Do programmable thermostats really save money?


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Old 09-16-14, 03:55 AM
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Do programmable thermostats really save money?

Ok, I'm sure the question has been asked before. I have a programmable thermostat. I asked a friend of ours that is a home builder. He told us they save nothing and actually cost more to use one than not use one. He says when the house cools at night from no heat, now in the morning instead of just barely running to maintain the heat, now it has to crank for hours to get it back up. If it would've ran little all night, the walls would've stayed heated, floors, etc. But now that the heater didn't run all night, everything is cold and it has to run full blast for hours to get everything heated back up. Hence, it costs way more to use a programmable thermostat than not use one.

Well, I've read other places don't let it get so cold at night. So, if we normally heat our house to 68, then if I let it go to 50, it will take forever to get warmer. So, if I set it at 60 instead at night, it wouldn't be as much heating required in the morning. But if that logic is correct.. 50 at night costs most, but 60 at night costs less overall. Then the logic would say 65 would be even cheaper, which means 67 would cost even less and 68 would be the cheapest, just proving that not using a programmable thermostat is the cheapest.

But I hear so much advertisement saying they do save money. I've heard the logic too that says furnaces run most efficient when running full blast where the quick spurts of energy to keep it up to 68 at night costs more than if you let it cool and run full efficiency for an hour or so in the morning to get it up to temp.

I guess it would be cool if I could see some real world data studies, graphs, or something that shows it really saves money.
 
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Old 09-16-14, 04:38 AM
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Hi dorlow, yes this has been discussed here and many other places, but changing old school thinking is very difficult, so going over it one more time is good.
Heat passes through your walls (everywhere) based upon the difference in temp between inside and outside. Reduce that difference and you reduce the total heat loss. So overnight a setback does save.

For most heating systems, they do run more efficiently when allowed to run longer, so the recovery process does NOT burn more fuel, it just bothers some to hear the system run that long.

There are exceptions and combinations of heating equipment where a set-back should not be used or has little benefit.

A heat pump with electric back-up can cost more if the set-back trips the emergency heat cycle.

In the floor radiant heat can take so long to recover it can be impractical to reduce the house temp even for a short while. An extreme example, but under very cold conditions the delta T to the outside can be much greater than the heating system to the inside, thus the temperature decline in 2 hours might require 6 hours to recover. Set-back then becomes impractical.

Very energy efficient homes may only drop a degree or two during the set-back, hardly worth the effort.

Deep setbacks can have an effect on interior furnishings or even cause moisture issues in areas the recover slowly, like mold in a closet or a bedroom where you keep the door closed.

Sorry for going long, but that is actually a short review of the set-back debate. Bottom line is, that builder is lost in the past and the other comments did not include any of the legitimate concerns about set-back. A typical home that cools over night will benefit from a modest set-back and that number needs to be determined by you in your home.

Bud
 
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Old 10-02-14, 06:30 PM
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This study proves that programmable stats save on gas forced air; http://www.cmhc-schl.gc.ca/odpub/pdf/63816.pdf

Gas, oil, and electric forced air units with plenty of surplus capacity are good candidates for programmable t-stats.

Heatpumps should be left at a constant temp.

Hot water radiant isn't great for major setbacks - takes too long for the water to warm back up.

Baseboard heaters are okay too.
 
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Old 10-02-14, 08:02 PM
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Programmable thermostats won't save a penny UNLESS they are programmed to fit your lifestyle. If you are like me and have a continuously varying schedule they can actually waste money. If you have a very regular daily schedule then they WILL save you money.

I have not used a programmable thermostat since I retired. I turn the heat down when I go to bed and I turn it up when I awaken IF I am cold. This last summer I was able to go weeks without turning up the heat.
 
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Old 10-03-14, 08:23 AM
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This last summer I was able to go weeks without turning up the heat.
Well, I would hope you don't have to turn up the heat in the summer! I know it's mild temps up there...but heat? In the summer?

Seriously, I've found it a lot easier to put on a robe and slippers in the morning when the temps are too cool. Within a few hours the sun has started warming the house and garage up nicely. I'm at the point now where I turn off the A/C, open the doors and windows when I get up, close them once the outside temp hits 72 or so, and it stay comfy til about 5 PM, then a bit too warm. A few hrs of A/C til the sun sets and I'm back to open windows.
 
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Old 10-03-14, 09:14 AM
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^That would never work in humid climates. Surprised that it actually cools down enough at night in az to open windows.
 
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Old 10-04-14, 01:21 AM
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Well, I would hope you don't have to turn up the heat in the summer! I know it's mild temps up there...but heat? In the summer?
Yes, heat in the summer. I cannot take the wide swings in temperature that I could when I was younger and as long as I can afford the gas bill I will heat my home when I am cold. Truth is, it will often drop below 65 degrees inside overnight during the summer months. Last year I don't think I was able to go more than three days in a row without turning up the thermostat (from night setback) during the summer.

On the other hand, I can't take temperatures much above 72 inside if I am doing anything more than watching the tube. So, yeah, I'm a wimp that wants a controlled environment between 68 and 71 degrees inside.
 
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Old 10-04-14, 01:24 AM
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Muggle, I don't know where Vic lives but I had a friend (since gone to his reward) that lived in Arizona City during the winter months. Bert told me the RH is rarely above 20% and since it is a desert it DOES get cold at night. 50 degrees at 2AM and 100 degrees at 10 AM was not unusual.
 
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Old 10-04-14, 06:48 AM
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I live in the Buffalo, NY area. We set our thermo at 76 for Summer A/C and at 68 for Winter heat and never touch them even though we have a very sophisticated thermostat. Some people say we are too warm in the summer and too cold in the winter. However, we do have perhaps the lowest heat/cool cost with any one we compare with.

It all depends on personal preference. But I might add that a little bit of self discipline can go a long way to save money. As Gunguy says using a robe and slippers in the winter will help and not expecting cold in the summer will reduce your cost big time.

In the winter we find ourselves much better acclimated to the cold because we are use to the cooler temps on an everyday basis. We find most other households and stores too warm for comfort. In the summer we try not to do lots of indoor activities and look forward to entering a home that is just a tad cooler than outside.

Overall we feel healthier than those who keep high heat in the winter and cold temps in the summer.

Our motto is "steady as she goes".

PS... we have a forced hot air gas system
 
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Old 10-04-14, 07:30 AM
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Installing that first CFL in a high use location did reduce my electric bills, but not enough to notice. Programmable stats are much the same. Yes, in some homes they will reduce the overall energy costs, but again, it may not be enough to notice, the savings lost among other variables. Beyond making sure the target home will actual save, one must select home owners willing to appreciate the incremental savings as a worthwhile effort.

Personally I enjoy savings that I know are happening whether they show up on my monthly bill or not. But in dealing with my customers, it can be counter productive to emphasis the benefits (savings) of a programmable stat when they may never see them. It is one of those asked for features you should only sell to those already interested.

Bud
 
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Old 10-04-14, 07:59 AM
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Programmable thermostats that display run time are available.

My Honeywell Prestige IAQ showed me that covering the fireplace opening decreased the run time in cool mode 2 1/2 hours from one day to the next.

Since it has an outdoor sensor it also showed me that it was hotter outside when it ran 2 1/2 hours less.
 
 

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