Note: If you don’t have more than one thermostat in your house, then you probably don’t have zones to control the temperature of your floor. Then sorry this article is not for you 💔.
Being a 🏠 home owner comes with lot of perks and of-course the ‘unexpected expenses’. Until this point I had no idea what is a zone and now here i’m trying to explaining how to fix it. I feel it is important to give some context but feel free to skip it.
Our home has three nest thermostat one for each floor and ideally we should be able to control the temperature by floor aka zone. Beginning of summer we started to notice our second floor [ zone-2 ] wasn’t getting enough cold air from the compressor but the first floor [ zone-1 ] was getting cold air even when the thermostat was not turned on ( kept in eco mode ).
Part I: Nest 🌡️
Troubleshooting started by being on call with Nest thermostat tech support for 3.5 hours to check if the thermostats are working fine and signals are sent to “Zone Control Panel” successfully. I had nest app installed on my phone and all 3 thermostats were linked, This came real handy while troubleshooting.
Below is the troubleshooting chart, note that in all scenario Zone-1 was getting cold air 🥶 and hence highlighted with * mark.
So we identified the problem lies with Zone Control Panel or Zone Damper.
Part II : HVAC Tech Inspection
At this point i realized this is beyond my reach, so called the local HVAC technician for regular inspection and told him the problem. The dude took a day and gave me a quote.
It was 🤯, so i decide to take matters into my own hand. That being said, i started googling to understand “zoning”, “zone panel” and “damper” etc and connected all the dots.
Part III: Zone Control Panel
This control panel usually be located closer to heating and cooling system. In my case I had it in my basement, the panel was from Honeywell HZ3222. This panel can control ‘Power Open & Power Close’**. However if you have different one then it shouldn’t be a problem. I’m interested to test if all zoning is working whenever i make changes in the thermostat. Below is the resulting chart,
** 🟢 🔴 : Lights indicated on the zone control panel next to the listed zones.
** Power Open & Power Close: The control panel gives three wiring and out of which one is used for opening the damper ( M4 ), another one is used for closing the damper ( M6 ) and last one for common ( M1 ).
So the Zone Control Panel works great. Moving on to the next one.
Part IV: Zone Damper
The final piece of the puzzle. The hardworking zone damper and it’s motor which controls the air flow in the duct. My googling suggested it is often the motor dies and replacing the motor would do the job, there is also a great medium blog on it. But are we sure it is the problem ?
I removed the zone damper from air duct to checked if there is any rusted shaft, forcefully opened/closed the zone damper by moving the shaft ( the one is attached to the motor ). Upon investigation i found out it is not responding to the signals from control panel ( please refer control panel chart and zone damper movement ). At this point I am once again left with two more choice, ( i ) Replace just the Motor or ( ii ) Replace entire zone damper.
Part V: New Zone Damper
In my case it was later option as my zone damper was 10 years old and the manufactures have stopped manufacturing the old model. I emailed the company tech support to find the right newer model & placed an order with SupplyHouse. But there is a new problem, below is the dimension difference between new model vs old model.
If you pay close attention I cannot slide in the newer zone damper in place of older one as the newer one has width of 4" inch vs older one has 2 1/8" inch. Now i had to cut the metal duct by 2.25" inch ( with extra buffer ) more to slide in the new damper.
Part VI: Duct Work
After few hours of research i ordered these tools from Lowes & Amazon to cut and seal the duct.
It was harder to cut the installed metal duct in an angle but with trial and error i managed to cut it enough to slide the new zone damper. Wired M1,M4 and M6 ( as mentioned before ) and tested the air flow before sealing the air gap using foil tape, mastic tape to prevent any air leak.
Part VII: Investment
It was few days of research, frustrations, learning and talking to people lead to decent saving and most importantly i learnt something new.
