Cooling season and progammable thermostats

[Michael Cunningham]

Folks,

I turned on the AC for the first time last night when going to bed. I have a programmable thermostat that I can set up a schedual on with target temperatures. I used a schedual all winter long for heating ranging from 70 during the evening to 63 the rest of the time. I didnt really notice a savings however.

Basically.. my question is that if I setup the thermostat to cool the house to 70 in the evening/night and let it get up to 80 during the day am I really saving money over just letting it be set at 70 deg 24/7?

Doesnt the system have to exert a lot of energy to get the house down from 80 to 70 every evening when the timer kicks off?

Is it more or less energy then would be exerted just to keep it at 70 all the time?

Do programmable thermostats really save you money?

Thanks, Mike

[Doug Kanter]

Try 75. You might be surprised at how comfortable that can be, especially at night when your body temp goes down anyway.

Yes. I've been told repeatedly not to set up a wide margin of difference.

Your electric company can probably help you calculate this quite accurately. Call them.

Yes.

[Joseph Meehan]

They will, almost always, save you money. How much depends on a lot of factors.

Often too wide a range may not save any more than a little less of a range. Exactly how to program for the greatest savings, is more of an art than a science.

I suggest you program yours based on your comfort. Program the warmest possible temp that you are comfortable with.

Mine has a feature that records the total operation time. That along with cooling degree days for your area provided by the weather people and some testing can help you see how much you are saving.

Good Luck

[Doug Kanter]

Nice feature. What brand?

[Doug Kanter]

By the way, AC lowers the humidity in your home, which is often MORE of a factor than the temp, in terms of being comfortable. That's another reason why shooting for 70 degrees may be totally unnecessary, unless you're having a house full of people over for a party and you want to get ahead of the warming created by having lots of bodies and cooking.

[Joseph Meehan]

Hunter

-- Joseph E. Meehan

26 + 6 = 1 It's Irish Math

[David Efflandt]

It really depends upon the home and type of heat, and whether you are comparing fuel use vs. degree days, or just did not notice lower bills due to rising fuel prices.

There should be no reason to set an air conditioner at 70 unless the weather is mild and just trying to remove humitity. 75-78 degrees F. should feel perfectly comfortable as outside temperatures rise, unless your system is oversized and cycles off so quickly that it fails to remove humidity. If you want to save money, get your body used to seasonal temperatures.

But I live in an old home with steam heat, so I only use setback during spring/fall mild weather to eliminate boiler run cycles during the day when I get solor gain and at night (heated waterbed). In coldest weather I set it at 66 and leave it there. In warmer weather I vent air in or out at night with an upstairs window fan and close everything up during the day with blinds adjusted to reflect the sun. My window and wall shakers usually only get exersized on warm summer evenings or hot weekends. Dropping the water bed thermostat down slightly makes it a great heat sink to keep me comfortable at night.

[Jacques]

You guys seem pretty familiar with A/C thermostats - do any of you know where I can get one with THESE specs: "Wall-mount programmable thermostat, double-pole, line-voltage for a 220-v wall-mount A/C unit". Would prefer 7-day programming, but 5+2-days would be fine. Thanks very much.

[frytech]

Such a device does not exist. I could be cobbled together with a 240 primary / 24 secondary transformer and a 2 pole contactor.

The arcing of 240 volts inside a programmable thermostat would soon scramble the electronics in the thermostat, not to mention the relay would have to be pretty heavy duty, plus the thermostat would have to be huge to accomodate a built in transformer, heavy duty relay, circuit board ect.

[Jacques]

Thanks NOPE - I guess that puts me back to Square One. Would you mind letting me know what "arrangement" IS possible AND safe? (One suggestion that suppliers have made: "You should put in a transformer and relay, and convert from 220v to low-voltage. That way you'll be able to use a low-voltage programmable thermostat". Is this workable? Thanks again - much appreciated.

[SQLit]

Why are you attempting to control from the line side?

[frytech]

A contactor and relay are basically the same thing, except a contactor is more heavy duty than a relay.

It's a simple job but without drawing a wiring diagram it's difficult to give step-by-step instructons and if you are not familiar with electricity and the terminology involved you could either curl your hair or kill you or release the factory smoke from several components and aa good programmable t-stat costs from $75 to $150

the contactor is a heavy-duty electrically operated switch, turns on or off the A/C, it's powered by the 24 volt output of the transformer, and controlled by the output of the t-stat. The t-stat gets it's operating power from the same 24 volt output from the transformer.

[frytech]

Not I. OP was asking for a DPDT programmable Line Voltage t-stat.

[Jacques]

Thanks again NOPE: I've been talking with Aube Technologies

They've recommeded (what they consider to be) a very simple strategy:

1. install the Aube electromechanical relay (with built-in transformer - either directly within the AC Unit, or directly connected to the Panel; and
2. install their new Heat/AC programmable thermostat TH141-HC-28 This approach apparently gives me additional flexibility, as well (ie: I can replace the existing line-voltage baseboard-heater thermostat (which I was going to do anyhow) with this Aube therm - and install a second Relay to and connected right onto the two series-connected baseboard heaters: One thermostat, dual function. (Plus: That eliminates ANY possibility of popping a breaker: The A/C unit and the heaters can NEVER be on at the same time).

Does this all make perfect electrical sense???

[frytech]

It does make electrical sense. I admit I have not heard of Aubtech , Interesting product line they have. They are probably proud ($$$) of those relay circuits. There are advantages to it being able to fit in a 4 x 4 box, but if any one part fails it all fails.

[m Ransley]

Maybe 1-9 % but over 20 yrs its alot., enough to buy a car or boat

[Jacques]

Thanks to all who took the time to make thoughtful comment. Here's where I've ended up, based on advice of a well respected supplier:

. Install a Relay With Built-In Transformer made by Aube Technologies Model Number

840T.

. This Relay will be installed directly inside the AC Unit.

. Will also install a new Programmable Heating/Cooling Thermostat by Aube

Model Number TH-141-HC-28.

. This thermostat is NOT powered by low-voltage, but by two AA batteries.

. Will use #18 or #20 wire for connection between the Thermostat and the AC Unit (44 feet)

. Will use use #14-2 or #12-2 wire for connection between the AC Unit and the electrical Panel (16 feet)

. Operations: AC Unit will operate as before/as normal. Manual dials on the AC Unit will all be functional as before/normal (ie: temperature-level setting ... blower-fan settings) - with one possible/probable exception: May not be able to run "fan only" ... may be that fan will only function if/when compressor operates at the same time.

. Sounds good to me. I expect that means I'm missing something.