1)
I took a class on this in Construction Management. I takes a good half hour to do a house or small business building, and you have to know the R-Values of windows, insulation (materials and thickness), etc. Check the Library, because the textbooks are pricey, and cover a lot more than you want for just this task.
Control of heating etc (Score:1)