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 […]

Read More →

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 […]

Read More →

Multizone Systems: The Single Flow Problem

Over the past several posts, we’ve been hitting on the big deal with multi-zone HVAC Systems. You can attain amazing levels of control over how hot or cold any given room is. That is, except for one problem: you can only really push one “direction” at a time without making things incredibly complex.   One Temperature Change Suppose most of your building is set around sixty eight degrees. Maybe one room wants seventy four and another sixty. The temperature outside is a warm but not unbearable eighty seven degrees. Our multi-zone system kicks in and sends exactly the right amount of cold air to exactly the right rooms as needed to achieve those desired temperatures. All sounds good, right? What if someone wanted their room to be ninety eight degrees? Maybe they’re curing concrete or they’re homesick for some equatorial inferno. This shouldn’t be a problem for our amazing system, right? Just raise the thermostat and hot air will come pouring into the room? We’ve been presenting the most straight forward, affordable, and common multi-zone system: one set of ducts, and one set of pipes. In order to heat that one room above the outdoor ambient temperature, the furnace and cooling system would be running at the same time. They would both be pushing hot or cold material into the building’s one distribution system. The air or water would mix and become the median temperature, something neither hot nor cold […]

Read More →

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 […]

Read More →

Multizone HVAC: The Ductless System

Multizone systems can be big, complicated, and a challenge to cram into small spaces. If you’re using hot and cold water for your heating and cooling, you need to install valves and actuators everywhere, possibly install a whole second set of pipes for a “dual pipe” system that meets any need, and make sure you can pump enough water to satisfy the beast. In forced air applications, you would have to tear apart your ducts to add the controls and fans, then spend ages locating and sealing every leaking part. This nets you a working system, but it could be better and easier.   The Central Problem We tend to centralize our HVAC hardware as much as possible. You do all your heating and cooling in one place, then send the air or water around the building. It makes a lot of sense. You only need one or two boilers for most places, even industrial settings. Put it all in one place and save on energy costs and complexity, except when you want granular control. With a central heat or cooling source, you need to add tons of controls to manage the flow hot and cold air. You’ll lose a lot of energy by sending air and water around too. Leaks in air ducts and pipes radiating heat into the open air pose annoying losses in efficiency. There’s only so much you can do to fight nature’s hell-bent desire to […]

Read More →

What is a Multi-Zone System?

Most residential and older HVAC Systems have one enormous flaw: They don’t provide a uniform or even well controlled environment. These simpler systems have one point of measuring temperature, and generally have to just hope that the single thermostat is a good representation of the temperature in the house. In practical terms, this means one room can be twenty degrees hotter than the rest of the building or a good draft from a single window can fool the thermostat into roasting everyone. This is the old way of doing things, from before we had cheap electronics and a mature industry to deliver on our comforts day and night. Take for example, my house. It was built probably in the late 1940s or early 1950s with hot water heat, two floors, and a single thermostat in the center of a house. This proves to be a challenge in the winter. The rooms first on the heating loops will become scorching hot. You open a window in those rooms and they become comfortable. The cold draft blows into the other rooms and they’re suddenly not comfortable. We might bake in the kitchen one night, whipping up a lovely ten to fifteen degrees of extra warmth, which happens to heat the thermostat. The kitchen eventually becomes comfortable, but the bed rooms freeze over.   Single Zone Systems This single-thermostat arrangement is called a Single-Zone system. There’s one data sample and one place all […]

Read More →