Garage Phase 2 – HVAC monitoring

In Part 2, I discussed installing a Pioneer mini split in my detached garage. In that post, I mentioned that the Cielo app that went with the Pioneer Smart Controller I installed in the mini-split fell short of my expectations of what I was able to see in terms of mini split usage over time. It’s not that the app didn’t have history of usage stats, it’s that with me keeping the mini split in freeze protection mode, the usage stats weren’t being collected at all. I think it’s considered more of a maintenance mode rather than active usage. I had expected something similar to what I was getting with my Nest thermostat with a usage graph but I just get “No usage” for ever single day even though I know it has been running.

On the left, the Nest app for my home’s HVAC. On the right, the Cielo app for the mini-split.

From here, I set out to come up with a way to monitor the usage history myself. I wasn’t exactly sure how I was going to do this. I thought of pointing my Wyze cam at it and watching for when the vent on the bottom was open vs. closed. But, I knew for sure that the vent was still open even when the heat was off. Changes in how much it was open might be too subtle to detect. This approach seemed way too difficult.

I have long had a Raspberry Pi version 2b with OpenHab running on it for home automation needs; controlling lights and so on. I also had integrated into it some old Oregon Scientific temperature sensors. They are the type where you have a temperature base station with a display for the current temperature and the ability to have remote temperature sensors which communicate wirelessly back to the station.

These remote sensors communicate via RF back to the base station and I found that it was possible to get an add-on board for the Raspberry Pi to receive those same signals. With a little programming, it was possible to capture and decode those broadcasts and to log them to a database on the Raspberry Pi. I did this project several years ago so I already had everything in place. I might actually cover that setup in more detail in a future post.

I reorganized my raspberry pi setup a bit and started to collect both outdoor and indoor (garage) temperature and to save the values every minute. In realtime, I can view the current temperature, humidity and battery status of each sensor right in the OpenHab app. And, I can also see a chart of historical temperature values over different time periods.

On the left, OpenHab displaying the raw data collected from two temperature sensors. On the right, a graph of temperature for the last 24 hours.

The result was somewhat surprising. I was clearly able to see a sawtooth pattern in the garage temperature. Visually, it was pretty easy to tell when the mini split was heating and when it was not. At this point, I was pretty sure I could write an algorithm to calculate when the heat was rising and when it was falling. And, I could hold that trend data against the outdoor temperature as a further verification of a temperature rise due to heating. And, conclude from this how often the mini split was running.

Since the OpenHab charting features were a little more basic than I needed, I exported all of the raw temperature data and used the Plot2 application on MacOS to graph it. The result was pretty neat. I could definitely see the cycling of the mini split to keep the temperature at 46°F. The temperature sensor is physically a few feet away from the mini split and a little below it so I think that accounts for the difference in the temp being maintained at what appears as slightly under 46°F, the freeze protection setpoint.

Indoor and outdoor temperature for the month of January 2021

From here, I then brought the same data into Excel and worked on my algorithm to figure out when the heat was on. Since I had data on a minute-by-minute basis, I was able to determine if the heat was on for each minute-by-minute interval. I was able to overlay the heat data onto the original plot in order to visually verify that my algorithm was accurate and I was correctly capturing the heating periods corresponding with the rise in temperature.

Two day temperature history with calculated heating periods overlaid.

In general, I thought my algorithm was doing pretty good. There are a few minutes missed here and there. I will definitely revisit it to do more tuning once I have more data. With the data in Excel, I then created a pivot table to compare hours of heating per day with the average outdoor and indoor temperature. I also plotted that data.

A pretty cool observation from this is that, as might be expected, the demand for heating is nearly exactly inversely related to the outdoor temperature.

II was also interested in determining any impact on electricity costs related to heating the garage. While I hadn’t started capturing the minute-by-minute temperature data until the end of December, I had starting running the mini-split in late November. I even had used it to heat above the temperature set by freeze protection mode in late November while I finished work in there. So, I set about to next figure out how much more I was paying in electricity.

To do this, I went back to my historical data for electricity usage. Comparing the average kWh used per day for the two months that the mini split had been in use (December and January) to what I had captured for the preceding 10 years, I was able to observe the following trend data.

Historical electricity use for December and January for the last 10 years

This data spans many different usage impacts in our home; conversion from CFL to LED lighting, switching from old school thermostats to the Nest Thermostat, the addition of gaming desktops, and more including an increase in our electricity usage due to the pandemic. Simply put, we are home more often. Clearly there has been an increase with the addition of the mini split, but not so dramatic that I am really worried about it as it did not put us at all-time highs.

To take a different view of this, I looked at the delta in average daily usage per month between the last 15 months each compared to the same month of the preceding year. This picture also does not show me anything alarming about the electricity usage added by the mini-split.

Year over year historical electricity usage change for the past 15 months

What it does show is that in late 2019 and early 2020, we were on a good path with each month showing a decrease in usage vs. the same period of the preceding year. That is until the pandemic hit in March and we were all at home. Note that July is always a wild card as cooling is a major contributing factor to our electricity use so I just view this anomaly in July as attributable to less A/C usage. Without July, the latest usage numbers for the last two months with the mini-split are not that out of line with the proceeding 7 months.

All things considered, I’m actually pleased with the limited impact that the mini-split has had on our electricity usage. As, I conclude this post, we are now in one of the coldest periods of our winter thus far. We’ve been seeing temps in the teens and single digits for a few days. I think my next post will be on this more severe cold weather performance of the mini split after I capture some more data.

What I used for this project –

Garage Phase 2 – Adding heat

In Part 1, I went through the insulation process. I achieved what I thought was a good enough result for this space – R15 for the walls, R30 for the sloped ceiling and R45 for the rest of the ceiling. Given the heat loss of the garage doors and concrete slab, this seems more than acceptable.

Insulation almost done. You can see the beginnings of the mini split install.

After the insulation install and with winter quickly approaching, I decided to get right to installing a mini split heat pump. There was a long lead up to this step which involved picking what to install. I decided to go DIY as this project would have been too expensive to justify otherwise.

Equipment choice

The conventional choice would be go to the standard DIY option, Mr. Cool. What I found as disadvantages of that option steered me to look elsewhere. These being the fixed length of the line set (at 25 ft.) and the lowest outdoor temperature at which it will heat which is 5°F. While we rarely get temps in my locale in the low single digits or below, I figured a mini split with a lower operating limit would be better in the range that I am looking for it to operate in.

As a result, I choose the Pioneer WYS series as they are still relatively DIY friendly and have an operating limit for heating at -13°F. Like the Mr Cool and many other mini splits, this model has a freeze protection mode. Most mini splits have the ability to heat in the range from the low 60’s upwards to the 80’s or even 90°F’s. The intent of freeze protection mode is to keep your space above freezing in order to prevent frozen pipes during periods when you are away. With the Pioneer, freeze protection mode keeps a constant 46°F. And, there’s no reason you can’t run it in that mode all the time, right? We shall see. Actually, we’ll evaluate the real world performance in a future post on that exact topic.


In order to determine sizing of the mini split, you can use a very basic calculation solely based on square feet all the way up to a full calculation based on Manual J. There are calculators that are between these two as well. I found that the complicating factor in using these generic, simplified calculators was that, being a garage, my room was not standard. Any calculations should account for the garage doors, the concrete slab floor and the ceiling height.

I found a good compromise in the calculator here. It allowed me to add the specification that I thought made this complicated but was simple enough for me not being an HVAC pro. It also allowed me to try many what-if choices varying things like design temperature, type of ceiling (because I didn’t know if my tiny attic would qualify as such) and to assess the impacts of keeping the space well heated or just heated enough.

To confirm these findings, I did find a Manual J calculator at that didn’t seem to require a PhD in HVAC and had a free option that seemed to give me what I needed.

My conclusion was that 12k BTU/hr seemed appropriate for maintaining the heat at 46°F through the winter months. If I decided to use it for cooling in the summer, this size would be appropriate for that as well.

Install process

There are lots of good videos on YouTube to guide you through the install so I won’t cover all those details here. Instead, I plan to cover the things that I wish I knew before I did the install.

I purchased my unit from Pioneer Mini Split Store. It shipped to me on a pallet and delivery by the shipper was seamless. The driver used a pallet jack to put in right into my garage.

This was an exciting day when this arrived. I’v3 dreamed about having a mini split for years!

Planning. I spent a lot of time planning the location of both the inside and outside units so that I would not have any coiled line set. I created a cardboard template for the outside unit. This allowed me to position it where I thought I wanted it considering the stud locations required for the mounting bracket. I wanted to get the vertical parts of the wall bracket to be on studs. And, with the walls unfinished, I was later able to install blocking in the wall for the horizontal bracket piece.

I used a couple pieces of twine cut to the length of both the line set and the control wire in order to confirm that my proposed location was good.

Working out the equipment location. Obviously, the mocked up unit would go outside and the line set would not follow the path of this draped string but would drop vertically, make a 90° turn and then horizontal to the outside unit. I held it in place to confirm this.

The flaw in this planning was that it was all in the same plane and didn’t take into account that the mini split would be mounted several inches away from the house. Luckily, I had planned for a little extra length at each end for adjustments.

Wifi module. I purchased the Pioneer OSK102 wifi kit from Amazon as I wanted to make sure that I had control of the Mini Split from my phone. More than anything, I wanted the ability to monitor it to see when it was running. This was based on my experience with the Nest thermostat, where that app helped me understand how my choices for temperature mapped to how often and how long our furnace was running (and ultimately allowed me to make money savings changes in how we heated our house). It actually turned out that the Mini split itself came with a wifi module.

Both of these wifi kits were slightly different. The Pioneer OSK102 wifi kit included a module which plugged into the USB port in the circuit board in the front panel of the indoor unit. The Pioneer OSK102 is controlled via the Nethome Plus app. The Pioneer Smart Controller kit (TST-APWIFICWPD), which came with the mini split, is a small circuit board which replaces the existing board under the front panel. It uses the Cielo Home app.

Pioneer SmartController kit (TST-APWIFICWPD) box. Circuit board it replaces is pictured. Also seen is the tool that I created to install the drain plug.

I was able to try both to see which I preferred. I ultimately went with the Pioneer Smart Controller because I thought the app was better. I was not able to figure out how to turn on freeze protection mode with the Nethome Plus App. Since it’s been a couple months since I used it, I honestly can’t remember if the app had that feature but I seem to remember it not having it.

Ultimately, though, the wifi kit turned out to be of very little use to me. It turns out that when the mini split is in freeze protection mode, the Cielo app shows the Mini split as off. As such, the history section of the app shows “No usage” for every single day. So, my hopes for a Nest-like graphic visual of when the heat was on each day were not met.

Vacuum Port Adapter. This is the second thing that I bought that was redundant. The mini split itself came with a vacuum port adapter. This is required to attach the vacuum pump to the mini split. I think that I got this with the mini split that I purchased because it included an installation kit. This may also be the reason for in inclusion of the Pioneer Smart Controller. If you are installing another brand or the Pioneer without the installation kit, you will need this adapter.

Drain plug removal/install. The Pioneer mini split has two places where you can install the drain hose. In order to have the drain hose, line set and control wire exit the mini split on the side required by my installation, I had to use the alternate drain port. This meant I had to remove the factory installed drain plug from the port that I needed open and move it to the currently open port.

The rubber plug is easy to remove but difficult to install. Actually, I tore mine trying to push it into the hole with a nylon tool. It was difficult to get leverage and to compress it into the hole. What I found was that I needed something to push it which I accomplished with a custom tool that I made. I simply took the handle from a foam brush and used my bench sander to taper it to fit into the plug. See the photo above for this tool.

Torquing connections. The torque wrench that I purchased for this project was great for the 1/2″ line which required 26.6 lb-ft of torque. It did not meet the need for the 1/4″ line. While the requirements for this was for 11.8 lb-ft and the wrench had a low setting of 10 lb-ft, it just didn’t work getting to this value so close to it’s lower limit. The adjustment grip on the handle did provide some positive feedback that there was tension as you turned it, but this went away under 12 lb-ft as it just seemed loose. I still moved ahead with the tightening which was difficult with such a small wrench head. I ended up over-tightening as the limit click was never achieved and I straightening the flaring right out of the tubing.

Thankfully, I had purchased a flaring kit as a backup as I had heard that the factory flarings were often imperfect. I was at first pleased that my flarings were all perfect from the factory but then thankful I had this kit so I could add back the flaring I took out of the tubing.

The small and large diameter tubing ends which you connect the line set to on the inside unit were not the same length. This mismatch in length resulted in an equal mismatch on the outside unit. Since I had the flaring kit, it was a no-brainer to cut the 1/4″ tubing by the approximate same difference prior to making the outside connections in order to get everything to look clean. If I had to do it over again, I think I would have cut the extra off the line set where it attached to the inside unit where the lengths of the factory pieces were different and not let that difference transfer all thw way through to the outside unit.

The result

I am very happy with the end result. I got the outside all buttoned up before the cold weather really set in. It was never clear to me how the nylon wrap was supposed to stick to the line set so I ended up zip tying each end.

The final install

On the inside, I did get unit almost centered on the wall with about 8 feet from it’s bottom to the floor. I primed and painted a piece of drywall for behind the inside unit. I then realized I had enough time left in the fall to work in my newly heated garage to install some drywall on the walls. Since I was working alone, I focused on the lower parts of the walls. The ceiling and upper walls will wait until next year.

The 2014 GT and 2008 GT/CS won’t freeze this winter!

Next up, heating usage monitoring.

What I used for this project –

Garage Phase 2

This is what it looked right after the build. It will never look this again!!

At the end of the summer I transitioned from house projects to garage projects. I couldn’t help but think ahead to the coming winter and enhancing the space used for storage of the Mustangs. Ever since I had the 2 car detached garage built in 2015, I have wanted it to be a decently warm place to store the cars. With it being not insulated or otherwise finished inside, it held no heat and pretty much maintained the same temperature as that outside.

The walls are 2×4 construction and the sloped part of the ceiling is 2×8. In order to increase the thickness of the insulation I could use, I added ripped 2×4 to each rafter to get effectively a 2×10.

Rafters with extended width

I considered thickening the 2×4 walls but the complexity and time involved especially for handling the window and door openings, seemed more than the added benefit that the additional thickness would provide. Although, I did have to address the upper part of the walls as the framing was done with the 2×4’s in a non standard orientation.

End walls with added framing (lighter in color)

With this framing done but before I insulated, I also did some other things –

– I moved some of the electrical that i had an electrician install to where I actually wanted it installed. I also added some ceiling boxes for future lighting needs as well as a box for a future celling fan.

– I added some framing in the corners for future drywall screwing.

– I added a catwalk across the top side of the collar ties using some extra 1/2″ plywood I had around. It’s a little sketchy to crawl around up there as it flexes but the need for going up there is very minimal.

I framed an opening in the collar ties. Even though I have no use for the limited space in the attic, I figured it was pretty trivial to add this now rather than entirely sealing off the attic space. As it turned out, it was useful to have this access as I added more insulation from above after the ceiling was insulated.

Approximately 32″ x 32″ opening for attic access

For insulation, I went with mineral wool rather than fiberglass. With it, I found that I could get a slightly higher R value for the same thickness. I had purchased a small amount of Rock Wool a few years ago and found it easier to work with than fiberglass in the ability to cut and shape it. Since that time, pricing of mineral wool has dropped to be the same as fiberglass. So, using it was a no brainer.

I started out with Owens Corning Thermafiber mineral wool. Handling it, even gently, resulted in it just starting to disintegrate and break apart. Working with a piece of it over my head resulted in my being covered with particles from it. I found that once it was in place, it was near impossible to remove it should you not get it exactly where you want it. It is just too brittle. Luckily I had just purchased one bundle to try it out. I would have returned it but since it came compressed in the bundle it was not possible to get it back into the bag so I just threw it out and took the loss.

I then switched back to using the Rock Wool brand. This was perfect. Much less fallout from handling it, and even the ability to remove a piece and reposition it if needed. I cut it with a handled hacksaw blade and was able to cut angles, electrical box cutouts and other cuts in order to fit tightly to the framing.

Insulation nearly complete. Furring strips installed just in case

The angles of the ceiling presented a challenge and resulted in this project taking a lot longer than I ever had anticipated. Because drywall was possibly not in the plans for this phase, I installed furring strips across the rafters and collar ties to keep everything in place. While the insulation had a pretty good friction fit, it just added peace of mind that things will stay in place.

In terms of air flow, I used Owens Corning raft-r-mate vents. It was possibly overkill, but I added them in every bay. This required two pieces which I did not overlap but separated with a two inch gap. This was based on research that I did on these vents. I also learned that coated staples should be used but, since I couldn’t find them locally, I went with stainless steel.

Note some of the cutting that required lots of time. Here, fitting around the collar ties

Relative of the attic space, I was thankful for the access that I created for it as I was able to add another layer of insulation on top of what I installed between the collar ties. I also used some of the many extra cut off pieces I had to fill in the space over the catwalk.

Unusable, but well insulated attic space

So, the end result is a pretty well insulated garage with the walls being R15, the sloped sections of the ceiling are R30 and the rest of the ceiling is R45.

Next up, adding heat!

What I used for this project –

Recycling at its finest

Chris writes:

I was doing some kitchen work and was removing an old and dated cabinet to make room for a bay window. I needed a place for my power tools so I decided to make it worthy of placement in the garage. I spray painted it with a few coats of Krylon Fusion paint made for plastics. (Patriot blue, looks like Ford blue) It’s made with the same adhesives found in model glue so no sanding or priming is needed. Still, I gave it a once over with 220 sand paper. I bought a Mustang window decal on ebay for $12 and spent another $7 on new chrome hardware. It now holds all my power tools. I bored a hole through the bottom and ran the cord out for my cordless drill battery charger. Nice weekend project.

Chris' cabinet before

Chris' cabinet after

Very much like what I did with the cabinets I used in my garage. The major difference is that I picked up mine at a garage sale for $5 apiece and they were orange! Another difference…Chris took the time to tell us how he did it. Thanks, Chris!

Garage remodel

Some of the people who I work with joked with me that I must be out of home projects to be doing a garage remodel. Well, not really. If you are into cars as much as I am, which I figure you must be if you are reading this site regularly, you know that it is not entirely out of the question to redo your garage when, say, the porch off the back of it is in serious need of a repaint.

I love our house but the one thing I would do differently if we were buying again would be to get a 2+ car garage. My one car garage is good size but was, until recently, the area used to store yard tools and the like. Here’s a shot of it at probably its worst.

Garage before

Still room for the car but barely. Note the low-tech car ramps which I parked the car on as a normal practice so I didn’t have to store them elsewhere. This resulted in a question from nearly everyone who entered my garage about their purpose as if I knew some secret to car storage that required storing it with its front end elevated. The other thing about these ramps is that when my brother saw them he said he had built a set just like them. I guess great minds think alike.

Well, this was the year of the shed. It was a purchase that I have been thinking about for several years now. That allowed me to get nearly everything that was non-car related out of the garage. I also painted it. I am pleased with the result.

Garage after

I repositioned the cabinets from the side wall onto the back wall and added a took bench I had in my basement. I did this work during a week off I had in October. I didn’t have the idea for doing the lower wall in red until the Friday before I started the painting.

The black stripe is not just cosmetic. It is functional and serves as a sort of chair rail. I prefer to call it a “door rail”. It provides a layer of protection between the car door and the wall. My walls are textured plaster on one side and a brick chimney on the other. Neither are very forgiving.

The rail is actually not the same thickness all around. In the 7 or so feet on each side of the garage, where I deemed that a door is most likely to open, the rail is made from 5/4″ x 4″ board. It tapers to 1/4″ x 4″ board to cover the rest of the garage. This picture of the “door rail” in progress should give you a better idea. The top and bottom edge are painted black.

Garage door rail in progress

I then applied a rubber surface to the board. The rubber is actually just standard black cove base like you would use with a vinyl floor. I cut the bottom part of the base (the cove) off to make a 4″ wide rubber strip. This approach allowed me to have no exposed screws. All screws are countersunk under the rubber molding which, in turn, is glued to the board.

In the above photo you can see the rubber strip on the right side on a board setup I was using to trim the bottom off. Below you can see the finished result. Note how the “high point” on the door edge meets the rail nearly dead center. Yeah, I’m pretty anal. This height was optimal for the Mustang but also works well with the other cars we own.

Garage door rail in progress

The Mustang now fits nicely in the garage with plenty of room on either side to pass by.

Garage with Mustang

I am still in the process of decorating it with various Mustang signs that I have. A future phase might involve addressing the floor. I am concerned that epoxy might not last long. I have seriously considered Race Deck flooring as well as the Moto Floor alternative they sell at Costco. Although, both are a little outside of my budget for now.