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 the heat goes so far as the furnace and plumbing are concerned. It’s a cheap, robust system with few failure points that gets the job done, but it’s not great for luxury or places of wildly varying temperature within the same building. You wouldn’t deploy this in a restaurant because the kitchen would throw off the thermostat. By the same token, an office with a few well shaded rooms and a few heavily sunlit rooms may face similar challenges.

Many people use this heating ‘system’ because it works, it came with their home, and until fairly recently migrating to anything better was still a very expensive endeavor. As of this writing, it’s 2017 and things are starting to change.


Multi-Zone Systems

The big-upgrade is to add zones to a heating system. This has been common practice in industrial and business spaces for decades. In these systems, multiple thermostats, fans, pumps, and valves control the heating effort across a building. If Zone 1 is starting to become too cold, valves can divert hot water just to that stretch of the system. In forced air installations, fans and dampers control the movement of hot or cold air.

Implementing all of this comes down to some modified plumbing or duct work, some extra equipment to control the flow of air or water, some extra thermostats, and an additional controller to manage the zones and furnace or air conditioner efficiently. On a five thousand dollar project, this might add $1,000 to $2,000 to the bill, but then go on to provide complete comfort for years.

This simple concept is gaining in popularity thanks to advances in electronics and manufacturing. In the 1980s, a multi-zone system would need some custom computer system or a custom program on a then-expensive and new desktop computer. We’ve come a long way since then. Small motors and actuators are getting cheaper, as seen by the recent boom in drone aircraft. Computers have become dirt-cheap, with numerous companies producing chips and board that overpower any eighties computer for $20. We also can’t overlook the rise of smart thermostats, which are amazing in multi-zone applications.

We’re living in the future.


When to Upgrade

The reason to upgrade is pretty straight forward: this is an AWESOME thing that makes your home or office more comfortable. The time to upgrade however, is something harder to hammer down. If you’re happy with the existing system you have, it may be best not to rock the boat. If you’re going to be replacing everything in a major upgrade, then that’s the perfect time to add in new zones. Going multi-zone on older hardware would otherwise, bring some additional challenges. Older furnaces and air systems may not be ready to accomodate the change in demand or the necessary electronics.


The Wrap Up

Did we get something wrong? Got a topic for us to cover next time? Let us know in the comments below!

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