post: add HVAC overhaul in Home Assistant

Author: XerxesDGreat

_posts/2025-07-02-hvac-overhaul-in-home-assistant.md

@@ -0,0 +1,119 @@
+---
+title: HVAC overhaul in Home Assistant
+date: 2025-07-02
+# categories are Family, Photography, Places, Projects, Reviews, Software, Thoughts
+category: Projects
+tags:
+- homeassistant
+- automation
+- smarthome
+- climate
+media_subpath: /assets/img/posts/hvac-overhaul-in-home-assistant/
+image:
+    path: preview.jpg
+    lqip: preview.lqip.jpg
+    alt: Credit to Sean D on Unsplash https://unsplash.com/@paus_d_
+---
+
+You know those projects where you start doing something and pretty quickly think "why am I doing this?
+Isn't the default behavior good enough? Why should I customize this?" If you _don't_ ever think
+that, then it's clear you've never gotten into home automation...
+
+Managing temperature in a home is what they call a "solved problem"; we have thermostats, they 
+keep track of the temperature, and they turn on/off the HVAC system to keep the temperature within
+a certain range, depending on the mode. So why do I feel the need to create a set of automations
+which do _basically_ exactly the same thing my thermostat wants to do?
+
+Well, to put it simply, I'm convinced that I can do it better than my thermostat can, based on the
+circumstances. Sure, that's probably the hubris talking, but I feel like my thermostat could... well,
+let's just say it could use some help. Lemme go through what challenges my system has and point out
+a few things I want to happen which aren't really happening.
+
+# The System
+
+First, let's talk about the system; what exists, some of the challenges I have, etc.
+
+## HVAC
+I have a two-zone system, upstairs and downstairs. We're only going to concern ourselves with the
+upstairs since downstairs seems to be generally fine. There are four rooms we're concerned with:
+main bedroom, office, Cora's bedroom, and the game room. The thermostat, an Ecobee 3 Lite Smart
+Thermostat is in the main bedroom, which also happens to be the coolest room. In summer the sun bakes
+the office and Cora's room, and they can be almost 10 degrees hotter than the main bedroom. Thus, if
+the thermostat is on AC mode set to, say, 77 deg, the main bedroom can be 75 during the day while the
+other rooms are 82 degrees or more.
+
+I installed remote temperature sensors (the SmartSensor for rooms, also from Ecobee) in each of the
+"satellite" rooms which can help the thermostat get a better idea of what the true temperature is,
+but it still will only cool to an average, meaning the satellite rooms will still be hotter than the
+average target temperature.
+
+On top of this, the main bedroom has a _huge_ register (12" x 12") and is right next to the system
+blower motor; thus, the bulk of the cooling airflow will go into the main bedroom, cooling that room
+even more effectively, bringing the average down without much impact on the rooms which really need
+it.
+
+## Flair
+
+To mitigate the above imbalance a bit, I installed some [Flair Smart Vents](https://flair.co/) which
+can adjust and redirect the airflow to different areas under its control. I installed these last year,
+and they made a noticeable difference in the comfort level of the satellite rooms; the system would
+close the main bedroom vent, redirecting all the cooling power to the satellite rooms. However, using
+this system had some other challenges, mostly around how to interact with the system. The only way
+to set room temperatures was either using the app (which is inconvenient and kinda clumsy) or by
+adding a thermostat-type device in each room (Flair sells some for $120 each, which seems super steep
+to me). Further, depending on the mode, if one wants to adjust the temperature manually/temporarily
+and changes the thermostat, the Flair system will just overwrite that, leading to confusion and
+frustration.
+
+## Why Not Just Crank It?
+
+Well, now I hear the question "why not just cool to something a lot lower, like 72?" While that would
+definitely cool the satellite rooms to something more comfy, there's a couple reasons we don't want
+to do that. First, we don't tend to find 72 comfortable and, if we average 72, the main bedroom will
+be _very_ chilly even if the satellites are not. Second, we don't want the AC compressor running all
+the time; we've burned out two fans since we've lived in this house (we feel like it's a fault with
+the hardware since we _really_ don't run the AC enough to justify that) and we don't want to continue
+that trend. Finally, we don't want the power consumption. While we do have solar (15kW system), we
+like having an offset so our bills are lower. Also, just generally using less power is a good thing.
+We feel the current system is inefficient so changing the way it functions, evening out the
+temperatures, is our first priority.
+
+# Desired Outcomes
+
+Now that we have a good idea of what the issues are, let's make a list of what we want to achieve
+with a solution. Note that where I say "cooling", I also mean "heating" in the winter, but really
+summer is the only real issue here
+
+## Must haves
+
+If the end result doesn't have these, we can consider it to be a failure. Further, a solution is
+considered "complete" if it does all of these things.
+
+- Per room temperature settings
+- Time-based temperature settings
+- Adjustible manually without an app
+    - If it's adjusted manually, it should go back to the regularly scheduled program at some point
+- Disables HVAC if windows are open (I'm not paying to cool the outside)
+- Balanced cooling; if the temp is set to 75, all rooms should be 75 (or reasonably close)
+
+## Nice to haves
+
+It would be great to do these things also, but it doesn't _have_ to; we can add them later
+
+- Pre-cooling the bedrooms at bedtime based on projected temperatures
+- Responding to PG&E high-usage emails by adjusting the temp settings
+- Separate "guest mode" (but this is probably only relevant for downstairs)
+- Away mode vs home mode which autodetects whether anyone is home
+- Tracking occupancy and changing temperature if nobody is in the room
+
+
+# Next Steps 
+Fortunately, we have everything we need to do all of these things integrated into Home Assistant. We
+have the aforementioned room temp sensors, thermostats, and Flair smart vents all hooked up, but we
+also have window sensors and occupancy sensors in all the rooms, the ability to read emails to a
+specific email account, and know when people are home vs not using the mobile app integration.
+
+Thus, we'll piece all of this together, bit by bit. This post got away from me a little, so I'll
+plan to do these in later posts; setting up what sensors we need, what helpers, and how to link
+everything together to make a fully integrated climate system.... 85% of which we could probably
+do natively in Flair and Ecobee apps, but where's the fun in that?