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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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 […]

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