2017-12-01 The Tale Of Two Thermostats – Part 4

I know.. I know.. How many parts are there to this story? Believe me.. I wish I knew.

Yesterday I had a super productive day on most fronts including having a major breakthrough on my HVAC issues. I won’t rehash through all the facts and history behind this. I’m cutting right to the chase.

The chase is my cat like instincts going after the clever mouse of electricity and wiring with an acute attention to details and a heavy dose of patience. This post could easily have been titled “Troubleshoorung 101”.

The trick to it is truly in having a logical pathway of isolating variables, changing just one thing at a time, and monitoring the results.

Yesterday things got serious. I started a log including timing, what I did, and the result.

I swapped wires, messed with settings, went up and down my basement stairs about a hundred times, and had two chat sessions with Nest support. Again, I’ll forego most of the details and just share my results/conclusions.

The Nest people were helpful in providing additional ideas for troubleshooting but in the end they were wrong about my problem. They both concluded I had a faulty Nest unit and that I needed to return it and get another. Based on my observations, I was skeprical.

I even asked very directly if the Nest was compatible with my Honeywell HZ322 zone control board. The answer was “yes” and that answer was either wrong, or the root cause of ALL my woes Is that damn board has gone bad.

Both thermostats can’t function because of insufficient power supply. Coincidence? I think not. The ultimate test was me altering the wiring in my furnace room to bypass that Honeywell completely and hook the Nest up directly to my furnace. Once I did that and turned the power back on.. Bam, the Heat goes on!

My first thought? “That’s Balls out amazing”. It really does work and the Nest is not the problem. I have narrowed that down to one off two things.

1. I need to replace my zone control board -or-

2. The Nest requires a Common (“C”) wire to close the voltage loop and provide enough power. (Or both)

On the Nest website in the support section there is a page on this. There’s a short list of 10 make/models of zone boards that require the C for the Nest to work, but mine is not on the list. The HZ311 is, so perhaps mine just hasn’t been “discovered” yet. Wouldn’t that be awesome if I was the first one reporting it??!

So the next logical step in the process (which by the way is partially dictated by cost) is to get thermostat wire that includes the C (because of course mine doesn’t).. and fish it through the wall.

I’ve also been researching replacement zone boards and considering most everything I have including sensors, dampener control, upstairs thermostat is all Honeywell, I’ll likely go with buying the same one. If it comes to that.

I’m confident it will come to that. No matter what happens with this Nest thing, the other zone/thermostat is not wired and requires that wireless receiver which doesn’t work because of the power issue.

Today’s agenda? Return the Nest, get some wires and wire cutters, and also apply for three jobs. If I do all that, I’ll be happy with my efforts.

Oh.. I’m returning the Nest not because I don’t like it, but because I’m researching options and not sure I’m going to stick with that choice.

And the “Heat Goes On”,

~Miss SugarCookie

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