What if the Thermostat Really is Wrong?

A thermostat can be ‘wrong’ in that it only represents the temperature in one area, and it’s a poor representation of the overall building temperature or it can be wrong in that it thinks a 100 degree house is currently 0 degrees. Over time, the temperature sensor inside a thermostat can begin to fail. It might be a small error or something entirely bonkers.   Diagnosing the Issue Thermostat issues can be caused by calibration errors, dirt, or complete hardware failure. In the case of dirt, there’s some build up over the sensor, insulating it from the real temperature. Calibration issues can develop over time as the system wears, reading differently as the sensor becomes less resistive or components oxidize, or other issues. There’s also those few occasions where the whole thermostat just loses the ability to read the correct temperature, and that could be caused by a million things, including age, wear and tear, or a power surge. Before we run off and panic, we first need to confirm there is an issue and just how big it is. We need to be sure the thermostat is the cause of the problem and not just a victim of some other failure. The first step in this process is to measure the actual air temperature by the thermostat. You can generally just hold up a thermometer by the thermostat and see what it reads. I’m a bit lazy, I just […]

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Why The Thermostat’s Wrong

Thermostats are a great technology in principal. They automate a simple issue: if cold, turn on the heater. Before thermostats, someone would have to either stoke a fire or open a valve for hot water to flow. By comparison, any automation should seam brilliant, but there is a slight flaw.   Single Point of Reference In most homes and even small businesses, there’s a single thermostat, and it measures the temperature in a single place. Even in a smaller home, this can lead to drastically different temperatures across the building. Typically a thermostat’s in the center of the building to get the best ‘average’ temperature. This average however, is almost never correct. In the case of my own home, we can actually measure the temperature difference between rooms. My room is the second on the heating loop, and consequently has some of the hottest water delivered to it, the most available energy. By the time this water has reached the kitchen and living room at the end of the loop, the water’s significantly cooled, resulting in a potentially 10 degree temperature difference. These differences can be exacerbated by design flaws. The bedrooms in this house, for example, have base boards that are about half the circumference of the rooms. This allows for a ton of heat to be left in these rooms. The living areas of this house however, have a much, much lower ratio. Those baseboards are only able […]

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Glas’s Growing Pains

The smart thermostat market is a crowded, complex mess of competing designs, features, and ideas. Some designers are integrating popular assistant tools like Alexa. Some are integrating with smart home standards like Z-wave to expand their ecosystem. There’s some out there that are just trying to enter the market before it becomes too crowded, regardless of how ready they are to do it.   Johnson’s Glas Last spring, Johnson Controls released a new smart thermostat of their own: Glas. They created a cool, futuristic design. There’s a transparent screen, support for multiple assistants, and a rare sensor in these thermostats: an air quality sensor. On paper, this sounds like a winner in the smart thermostat market, but there’s a catch: the software’s not quite perfect yet. Johnson has managed to put out the hardware of a really cool device, but it’s real promise is in the future, the features yet to come. Right now, reviewers and customers alike have come across some short comings we all hope Johnson will address in software updates in the months to come. Users have complained about the lack of support for remote sensors, the lack of custom events, and other shortcomings in just how much of their smart thermostat they can control. We’ve already seen over the past few months some improvements. Customers’ complaints have gone from the thermostat having bugs or being slow, to a desire for new features instead. The good news […]

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A 30 Year Old Smart Thermostat

We’re in an era of cheap, affordable, and common smart thermostats. You can walk into near any sort of hardware store and pick up a thermostat that thinks about the temperature in your building rather than merely following a program. The thing is though, the common, consumer technology we have today started life as advanced, expensive, and complex industrial hardware decades ago. The Grand Rapids Amiga The Grand Rapids Public School System used a Commodore Amiga 2000 to power their HVAC System for just about 30 years straight. This system was set up around 1985 or so when it was considered cutting edge. At the time, a cell phone probably weighed a good 20 pounds, a powerful computer might run at 7 megahertz (the first iphone was about 80 times faster than an Amiga 2000), and airbags were over a decade away from being mandatory in cars. This begs the question: how could such a system ever work? Like any computer today, the Amiga just had to be programmed. It had a special radio transmitter/receiver which would communicate with each of the district’s buildings’ HVAC equipment. It received sensor data and transmitted when to turn the heating or cooling on or off.  It was just like a modern thermostat, but in a bigger, more power-hungry package. What we find particularly incredible is that this system was built by one of the district’s students. Anyone can learn programming, plenty of people […]

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Why is my 2 Stage Furnace Always Running?

After our talk on short cycling, we came across people with the opposite complaint: their furnaces were running constantly. As opposed to constant short cycling, these people were experiencing some form of long cycle. Their furnace would fire up, warm the office, and then keep running. There would be constant, mechanical sound from the machine. This is exactly what it’s supposed to do.   Wasted Heat In a single stage furnace, the thermostat calls for heat, the furnace runs, and once the target temperature is reached, it all shuts down. This is horrendously wasteful. Your furnace has just  burned fuel or used electricity to get a heat exchanger red hot. When the furnace shuts down, that heat exchanger is still roasting, glowing red, but its not using that heat. The heat exchanger will just sit there, cool down, and an extra ten, twenty, or even thirty minutes of warmth has just been completely wasted. The excess heat in the exchanger will go into the ambient air in the furnace. It might heat some of the basement or perhaps the furnace will have a tiny bit less work to do next time. In any event, it’s resources spent that aren’t making you more comfortable. This situation is analogous to approaching a red light, flooring the car, and then slamming on your brakes. All that gas to speed up is probably being burned for nothing.   Using Idle Heat There’s not really much […]

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How to Pick a Thermostat

We talked about installing a Thermostat and a little bit of the install process. Today, we’re going to look a little deeper into the factors and reasoning behind picking the perfect thermostat for your needs.   The Key Factors What type of HVAC System do you have? Heating, cooling, multizone? What can your existing system support? What do you want out of your new thermostat? Efficiency, ease of use, programmability, automation? If you can answer these questions, you can begin to narrow down what type of thermostats will fit your needs. There is a wide range of options out there, from simple, old fashioned set it and forget it units straight up to smart thermostats that detect and learn the building’s occupancy over time. Let’s dig a little deeper.   The Existing Hardware Your first concern is going to be making the best out of the hardware you’re already using. If you own a multizone system, it would be a tremendous step backwards to install a single, old fashioned thermostat for the whole building. If you own a simple hot water furnace with some radiators in a single zone system, a multi-room thermostat is probably going to be overpriced for the limited returns it can deliver. If there’s a full heating and cooling system, that too needs to be factored in. There are thermostats out there which are heating only. There’s probably even thermostats out there which are cooling only […]

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How We Installed a Thermostat

Here at the Procure office, most of what we specialize in is pricing, product hunting, and the general theory of what makes your furnace tick. How’s a thermostat work? It measures temperatures and sends either digital signals or specific voltages over wires to make the system do your bidding. Yesterday, we got to actually trade some theory for practice. Specifically, I got to trade theory for practice. My home thermostat of 20+  years finally croaked.   My Symptoms It was pretty hard to miss that the thermostat had died. As it began getting chilly outside and as the house started to feel more like a meat locker, we followed common sense and set the thermostat. At least, we tried to. On day 1, we pushed the little slider to ‘heat’, and the screen stayed dark. On day 2, we changed the batteries. The screen remained dark. Pressing the buttons really did nothing, but after some bored tinkering and prodding, the circulator pump came to life. Heat restored. How much heat? We didn’t know. The home office was an inferno. Our cats refused to go anywhere near the baseboards they usually love to sprawl against. I put a fan in the window and even mother nature’s frosty 30ºF breeze couldn’t fight off the furnace’s heat. Our thermostat had developed a fever or it was nostalgic for the hot and lazy summer.   Other Symptoms of Failure When your thermostat fails, you […]

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Measuring the Heat

Have you ever wondered how your heating system knows to turn on? Or to turn off? You could say “the furnace controller tells it to” and “the thermostat tells it to,” but that’s not the whole picture, is it? We need a way to measure the temperature inside the furnace and inside our homes. It has to be durable, reliable, and affordable. It doesn’t have to be precise, but it must be right every time it’s measured.   A Complex Web of Technology There are a staggering number of ways to control a furnace through temperature input. A brief and nowhere near all-inclusive list of techniques include: Gas Expansion Tubes, Bi-Metal Switches, Bi-Metal Coils, Thermocouples Driven by a Pilot-Light, Thermistors, and of course modern IR Temperature Sensors found in your enthusiast-chef’s kitchen. These devices are all in some way sensitive to the heat. Bi-Metal systems expand as temperatures change. Measuring the expansion reads the approximate temperature. Gas Expansion Tubes have an internal change in pressure as temperature changes. The pressure can be used to calculate temperature. Thermocouples generate an electrical current when they’re heated. Measuring the current allows you to determine the temperature. Inside a furnace, they’re often heated directly by the pilot light or burner to read flame temperatures. Infrared Thermometers measure “Blackbody (Wikipedia Link)” radiation, but aren’t all that effective around metals or the air. And lastly, we have the humble Thermistor, which varies it’s resistance based on […]

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Multizone System: With Voice Control

We’re getting closer and closer to the day when I can walk into my office and say “Computer, Tea, Earl Grey, Hot. And crank up the AC.” While researching for our recent series on Multi Zone systems, we came across an interesting press release: Honeywell’s Smart Thermostats can work with multi-zone systems and they can integrate with Google Home, Google Assistant, Amazon Alexa, Apple Homekit, Samsung Smart Things, and the ever-popular If This Then That (IFTTT). This is a pretty incredible idea for us, mainly because it’s been in Sci-Fi since the 80’s and it’s finally becoming part of our day to day lives. The possibilities here are pretty near limitless. I could use IFTTT and a phone app to detect if anyone’s in the office. Office empty? Thermostat goes to a predetermined “low power” temperature. On the way to my office? “Ok Google, cool office to seventy degrees.” It’s a step towards being able to control our homes and offices from anywhere, with smarter automation, and become more of a couch potato when I don’t feel like walking over to the thermostat to crank it down a few more degrees. Automation like this has it’s risks and challenges, but as we’ve posted before: automating the environment can save time and money. Let it cool itself down before your employees arrive and automatically shutdown when they leave. Let the lights turn themselves off when we don’t need them. Let technology […]

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Multizone HVAC: Forced Air Systems

Forced Air HVAC systems are an ideal candidate for a multizone installation or even retrofitting the necessary controls to an existing system. With air-based systems, leaks are easy enough to fix and it’s pretty straight forward to add in dampers, sensors, and the central control hardware without majorly disrupting the system. In contrast, water based heating systems require the lines to be drained, soldering, and a lot of effort to seal leaks in tight spaces.   The Basics Your standard, single zone/whole building forced air system is going to come down to the furnace/air conditioner, a bunch of ducts, some sensors, vents where it feeds into the rooms, and probably a single thermostat. By adding some sensors and controls, this easily turns into a multi-zone system. All we have to do is block the flow of air in strategic locations and have some central hardware manage the strategy for where air should and should not flow. Blocking the air flow is achieved with a damper and an actuator to control it. These come in a variety of shapes and sizes to accommodate near any system. They fit in over other pieces of duct work and get wired into a central control that sets how opened or closed that damper needs to be, to achieve the desired temperature. In principal, these can simply be added as part of a new installation, or put in place of an existing piece of duct […]

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