Category: House stuff

We have an amazing coincidence of incidents happening with the house HVAC.

HVAC guys were out yesterday for a 6 month inspection of the system they installed back in the spring. Looks like everything was working fine, but they found some part in the condenser unit outside was overheating and needed to be replaced.

Connie noticed last night that the room temperature the Nest displays is considerably higher than what it feels like. The Nest currently thinks it’s 29°C (84°F) in the house, which it most definitely is not.

While researching the Nest issue, I discovered that a new firmware update was recently pushed to the Nest along with several other Nest owners reporting problems with their Nest overheating and showing incorrect temperatures.

No idea if any of these issues are related or just an amazing coincidence.

Pulled the Nest off the base plate, and both the back of the Nest and the base plate were feeling pretty warm, which I’m thinking is what’s throwing off the Nest’s thermometer. After leaving the Nest disconnected for a while, it had cooled down but the base plate was still feeling warm, just on one side though.

First thing I did was disconnect the Y₁, OB and Rc wires on that one side and left them disconnected until the base plate cooled down. Wires were reconnected one at a time, starting with Y, then OB and finally Rc. The base plate stayed cool until I connected Rc, when it started feeling warm again after a few minutes. Disconnected OB and the plate cooled down. Reconnected OB and the base plate warmed up again.

This makes me think there’s some circuitry in that base plate that might be close to shorting out or already blown like what this person found. Took it off the wall and had a look inside. Didn’t spot any obviously blown components.

Next step: put in a call to Nest and see if I can convince them I have a problem with my base plate and get them to send me a new one.

After the HVAC inspection last week, it turned out that the system needed to be replaced sooner, rather than later. There’s a refrigerant leak somewhere (“Coolant leak! Bridge we’ve got a coolant leak in the engine core!“), the evaporator coil is rusted and the fins on the outside heat pump thing are slowly dissolving away. Not quite anything I didn’t know, and fortunately we had planned and budgeted for its eventual replacement. We got the recommended three quotes from different companies, two of which failed Connie’s interview process (they lost a lot of customer service points). All the quotes we got were reasonably close to each other, decently priced and not outrageously expensive. Now that we’ve selected a company, we’ll pick an installation date sometime soon.

Since the HVAC is being replaced, we also decided this would be a good time to upgrade to a Nest thermostat. I know a couple of people around here who have one and they really like it.

It comes in a simple square box without a lot of decorations. A sticker sealing the box warns you to check their website for compatibility with your existing system before opening.

Inside is the Nest, which doesn’t really look like it could get any simpler.

It’s not that large, about 8 cm (~3.5″) in diameter and it’s clicky. It’s a giant button with an outer ring that turns. Underneath is the manual and the mounting hardware.

Installation seems pretty simple too and everything you need (even the screwdriver) is provided for you. The mounting plate even has a built-in bubble level so you can make sure it’s, well, level. Total genius.

On the back of the Nest, there’s the connector at the bottom to connect with the mounting plate. There’s also a micro USB port at the top which can be used to charge the Nest’s internal battery (and is also for service use). I wonder if the computer will see anything if I plug it in.

Looking forward to getting everything installed and getting the Nest hooked up and running.

Update: Plugging the Nest into my computer (Fedora 18) causes it to show up briefly as a storage device with a .pinfo file containing some XML in it. However, it quickly disconnects and goes into a connect/disconnect cycle. Running lsusb shows an unidentified device with USB ID 2464:0002. Perhaps the Nest is looking for somethings specific when detecting a USB connection, and disconnects when it doesn’t find what it’s looking for.

When I woke up this morning and the house was 28°C (82°F), I didn’t have a good feeling about it. The blower inside the house was running, but the heat exchanger thing outside was just making a buzzing noise but wasn’t running. Not a good sign.

After last year’s maintenance inspection, I was expecting that the unit had finally failed and was going to need to replace it. Today being a holiday, I wasn’t expecting to be able to get anybody out to check on it until Thursday or Friday, but when I called the company (Carolina Air Care) was able to send someone out this afternoon, much to my surprise. It took a while for them to get out here (busy day for them it seems), but once the technician got here it only took him one look to diagnose the problem: a blown capacitor on the heat exchanger. A quick replacement and the unit was up and running once again.

The repair wasn’t cheap, but it was a whole lot less expensive than what I was expecting. Hopefully this will keep things running a little while longer and give me a little more time to continue saving to replace the heat exchanger. I know I’m going to have to replace it soon. It would just be nice to have a little more saved up for it before replacing it.

When it starts cooling down, I’ll have them come out again for the annual maintenance inspection and see how much time I might have left on the unit. Hopefully I can get another year out of it before needing to replace it.

Had a preventive maintenance check done on the AC system for the house and they tell me the big heat exchanger thing outside will need to be replaced soon. The cooling fins have a lot of calcium build up on them and are starting to corrode away at the bottom. The guy who came out to do the inspection said it would probably last through the season but wasn’t optimistic about it lasting much longer.

Given that I’m sure they’d love to sell me a new unit, I take his forecasts with a few grains of salt. It’s pretty clear though that the unit needs to be replaced fairly soon as in within the next year or two.

So that looks like about $4000-6000 to replace. Ugh.

My unit must suffer from something location related, because my neighbours’ units on either side don’t seem to be suffering from the same problem. Their units look pretty clean and almost new compared to mine.

I wonder if spraying the fins down with CLR would help clean up the calcium buildup. I’m a little worried there might not be much left underneath the calcium and I’d end up making things worse. Spot test.

Time to do some research on these things and figure out what I need.