Programmable versus Smart Thermostats

What's in a name?

Thermostats for home heating control are older than you may suspect. No, archeologists did not see the Honeywell Round in the prehistoric cave paintings discovered in Font Du Gaume in France. They are, however, the only polychrome cave paintings you can still visit.

No, the first thermostat was invented in 1830 in Scotland. Not very practical in its day, innovations continued until the first useful thermostats began showing up in the late 1800s. The mechanism was simple; a bi-metal coil moved a mercury switch. At a certain point, the mercury completed an electrical circuit, and the furnace was turned on. The warm air caused the switch to go back to its original position, breaking the connection and turning the furnace off. It's science, ya'll.

An early leader in consumer thermostats

Honeywell captured a large share of the manual thermostat marketplace with their classic Honeywell Round design. It's likely you have seen one or lived somewhere that had one. Cool mid-century modern design and rugged, reliable design made it a best seller. Even today, you can get a 21st Century edition, non-programmable of course.

Programmable thermostats take the spotlight

Long before conserving energy came into vogue, programmable thermostats hit the store shelves. Convenience was the mother of this invention. Since thermostats were centrally located, they were rarely right outside the bedrooms. It was easy to set the temperature back on the way to bed for cool sleeping bliss. However, crawling out of your toasty bed to turn the heat up in a chilled house wasn't popular with the masses.

Programmable thermostats allow you to set temperature levels and start/stop times. Once set, the program operates your furnace according to your schedule. A top-of-the-line programmable thermostat will allow you to set up the following schedule:

• Four discrete daily time settings - Wake, Leave, Return, Sleep.
• Temperature settings for each of the above.
• The ability to create different programs for every day of the week.
• A "Vacation" or "Away" setting.
• Heating and cooling modes - each with all the features mentioned above.

You can still buy these thermostats and they work extremely well. However, I found the programming options to be tedious and restricting. Someone was always tinkering with the schedule, the temperatures and generally messing things up.

Enter the smart thermostat

I clearly recall when Nest announced its Smart Thermostat. I was instantly captivated and purchased one of the first generations. I loved everything about the product. Former Apple employees started Nest and that influence was evident in the design, the instructions and the packaging.

The Nest looked like a giant jewel in its cleverly constructed packaging. About 30 minutes later, I had the Nest connected to my wifi network and controlling my furnace. That very same thermostat is on the wall of my current home a decade and a half later.

Set and forget - the smart differentiator

What really caught my attention was the Nest claim that it would monitor the family's activities and construct a schedule around our preferences. I just set it up, entered a maximum and minimum temperature and let it do its thing. Did it work, it did indeed.

Today, I can connect to and control my Nest via my smartphone. Let's say I am away on holiday in the South of France. I hear of a devastating ice storm in Minneapolis. Worried that I have no power and stuff will burst, I check the temps right from my phone. Ah, sweet relief. Now, where was I?

Which type is right for you?

The smart option

If you are a gadget person enthralled with the smart house concept and being able to manage your home via your phone, go for the smart thermostat. It's a no-brainer in my opinion.

Here are the features you should look for in your smart stat:

• Supports self-installation;i.e, a DIYer can install and set it up.
• Learns your patterns so you can set two temperatures and let the computer do the rest.
• Provides a geo-fencing capability...more below.
• Satisfies your visual aesthetic.
• Works with Alexa and other smart home assistants.

Okay, I sprung geo-fencing on you. That feature ties the thermostat to your phone or anyone else you choose in your household. You set a perimeter around your home, say one mile in diameter. Once your phone leaves that perimeter, the thermostat puts itself in Away mode. When you cross back over that perimeter on the way home, the thermostat turns the HVAC equipment on. If you set your perimeter just right, you can arrive home to a properly conditioned living space.

The programmable alternative

These thermostats are generally less expensive than a smart alternative. No surprise there. If you are on a budget and setting a detailed schedule works for you, programmable stats are a good solution.

In terms of the features to look for in your programmable thermostat, I refer you back to my earlier list. You can buy versions that allow you to group days of the week. Here's what that means.

• A thermostat with a 7-Day capability is the one I described earlier. Individual schedules can be set for each day of the week.
• One with a 5-2 Day capability lets you create one program for the work week and another for the weekend.
• Finally, a 5-1-1 Day capability is the same as the 5-2, only you can set a different program for Saturday and Sunday.

That's all the permutations available, so don't ask for a 4-3, 6-1 or some other combination.

What thermostat do I recommend?

In the spirit of full disclosure, I was a product manager for Honeywell in their Commercial Controls Division. So, when you see my recommendations for Honeywell thermostats keep in mind it isn't because I am biased it's because I happen to think they are the best thermostat on the market - for the programmable choice.

Programmable

Honeywell Wi-Fi 7-Day Programmable Smart Thermostat with Digital Backlit Display

Traditional 7-Day programming capabilities with a clean interface and easy installation. It brings these thermostats close to a "smart" model with several features like app control and wifi connection. At $70, it's affordable and available from Home Depot.

​​Want a bare-bones option? Consider the Honeywell 5-2 Day Programmable Thermostat with Digital Backlit Display.  
Only two schedules to enter and easy button navigation can be yours for around $30, also from Home Depot.

Smart learning

Nest Learning Thermostat - Smart WiFi Thermostat - Stainless Steel
This is the nearest version to what I have used for years. The feature list has continued to grow, adding more smarts to monitor weather conditions and adapt your temperature settings to compensate for them. It is the first Energy Star certified learning thermostat.  
The thermostat has a proximity/motion sensor that lights up the dial when it senses someone nearby, displaying current inside temperature and other information. It is well worth the $250 price tag Home Depot puts on it.

Why not a Honeywell smart learning stat?

I had a first-generation Honeywell Lyric for many years. In fact, I swapped out my Nest for the Lyric to get the geo-fencing feature. And it worked beautifully. Recently, it simply died after a power outage. When I went to buy a replacement, I was greeted with a roadblock - the Lyric was only available through a Honeywell distributor who had to install it.
This is a DIY blog, right? I had installed the Lyric in three locations without the least bit of trouble. I had no doubts that I could install the replacement. However, the evolved business model dictated that I had to pay to have it installed. No thanks. A lot of other Honeywell products fall into this category. Since my Nest was at hand, I put it back in service and it caught right up. Oh, and it now has a geofencing feature. Sweet.

Compatibility with utility energy programs

One last thing to consider is buying a thermostat that can be part of your utility's energy or load control program if they have one. My utility has a summer peak load control program. On especially hot days when demand is at its peak, the utility can send a signal to my thermostat and adjust my cooling temperature to reduce demand.

Before gasping in horror about letting a faceless entity monkey with your comfort, let me give you more details. The temperature changes a modest, 2 - 3 degrees is common. And, the control is cyclical. A lot of math has gone into the design so that your home doesn't become noticeably hotter. If they control too long, your home gets hot and your AC works harder to catch up. In other words, it defeats the purpose of the program.

In my case, the utility had a BYOT (Bring Your Own Thermostat) program. In exchange for a few bucks off my bill each year, I let them control my temperature setting on peak demand days. If I want to, I can drop out and the only downside is I don't get my bill credit.

Other utilities may provide you with a shiny new thermostat and have it installed for you. These programs are a bit more stringent. If you drop out, you might be on the hook for the cost of the stat and installation, or a pro-rated share of the cost.

A third option is when your utility gives you a rebate if you purchase an approved thermostat and enroll in their program. Be cautious here. A popular thermostat with utilities is made by Ecobee. It is a fine product but is not DIY friendly. I purchased one to test in my former utility offices and had to have one of our electricians wire it up. That was a first for me.

Installation overview

For the most part, all thermostats you buy today are connected to the HVAC system using colored low voltage (24 volts) wires that look like old telephone wiring.

Check the picture below of an old mounting plate I had in my spares drawer. You will see the terminals are marked with letters and an occasional number.

Here is the meaning of the labels. They are surprisingly logical - to a point.

• Rh - Red wire for heating - power
• Rc - Red wire for cooling - power
• Y1 - Yellow - signaling to the cooling equipment
• G - Green - the blower/fan
• W1 - White - signaling to the heating equipment
• O and B - Switches changeover valve in heat pump systems
• C- Common - part of the power circuit

Note: There are other possible label variations like Y or Y2. Just match them to the same terminals on your new mounting plate.

Prevent an unpleasant experience

There are two things that you must do to ensure a trouble-free installation:

1. Label your wires before removing them from the thermostat mounting plate. Some thermostats come with little wiring tags which are cool. In the 21st Century, taking a picture with your smartphone serves the same purpose/ Gogin the Luddite route means making a sketch or list of what color wire goes to which terminal.
2. Do not let your wires slip back inside the wall!! Unless you are good at fishing wires from inside walls, you'll be calling an expert to fix the issue. Tape them together with masking tape, wrap them around a pencil or tape them to the wall. Whatever you do, be sure you don't lose them!

Tools you'll need

• Phillips screwdrivers - normal size for handling wall screws and small for wiring terminals.
  Note: My Nest thermostat came with a nifty screwdriver for use connecting wires to the terminals. This is especially useful to those without these small, electronics-oriented tools.
• Bubble level
  Note: Both the Lyric and Nest had a built-in bubble level. In the past, a level was needed to position the mercury switch properly. Today, it is for aesthetics.
• Masking tape - for wire retention
• Wire cutters - trim the existing wires if damaged.
• Knife - remove wiring insulation.
• Drill and bit large enough to accept a wall anchor - you may be able to use the existing mounting points. Otherwise, you'll need to drill at least one, and maybe two new holes.
• Wall anchors and screws - in case the new thermostat didn't come with them.
• Hammer
• Touchup wall paint and brush - most folks paint around the thermostat mounting plate when refinishing a wall. If your new thermostat leaves some of the old paint exposed, you should touch it up.

Step-by-step

1. Turn off the HVAC system - throwing the breaker is the best approach. You do not want the system trying to run while you are working on it.
2. Pop the old thermostat off the mounting plate. Most snap right off or are pulled straight out. Play around carefully so you don't break anything or pull the mounting plate off the wall.
3. Record wire positions as described above.
4. Secure wires as described above and remove the mounting plate.
5. Read the installation instructions for the new thermostat. A lot of companies today provide videos or installation animations in the app.
6. Install the mounting plate.
7. Drill new holes using the mounting plate as a guide or a template, if one was provided. Make sure the plate is level.
   Tip: I make a point of trying to reuse at least one of the existing anchor points but that isn't always possible.
8. Install the wall anchors if needed and install the wiring plate.
   Note: Some thermostats come with different 'decorative" backplates. These allow you to hide the paint mismatch if the size difference reveals any. I used one provided with my Nest. Follow the instructions for installing it at the proper time.
9. Reattach the wires according to your reference sketch and any changes required in the installation manual.
10. Snap the new thermostat into the plate and get ready for energy-saving fun!

Final thoughts

Before buying any thermostat, you need to know what you are controlling. Heat pumps require specific thermostats to control them correctly. You need to know if you have single or two-stage heating. Do you have multiple zones? You'll need more than one thermostat. If you have baseboard electric heat, no joy for you, at least not yet. Do you heat with a boiler? Steam? You don't have to be an HVAC master but knowing what you need to control means getting the right thermostat on the first try.

How much can you realistically expect to save?

Drumroll please...survey says, "Up to 10%, depending upon settings, weather and other variables." I'd guess I save around 5% but it is a difficult number the calculate. Even so, every saving, no matter how small, can have an enormous impact when millions of people are all saving that amount. Conservation is a marvelous and effective way to live a lower carbon lifestyle.