locking my thermostat

pgamblin

My wife and kids are killing me with w/electric bills. I come home at 7:00 or 8:00 pm and find the thermostat set @ 70 deg. It's hot here in·Houston and my house won't see 70 deg until·the end of October·With daytime temps in the mid 90's, this means that the AC never shuts off. I have begged and pleaded but to no avail.·I need some idea as to how to determine which two wires to put put my relay contacts into. Since I can pretty well plan on some ridiculous setting that will have the unit in question running @100%, I'm planning on setting an arbitrary 33% duty cycle via my relay·contact(s).· The wires inquestion are red,green,blue yellow. Simply a single heater and single AC. My thought on the AC is to look at the wiring at the contactor for the compressor. I'm kinda lost on the heater. I am using a honeywell programmable thermostat and am really surprised at terminals are labelled by color and not function.
thanks.

Franklin

Check the honeywell site for schematics. Or try this www.ventingdirect.com/index.cfm/page/product:display/productId/TG511A1000/manufacturer/Honeywell/finish/Clear%20Acrylic&source=googlebase?CAWELAID=194726318

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- Stephen

fiveslo

Cheap and easy would be as Franklin suggested... locking cover for the thermostat...
however if you want to know how the thermostat should be wired·then here are
the "typical" colors for what they do... Double check that the wires are really
connected this way since, every Tom, Dick and Harry seem to have their own
special way of hooking up thermostats to the HVAC equipment... this is the way it
should be hooked up, not meaning that yours is·wired in the same "color" fashion...

pgamblin

Thanks guys for the ideas and wiring colors. I'm thinking a solid state solution would be less "confrontational". I'm getting closer to not caring.

pgamblin

I did manage to find a manual. I have a 4 wire White Yellow Green Red termination. The Rc Rh terminal is jumpered and terminated to a
red wire. Extrapolating from fiveslo's list and considering I only have single stage heating and cooling, looks like Yellow must be cooling and
White heating. I think two relay contacts should do it. Now I just need to line power it.

Franklin

Most thermostats are 24V so I'm not sure what you mean by 'line power' I would use the wires before they get to the controller and stay on the low voltage side. Most US furnaces/Heat Pumps/ Air Conditioners are 220VAC remember.

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- Stephen

erco

Alternative solution: instead of modifying the thermostat, which could be obvious and confrontational as you call it, modify your air handler/condenser (same thing, different names). You must have a drip pan under your condenser (way up in the attic, out of sight, out of mind, away from your family) to drain off condensation through a gravity drip line. There's a water level sensor switch in this pan that provides a simple on/off signal to your compressor. If too much water accumulates (due to a blockage) in the pan, the switch trips and turns off the compressor, no matter what the thermostat is saying, before the condensation overflows and wrecks your ceiling. You could add a set of relay contacts in line with this water level sensor to trip at some adjustable duty cycle.

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·"If you build it, they will come."

sam_sam_sam

pgamblin

There is something else that· might work as well· Honeywell has on there higher end thermostats that has a way of setting the· min set point for temp in cool and heat it in the tech setup menu also there is a locking feature that allow you to lock the thermostat it will only let you turn it on and off

I·found the thermostat link here it is

http://yourhome.honeywell.com/Consumer/Cultures/en-US/Products/Thermostats/Programmable/Do-It-Yourself/7-Day/Touchscreen/Default.htm

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··Thanks for any··that you may have and all of your time finding them

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Sam

Post Edited (sam_sam_sam) : 8/19/2008 1:02:33 PM GMT

RDL2004

Why not just use one of these? Much cheaper and easier (but definitely not as much fun or as interesting).

www.prothermostats.com/category.php/thermostat-guards/?category=290

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- Rick

pgamblin

By line powering, I meant powering up my project. I'd rather not use batteries for Stamp power. Erco thanks. That is the the angle for me. I can get power from an attic outlet for the stamp. I paid for an overflow cut off, but I don't remember seeing it. That is an excellent entry point for me. Simple enough. It is rather gratifying to build a project that will save $ instead of simply burning it.

erco

While you're·crawling around up in the attic, consider adding a thermostatic circuit to control your relay contacts on your overflow switch. Your initial·post was·to have a Stamp controlling some arbitrary duty cycle is an open-loop control system, your house will be hotter on hot days and cooler on cool days. If you drill a tiny hole in your ceiling in an inconspicuous area and drop a thermistor (or higher-tech temp sensor) down into your living space, you can use a Stamp or an even simpler circuit (such as http://home.chattanooga.net/~cdp/fridgctr/fridgctr.htm) to give you a closed-loop solution that will be your secret thermostat. And naturally, you'll figure out an inconspicuous switch for you to bypass the secret thermostat when you decide you need some extra cooling.

I guess you're fairly certain your wife & kids aren't closet Parallax fans reading these posts. What's our silence worth?

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·"If you build it, they will come."

Chris Savage

My solution when I lived in NY was to build my own Digital Thermostat. I was really the only one who knew how to use it, so I had more inherent control over temperature.

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Chris Savage
Parallax Engineering

CannibalRobotics

Get another thermostat and put it somewhere else.
Unhook the one everyone is messing with and that's the end of the discussion.

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A wise man told me; "All electronics are made to work by magic smoke.

Don't ever let it out as it's·very difficult·to get it back in."

GICU812

Or, do like I do, just turn off the breaker for the AC compressor! The fan still runs, air still moves, so the GF "thinks" the AC is on, and that is enough to make her think it is cooler. That and the circulating air does help.

Instead of snagging power, why not just use a bridge rectifyer and get 24vDC from the thermostat line, then transform that down. Would save space and wiring.

When I get around to my home automation system (im in phase one with the security now) I am incorporating the thermostat into it, and I will be programming in some "fudge" room with the heating \ cooling, in relation to the outside tempature that will determine whether the fan runs, or the AC runs, as well as a "wandering" tempature, that will slowly raise the desired temp back to what it should be. Im also putting in some neat ideas, like "chill" where it just runs the AC for like 5 minutes to take the humidity down, or cool the room before I go to bed. Id like to incorporate some servos and put them on the dampers so I can control airflow, but thats probably too far out there.

sam_sam_sam

GICU812
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Instead of snagging power, why not just use a bridge rectifier and get 24vDC from the thermostat line, then transform that down. Would save space and wiring.

You can ONLY do this if your thermostat·has R and C

If the C is not there then you will have use one more wire that on the other side of that Transformer

I had a Project that I just finish about month ago where I did the same thing· But I used a Switching Power Supply to power the Basic Stamp and the
LCD Display·that Parallax sells

Here is the link to that Project

http://forums.parallax.com/showthread.php?p=737892

June 2008 Nuts & Volts has a Switching Power Supply Rated @ 3 Amps Project and they sell it as a kit

The kit is very easy to put together

When I get around to my home automation system· I am incorporating the thermostat into it, and I will be programming in some "fudge" room with the heating \ cooling, in relation to the outside tempature that will determine whether the fan runs, or the AC runs, Which FAN



As well as a "wandering" tempature, that will slowly raise the desired temp back to what it should be.This only happen when you are getting WARM AIR from behind the thermostat where the wire go to it or if you go in and out of you house alot




·Im also putting in some neat ideas, like "chill" where it just runs the AC for like 5 minutes to take the humidity down, or cool the room before I go to bed. This can be done by switching to a slower fan speed Just watch you Suction Line Temp when doing this

·Id like to incorporate some servos and put them on the dampers so I can control airflow, but thats probably too far out there.
This could be done but LIMTED how many DAMPERS to TWO if you are going to want FULL Control Dampers meaning that if you want·CLOSE that Damper all the way

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··Thanks for any··that you may have and all of your time finding them

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Sam

Post Edited (sam_sam_sam) : 8/23/2008 9:36:41 PM GMT

GICU812

Well, unless your thermostat is battery operated, its got to be getting power you can snag. I guess there are battery operated ones that just switch the line for signaling though. Actually, if you dont have a battery thermostat, it is probably allready recifying and regulating the voltage. If you have spare wires in the thermostat wiring, and watch your amp draw, you could proabably tap the regulator in the thermostat and ship the power back to your stamp. You'd want to be very careful not to miswire it though!

The furnace fan is what I meant, I would just activate this while the display would show that the AC was running. From my experiences, within a reasonable range, air conditioning is more psycological than thermal. For a couple of weeks in the spring I left the breaker off, but still nagged tue GF about running the AC all the time. But she HAD to, because it was so hot, so she'd turn it on and everything would be fine, even though the AC wasnt actually running, lol. Now I've got her trained to use the fan first, AC second. But I never did tell her about that, because I still use it sometimes. My house is a split level, so the familyroom is 4' underground, it stays very cool there, and the middle level with kitchen is on a slab, so that feels cool.

I think you misunderstood what I meant by wandering tempature, as in, if someone changes it from what I want, it slowly adjusts the set tempature back to my setting. So if I have it set at 78 and someone changes it to 75, it will go back up one degree every 10 minutes, so if they check it again, they think I just changed it back, but the jump isnt so sudden that they dont get enough cool out of it to make them forget.

As for chilling, Id rather just have the AC kick on for 5 minutes then shot off than modify anything. Just a couple of minutes in my house does wonders, mostly the humidity I think.

As for damper controlling, I have all round duct dampers, so they spin, 90 shuts them, another 90 opens. I have access to every damper, so I was thinking of just mounting solenoids on the damper arms. Though in reality there are probably cheaper more efficient ways of doing this, like opposing solenoids, one pulls shut the other pulls open.

sam_sam_sam

GICU812

I think you misunderstood what I meant by wandering temperature, as in, if someone changes it from what I want, it slowly adjusts the set temperature back to my setting. So if I have it set at 78 and someone changes it to 75, it will go back up one degree every 10 minutes, so if they check it again, they think I just changed it back, but the jump isn't so sudden that they don't get enough cool out of it to make them forget



Thank You For explaining that·to me about what you meant

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··Thanks for any··that you may have and all of your time finding them

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Sam

allanlane5

Just a thought -- at work they put vented plexiglass boxes around the thermostats, screwed solidly to the wall. This way you can SEE the thermostat, but not change its settings.