Power supply to heating thermostats. Commercial building.

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I have a commercial building with about five thermostats for heating. They are of the non-smart variety, maintaining the same temperature regardless of time of day, with only a pair of 24v contacts leading to them.
Given that it is a 10,000 square foot building, this is costing me a lot of money spent on unnecessary heating during nighttime.
During the day, I want the temp to be 47 degrees, and at night, I would be happy with 38 degrees or so.
Do programmable thermostats need a separate power supply, or can they run themselves from just a pair of 24v wires that they open and close?
In other words, if I buy and install programmable thermostats, will I have to run any additional wiring?
Thanks i
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On 12/31/2011 10:10 PM, Ignoramus21023 wrote:

I think if your thermostat uses power it'll require at least three conductors. Unless you can find a battery-powered thermostat?
nate
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Nate Nagel wrote:

Hi, Yes, if three leads coming into present 'stat for blower, heat, 24V AC control power lead, you can have programmable 'stat easily. Just make sure the 'stat you will get has enough wide range of temp. settings.
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I have only two leads.
i
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This is the crux of my question. Supposedly, some thermostats can charge their batteries from two 24v leads when not closing the contact, and use the battery when closing contacts.
i
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On 12/31/2011 9:10 PM, Ignoramus21023 wrote:

Most electronic thermostats have a battery compartment for two AA or AAA batteries with an option for powering the T-stat from the 24 volt supply but you usually find more than 2 conductors in a thermostat cable. Most thermostat cable has 5 wires colored white, red, green, blue and yellow. Normally red is the hot wire with blue being ground or common. A mechanical heat/cool thermostat will use all but the blue wire. A heat only thermostat will use red and white but green will used if the fan can be turned on without the heat. Unit heaters, the type you may see hanging from the ceiling in a lot of warehouses are usually controlled using only two conductor cable. A programmable thermostat can work with a two wire system if you remember to change the batteries once a year.
TDD
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If it is once a year or even once per quarter, I can live with it.
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On 12/31/2011 11:24 PM, Ignoramus21023 wrote:

The batteries will more than likely last more than a year but like battery powered smoke alarms, change the batteries with the change of season or daylight savings time change.
TDD
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On 12/31/2011 11:57 PM, The Daring Dufas wrote: [snip]

One of the few things DST is good for. Set your clocks too.
--
Mark Lloyd
http://notstupid.us
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wrote:

I rather like DST (wish it were double) but the solstice is another good time.
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On 1/1/2012 12:24 AM, Ignoramus21023 wrote:

I put a residential type Honeywell thermostat in my motor home. As there really isn't any 24 volts, AC, it runs off the internal batteries switching 12 volts DC. The batteries will last the entire summer season but may die sometime before doing the spring cleanup. Actually, sometimes they are still good in the spring. It sounds like your application is in a storage warehouse, or something similar. Is it possible to just use one thermostat at night, set to the low temp, to switch on and off the 24 volts to all the individual thermostats which are set to the higher temp? As we don't know the application and how critical the evenness of temperature is, this was just a light bulb idea.
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-snip-
-snip-
How's that going to work at 38-47F? I'm not sure if that will extend the battery life, or render it ineffective.
Jim
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On 1/1/2012 7:15 AM, Jim Elbrecht wrote:

I doubt the batteries would work at -47F but modern alkaline batteries don't seem to have a problem at 38F at all. ^_^
TDD
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On Sat, 31 Dec 2011 21:10:23 -0600, Ignoramus21023

No wiring needed. Programmable stat use batteries to power the clock but the same wires are all that is needed to make them work.
You will find that they have a minimum setting of 40 degrees. Yeah, 33 would save fuel, but 40 give a safety factor in case the heater break down.
I've had good experience with Honeywell and White-Rodgers. We have a couple dozen or so in our building.
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And those, are two wire programmable thermostats with a battery? Right?
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On Jan 1, 12:24am, Ignoramus21023 <ignoramus21...@NOSPAM. 21023.invalid> wrote:

Take a look at any of the programmable thermostats at HD or online. Everyone that I've seen runs off batteries and will work with a simple two wire connection. Some will also use 24V, if available. Some also have an internal failsafe switch that will close at around 40 or so in case the batteries are dead. I'd check the min temp before you buy one. The ones I've had for sure will not go down into the 30's. Think 45 might be the lower limit.
And before going below 45, I'd consider where pipes that could freeze are located. For example if they are in outside walls, it's going to be substantially colder there than where the thermostat is located. When I've set back real low, like below 50, I make sure to leave open the cabinet doors under sinks that are on outside walls too so that it can get some more warm air in there.
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On 1/1/2012 8:09 AM, snipped-for-privacy@optonline.net wrote:

(snipped)
I do believe you are correct about the 45 degree F lower limit. I looked all over a couple of years back to find one that would go down into the high 30's with no success....45 was the lowest I could find.
Don
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On 1/1/2012 6:50 PM, IGot2P wrote:

I have a Honeywell TB8220U1003 Commercial VisionPRO 8000 Touchscreen Programmable Thermostat sitting here on the desk. It goes down to 40F in heat mode. I found it laying around in an electrical room where all the separate thermostats had been removed to implement a remote controlled energy management system. I put 3 AAA batteries in it so I can use it as a thermometer and clock and the 3 1/2" X 2 5/8" LCD screen back lights when I touch it. Just for giggles I looked it up and found that it lists $439.29. Darn, this thing will do all sorts of stuff. o_O
http://customer.honeywell.com/honeywell/ProductInfo.aspx/TB8220U1003
http://preview.tinyurl.com/7hhf2bj
TDD
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Look at Honeywell. I checked a half dozen models and the specs are 40 degrees.
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On Dec 31 2011, 10:10pm, Ignoramus21023 <ignoramus21...@NOSPAM. 21023.invalid> wrote:

If you think it is costing you a lot of money on unnecessary heating just wait until you have a pipe burst when you try to save money by turning the heat down lower...
A setback to 38 degrees is too close to freezing considering that it might be colder further away from the thermostat location...
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