Nest thermostats
I have 2 floors and 4 zones for heating. Ac coming from the roof for the second floor and ac coming from the basement for the first floor. Our plumber is saying that I will need one nest per floor (2 zones each) and two additional ones for the AC (one per floor) Is that correct? I really need 4 Nest Thermostats???
brooklyntoqueens
in Heating 10 years and 7 months ago
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20 replies
concord | 10 years and 7 months ago
‘Not that I understand’
concord | 10 years and 7 months ago
Thanks masterplumber – great explanation (not that understand it all but get the essence). Very informative.
zackly76 | 10 years and 7 months ago
MasterPlvmber – That was the answer that I have been looking for for so long. Thank you so much.
steam_man | 10 years and 7 months ago
SteamMan drops his wrenches and stares at MasterPlvmber in disbelief and with gratitude.
Master Plvmber | 10 years and 7 months ago
In the late ’80s, I started taking heating courses given by the agency responsible for certifying the performance ratings of boilers and radiators before they were released to the public. The company was called the Institute of Boilers and Radiation (I.B.R.). At that time, in every course given, they would cite their own independent studies which showed that nighttime “setback” fuel savings were consistently negated when the difference between high and low period thermostat settings went beyond 4 degrees in 24 hours. In other words, when a thermostat was set to go from 70° during the day to 66° or lower at night, the energy (fuel) it took to regain that 6+degrees in the morning surpassed the amount of fuel “saved” at night. There’s a lot to the studies and IBR is now defunct and has been twice merged with larger national certifying agencies who have no agenda to stir up any controversy. It’s all just dry reporting now. The problem is that IBR only dealt with water-based heating systems, not warm air systems. Warm air systems make up roughly 85% of the heating systems in the United States. Got that? Only 15% of our country’s homes are heated with either steam or circulating hot water. Of those, about half are in the Northeastern U.S. Anyway…. Nighttime setback works better, i.e. its intended efficiency gain is more readily realized, when used with warm air systems. So now, because it applies to 85% of the people it reaches, and because it sells thermostats, this blanket statement continues to float around out there that we need more sophisticated thermostats, room by room, to start and stop our heating systems multiple times per day. It simply isn’t true for homes using water-based, or “hydronic”, heating systems and the system that benefits least of all is…steam. Steam heat works best when it cruises at one temperature. Circulating hot water works best when it can modulate the amount of fuel it burns to match the demand of the system based on indoor and outdoor conditions. The difference between all these systems basically comes down to reaction time. And before you get the wrong idea that warm air can be made more efficient than hot water heat using setback, it can’t. Hydronic heat is just inherently more efficient and comfortable, but far more expensive to install, than warm air. Hydronics affords far more options in zoning, flow rates, water temperatures, and flame intensity (in short, energy delivery) than warm air ever will. Now, here comes the Nest. Nest uses all of that setback technology plus a motion sensor to make additional deep adjustments when we’re not even thinking about it or asking for them. The fact that you can (counter-)manipulate it from your cell phone should be little consolation. For most systems, definitely steam, it’s just too much control. It’s too much to ask one device to do in a consistently efficient way considering the variety of lifestyles, heating systems and construction methods used in this country. Ask people who use Nest what they think of it and you’ll get these extreme answers ranging from elation for its impossible fuel savings to it not working at all. I often don’t know what to believe. I had a client tell me Nest cut his annual fuel bill by 60%. There’s just no way that’s possible unless something was remarkably wrong with the old thermostat or some other problem was in play before he changed thermostats. Not much has changed since the ‘80s with regard to steam systems. What’s changed with circulating hot water systems to make them more efficient has nothing to do with the radiators or thermostats. It all has to do with integral logic and “condensing technology” in the boilers. I can’t imagine putting more control in the hands of users is the best thing. For this reason, I believe IBR’s studies still hold a great deal of truth. All of that said, Honeywell was never going to be outdone at their own game by Nest for long so their Lyric and Red Link stuff, as mentioned by steam_man, are getting a lot of attention in this industry. I’ve used a lot of words here to not really answer your question, but people ask me all the time and these are the thoughts that run through my head when I inevitably give my non-committal opinion.
brooklyntoqueens | 10 years and 7 months ago
Master Plumber, do you like the nest or do you have mixed feelings as many others do?
ellenlourie | 10 years and 7 months ago
Because it is hip, and monkey business. It proves that people will pay lots of money for something they can buy for less.
steam_man | 10 years and 7 months ago
Good Lord. Honeywell IAQ. RedLink or Wi-Fi all the way. Lyric may be a better way to go here. Why are people in love with that shitty Nest t-stat?
curated | 10 years and 7 months ago
If you are wired for 4 zones you would need 4 Nest thermostats. It will be cheaper to buy 4 Nest thermostats and use the existing wiring setup than it would be to have the place re-wired. http://brownstoner.staging.wpengine.com/curated
ellenlourie | 10 years and 7 months ago
Yes John, this is what I meant.
Master Plvmber | 10 years and 7 months ago
I don’t know. I may not be reading this properly, but the bottom line is you could have one thermostat for each zone (zone = individually conditioned space). You can’t have a thermostat react for a space in which its ambient temperature is not being read by that device. It won’t work right. Ever. You could argue a point about remote sensors but it’s the same point to make. The sensing device (or thermostat) reads the ambient air temp and activates the appliance or zoning device that conditions that particular space. If you’re piped for 4 separate zones of heat, I don’t see how you’d want to avoid having 4 thermostats. If any/all of those 4 zones also receive air conditioning, then you could share a heating thermostat if it also allows for the cooling operation, such as the Nest does. That said, Gennady, who says everyone is wrong about everything all of the time, brings up a point about using different types of technologies other than room air thermostats. Outdoor reset and non-electric zoning devices are, in my opinion and I’m guessing his too, a better way to go for heating, but it takes some getting used to and a bit more tweaking on setup.
presidentstps | 10 years and 7 months ago
So you need at least 2 thermostats — one for each zone of AC. . For the heat, you can either just do what I think Gennady is suggesting and not use thermostats at all but instead rely on your boiler’s outdoor reset and have the heat running constantly once the temp outside drops below a certain level (the outdoor reset will change the temp of the water for your radiators or radiant floor piping along a curve). Or add thermostats for each of those zones. Or link the heating zones with the AC if possible or with each other if you want to keep it simpler and you don’t want to control each individually). . I have 8 Nests in my brownstone, two per floor for each “zone” (some zones are linked). And I would strongly consider getting a different brand than Nest as the auto-learning isn’t great (I turned it off on all of them) and the connections to the WiFi are always dropping. Check out the Ecobee3 or Honeywell Lyric. Also seems like not a lot of innovation since they got bought by Google…
eman134 | 10 years and 7 months ago
Let the nest control a relay or contactor at each location which opens or closes the contacts for each unit. All the systems will be isolated from one another
fawn | 10 years and 7 months ago
My NEST thermostats control both AC and heating. But I do have a separate one for each zone. I’m in a 4-story with 3 zones and have 3 NESTs.
brooklyntoqueens | 10 years and 7 months ago
They are telling me that the issue might be wiring because each zone has a different wiring location but can’t we put some kind of sensor that send info to a single NEST?
brooklyntoqueens | 10 years and 7 months ago
Hey Bedstuyreno, do you have 3 different zoned (one per apartment) or just one sigle one for the whole building?
bedstuyreno | 10 years and 7 months ago
I heat the entire house (owner’s duplex and two floor through rentals) on one nest control.
transworld | 10 years and 7 months ago
You just need two thermostats. The Nest handle heating+cooling. In addition, you may want to consider this model: http://sensicomfort.com/ works good for me and way cheaper than the Nest.
eman134 | 10 years and 7 months ago
that is absurd…get a decent control electrician to wire the system