New Technology

I've been eyeing the Nest thermostat for a while -- it's a "learning thermostat" that figures out daily patterns and doesn't need to be reminded after a while.  My old thermostat has a couple minor problems -- can't see the display in the dark, the access door is broken and keeps falling off, and since I've been retired I have often turned the heat to "bypass" the automatic program (which was designed for when we were both working all day) and then forgotten to turn it to setback when we go to bed.

And hell I have the money now.

It connects to the Internet via wi-fi, and automatically configures itself for date and time.  It downloads the current weather and displays it.  (Supposedly uses this somehow to control the furnace, but I'm not sure how).  It has a proximity sensor, so it's dark until you get within 5 feet of it, then it lights up with a nice bright temperature reading (white for current temp, turns blue if you lower the setting, orange if you raise it).  To adjust the temp you simply grasp the ring on the outside and rotate clockwise or counterclockwise -- very intuitive.

As it is network connected, it downloads its own software updates as needed.  After you've had it a while you can get printouts of past performance.  You can log into it with your smartphone (though I haven't figured out how to change the temp prior to coming home).

It's quite a nice unit.  Designed by former Apple engineers I understand.

The software app that you can download for it has, as one of its adjuncts, a list of other gizmos that work with it.  One is called SkyBell -- a Bluetooth enabled doorbell.  When someone pushes the button, it turns on a microphone and camera, so you can see and talk to whoever is there.  Over your phone or computer.  From anywhere.  Neat idea (though not sure why I'd need it).

Ah okay, my thermostat is somewhat limited by my furnace, which is a very basic three-wire arrangement.  I can turn on the heat, I can turn on the fan to circulate air.  My HVAC does not provide cooling or whatever other functions are provided by the eight other wire possibilities.

So, on my iPhone screen I have two settings: "Home" and "Away."

If I press Home the house heats up to the normal temperature for that day and time. Pressing Away causes it to drift down to the setback temperature.

The temp limits of this thing are 50 degrees to 90 degrees.  Yikes.

This is kinda cool -- you can configure what the unit lights up with when you walk by: temperature, analog clock, digital clock, a couple other things. I set it to analog clock -- a very subtle clockface, no numbers, just slim white hour and minutes hands and a slim blue second hand.

Elegant.

When I walk down the hall, I have to raise my arm and touch a button to get the thermostat light to come on and show me the time and temp. I have to lift my arm! I might as well be living in a cave.  

Suffering catfish.

That's succotash. "sufferin succotash!"

Very clever, the programming on this thing.

Before the first week was out it figured out my daily routine and populated the rest of the work days with the schedule I had established: up at about 8:15 am, to bed about 9:30 or ten.

Trouble is, Mrs. NoCo was out of town last week.  She's back now, so will want the heat to come on at six and will go to bed about 7:30 pm.

One of the menu options, as you turn the outer ring, is "Schedule."  Selecting that brings up a graphical representation of the week, with your programmed thermostat settings superimposed. To change a scheduled setting you just move the cursor to that setting and press "change."  First it allows you to change the hour, and then the temperature. Very slick. In about one minute I had reprogrammed the week.

This thing was very expensive, and doesn't do anything a $40 thermostat won't do. But it does it so elegantly and intuitively that I'm still impressed.

And I don't impress easily.

Can it control zones?

In a word, no.

The instructions indicate you can buy multiple Nests for multiple zones, and they all are aware of each other and can be controlled by the Nest app, but each one does only a single zone. Which is fine with me, I have central forced air.

Other new technology in the house (I left the thread title open, because the thermostat was only one of my projected purchases): a new reading lamp.

I have two main reading locations, upstairs in the living room and down here in my music room.  A couple years ago I bought a very nice articulated LED reading lamp for upstairs, to replace the series of "full-spectrum" fluorescents which were too fragile to live.  The LED provides almost the same spectrum, but it doesn't get hot and it isn't fragile.  The arm on this lamp is super long, allowing you to place the base a foot away and still position the lamp head directly above your book.  The head on it is closed, with no light leakage (unlike many designs, unaccountably) so the light goes on your book and not in your eyes.  As I have gotten older I need fairly bright light to read comfortably.

So I went shopping this week to try to find another lamp like the one above (literally and figuratively).  No dice.  Of course anything I like has to be discontinued.

But I found an alternative.  It's an LED bar lamp, with two articulated joints (so you can adjust the height and angle) PLUS something I'd never seen before: the light bar rotates.  This way you can aim it away from you just enough that it doesn't shine in your eyes (the LEDs are recessed just a skosh).  Plus it has four brightness settings.

The next model up had a really neat continuous dimmer on a ribbon controller -- but it was freaking $350!

NoCoPilot wrote:

In a word, no.

Well that sucks. Can it use a remote sensor?

I don't think so. Everything indicates it has to be in the room being controlled.

Listen, it's a high-end geek gadget, not a commercial warehouse thermostat.

There are a lot of multi-level homes with zoned HVAC, There's that nasty old physics problem of cooler air hanging about downstairs while the warmer air stays upstairs.

Remote sensors are found in many homes, because the most convenient place for the thermostat is seldom the best place for measuring the temperature.

I looked on the Nest web site and it appears that it is compatible with zoned systems. Sometimes.

Quote :

A multistage system will have multiple heating wires (such as W2 or W3) or cooling wires (Y2 or Y3). The Nest Thermostat is compatible with up to three stage conventional heating (systems with W1, W2, & W3) and two stage conventional cooling (systems with Y1 or Y2).

Ah, that begins to explain the multitudinous wiring options inside this thing.  I wondered what that was all about...

_Howard wrote:

Remote sensors are found in many homes, because the most convenient place for the thermostat is seldom the best place for measuring the temperature.

I can believe this -- but I'm having a hard time explaining to myself 1) why you'd need one multi-zone thermostat to control multiple zones instead of using multiple single-zone thermostats, and 2) when you would ever place a thermostat in a location where the ambient temperature wasn't what you would want measured.

I guess #1 could be explained if using central air and a system of baffles or dampers to control where the warm air flows.  #2 is still a mystery to me.

Quote :

When multiple thermostats control one system, the house is divided into zones using dampers in the ductwork throughout the house. When one zone needs heating, the damper for the ductwork in that zone opens, guiding the hot air to that zone.

We just close the vent in the guest bedroom. Manually.

NoCoPilot wrote:

...why you'd need one multi-zone thermostat to control multiple zones instead of using multiple single-zone thermostats,

It's not a matter of need, so much as matter of preference. An option which the thermostat could provide.

NoCoPilot wrote:

...when you would ever place a thermostat in a location where the ambient temperature wasn't what you would want measured.

In most homes, the thermostat is put where it is convenient. Most homes have them in a hallway, which is almost always the worst place to put it. That is why it is best to place a remote heat sensor in the proper place and the control in the convenient place.

NoCoPilot wrote:

Quote :

When multiple thermostats control one system, the house is divided into zones using dampers in the ductwork throughout the house. When one zone needs heating, the damper for the ductwork in that zone opens, guiding the hot air to that zone.

We just close the vent in the guest bedroom.  Manually.

There's more to it than is contained in that quote. Dampers are opened and closed to direct the heating or cooling to one or more zones. But there are some catches.
If you have a small zone, then you need a furnace that has multiple levels in the fire box. Older. and cheaper, furnaces do not  have this feature and so cannot be used for small-volume zones. An A/C compressor which can run at a low level is also best, although I'm not positive that it is required.
Never close the vent in your bedroom - or anywhere else. The system, if properly designed, needs all of the vents to be open so as not to create back pressure in the system, which can actually lower the air volume in all the vents that are still open and drastically reduce the efficiency of the furnace or A/C. In a zoned system, when some of the vents are closed, a dumping damper will be opened to keep from creating back pressure.

_Howard wrote:

Never close the vent in your bedroom - or anywhere else. The system, if properly designed, needs all of the vents to be open so as not to create back pressure in the system, which can actually lower the air volume in all the vents that are still open and drastically reduce the efficiency of the furnace or A/C.

Never heard this before.

It might be right, for all I know -- but it's what I've done all my life.  The guest BR is at one end of the house and I'm assuming on the end of a long duct dedicated to it.  Closing that duct at the END, rather than dampering it at the BEGINNING, shouldn't affect the back pressure measurably since it's at the other end of the house from the furnace.

I think.

To your credit however -- and I've explained this to Mrs NoCo without success -- with the thermostat in the hallway, shutting off the back bedroom doesn't actually save us any heating costs.  The hallway still has to reach temp, and it's the only part that matters to the thermostat.

NoCoPilot wrote:

Never heard this before.

It might be right, for all I know -- but it's what I've done all my life.  The guest BR is at one end of the house and I'm assuming on the end of a long duct dedicated to it.  Closing that duct at the END, rather than dampering it at the BEGINNING, shouldn't affect the back pressure measurably since it's at the other end of the house from the furnace.

I think.

That's what I'd always done, until an HVAC engineer told me about it. He proved it by measuring the air flow in the dining room vent and then closing the vents in the back bedrooms. When he again measured the air flow in the dining room, it had decreased.  It makes perfect sense: if you close one vent, anywhere, it decreases the total volume of the duct work and increases back pressure. And it doesn't matter where in the duct it is closed - the furnace still sees it as closed.

He even checked the opening below every interior door. He said that if you don't have enough space below a closed door it can affect the system's efficiency.

Huh. Guess that makes sense.

Let me get out my calendar and mark the day.

NoCoPilot wrote:

To your credit however -- and I've explained this to Mrs NoCo without success -- with the thermostat in the hallway, shutting off the back bedroom doesn't actually save us any heating costs.  The hallway still has to reach temp, and it's the only part that matters to the thermostat.

We have gas fireplaces upstairs and down.

The reason I'm not setting the new thermostat to be "on" all during the day, now that I'm retired, is that I usually hole-up in my music room downstairs, or the living room upstairs, and pop the fireplace on instead of heating the whole house. Probably saves something.

Although, a lot of it goes up the flue too.

We have a gas fireplace in the living room, but never use it.

A few years ago, I had the furnace and A/C compressor replaced with high-efficiency, higher capacity models. Also had some changes made to the ducting. Our summer electricity and winter gas bills fell about thirty percent. The new furnace is 98% efficiency. It doesn't even require a flue - just a piece of two-inch PVC for a vent, where the old furnace required a two-walled flue.

Okay, I've got to say it. The one thing that would keep me from buying a Nest thermostat is the non-replaceable battery. Of course they don't call it non-replaceable; they call it built in. It eludes me as to why in the hell anyone could think that is a good idea. When the batteries on my old-fashioned thermostat get low, the thermostat pops on a little red light and puts a message on the screen to notify me. Takes about thirty seconds and costs a dollar to pop in a couple of double-As. What happens when the battery on the Nest goes bad? New thermostat? Probably cheaper and simpler than sending it off to have the battery replaced for about fifty bucks. I do not - and never will - accept the practice of using non-standard, non-replaceable batteries in any device. It turns an expensive piece of equipment into a consumable item. Not good.

My understanding -- and it might be wrong -- is that the thermostat runs off a small voltage on the furnace control wires. If it has a battery, that's just for maintaining settings in a power outage.

At least, that's the way I hope it works.

Not all thermostats work the same way. It's possible that the battery in yours is just for remembering settings, but with the incredibly low price of flash memory, I don't know why that would be necessary; seems more rational than keeping some RAM hot all the time, but that's still possible. Some thermostats use the batteries for all their operations and the 24V is just switched for the furnace.

In your case, I would guess that the 24V supply is used to keep the battery charged and the battery is used for all the programming and furnace control functions.

But it doesn't matter much what the battery is used for - it still has a limited life span and can't be easily changed.

All I know is the thermostat was dark until I connected it to the furnace wires.  At that point it leaped into life without me having to turn any switches.

And when I was installing it the instructions said to turn off the furnace, with a switch or at the breaker, to avoid shorting out the furnace wires. I assumed that meant they carried a small DC voltage.