Heat Pump Water Heater

 Our 10-year-old natural gas water heater had about reached its life expectancy, and it was the last thing responsible for us paying money to the gas utility every month. We replaced it this weekend with a heat-pump hybrid electric water heater! A Rheem Proterra 50 gallon tank, in our case. It has both standard resistive heating elements, and a heat pump (hence "hybrid"). The resistive elements draw 4500 watts when you need heat in a hurry, but the heat pump draws only 400 watts. Interestingly, at 400 watts, a heat-pump-only version of this tank could easily run on a standard 120 volt 15 amp electrical circuit.

We have been working towards this since we replaced our natural gas furnace with a ground-source heat pump, but supply chain issues and life in general meant we kept the natural gas water heater for an entire extra year.

First we drained the old water heater and removed the exhaust flue:

I had to be careful of the coolant lines for the ground-source heat pump. Pretty inconvenient that they run down the middle of the mechanical room like that.

Then I wrangled the new water heater into place and plumbed it up.

Extra stuff: there's a 2" foam pad between the concrete and the tank, both for thermal insulation and vibration isolation. Then a drain pan to catch any stray water and direct it away from the pad toward the floor drain. I have a "heat trap" loop on the hot water output, to prevent convection or thermosiphon heat losses. There's a thermostatic mixing valve to prevent scalding, and an expansion valve (rather than a bulky expansion tank) which routes to a plastic vinyl tube manifolded with the condensate drains from the ERV and the heat compressor on the water heater. 

The Proterra tank is also an Internet of Things device, so I can schedule heating to run when our solar panels are likely to be producing extra electricity. I can also monitor how much hot water is in the tank, which has been my current pointless obessession since I installed the tank. The tank also reports how much electricity it consumes, but that hasn't really agreed well with the energy tracking I've done with my Emporia Energy monitor. I've seen other complaints about the energy reporting not being very accurate, so I'm going to give the benefit of the doubt to Emporia.

The old water heater used 12-14 therms of natural gas in a month, which is equivalent to about 350-400 kWh of electricity per month. We're on track to use about 60-70 kWh of electricity per month with the new hybrid water heater after the first week.

One tricky part is that we're planning to add a second "desuperheater" tank (already purchased, and taking up space in our finished basement) to scavenge heat from the ground-source heat pump and preheat the cold water before it goes into this tank. So the plumbing isn't final. But that will wait until the old natural gas piping is removed, to make room for the second tank.

https://precisioncomfort.com/home-comfort-product-choices/new-homes/heating-cooling-comfort-options-new-homes/geothermal-option-what-is-a-geothermal-desuperheater/

Controlling Dumb Air Conditioners with a Nest Thermostat

I've been using wireless ESP-8266s to control our portable air conditioners for a few years now. I decided to finally integrate them into the thermostat controls, rather than using voice commands or clunky timers.

Here's the previous post about setting up the ESP-8266s. This year, I'm going a step further, and designed and 3D-printed a case for the electronics:

Tying the portable air conditioners into the Nest Thermostat required a Rube Goldberg approach:

I initially tried wiring the Nest Thermostat to a resistor as a dummy load, so I could use software to see when the Nest was in cooling mode, and send a command to the portable ACs to turn on. But the Nest Thermostat didn't recognize the dummy load as legitimate at any of the resistor values I tried. However, it did recognize a relay I had puchased to turn on a humidifier.

So I used the relay to turn on a night light, and used a zwave "indicator light sensor" to detect when the night light was turned on (and thus when the Nest Thermostat was in cooling mode).

From there, I could use my smart home hub to turn the portable AC's on and off according ot the cooling status of the Nest Thermostat. Woohoo!

Update October 2020: I had to wrap my nice 3D-printed electronics cases in duct tape against the AC unit to keep my 3-year-old from stealing them, but otherwise this system worked really well this cooling season. I'm very pleased!

Whole-House Humidifier

Well, I think I figured out why our indoor humidity was so low:

Brianna is totally going to use this in her argument that we need a water softener...and now it is kinda hard to disagree.

New Location for the WiFi Router

Our coax cabling has been messed up since we moved into the house. I have only been able to connect to the internet through one cable port in the basement, which meant our WiFi router has been located in the basement. I have a few ethernet-only (no WiFi) devices in the basement, so this worked out for the most part, but we did not have a reliable WiFi signal in the backyard or the garage.

I finally got around to doing something abut it.

I traced the coax cables, and swapped the active coax cable from the basement connection to one in the Great Room. I put the cable modem, the WiFi router, and a small UPS in a nice box:

For the non-WiFi devices in the basement, I dug out an old WiFi router and flashed it with DD-WRT, and then put it in Client-Bridge mode. The non-WiFi devices plug into the DD-WRT router via ethernet, and then connect to the rest of the network through a wireless bridge between the main router and the client router. Took a while to get it properly configured, but seems to be working well now.

And we have a good WiFi signal throughout the back yard and well down the street now!

Automating the Air Conditioning - Step One: Control

Over the last couple years, a few articles about interfacing with IR controlled devices have popped up in my news feeds. Coincident with getting our new Air Conditioning Units (which have IR remote controls), a new walk-through popped up that seemed like something I could handle. The project required a cheap ESP8266 board (which has WiFi, some general purpose pins, and runs off micro USB for power), and an IR receiver and LED set for a total bill of materials of around ten dollars.

Here's another link to the project, to give credit where credit is due.

Once the parts arrived, it was time to get into black magic territory:

Here be Dragons

I got the Arduino IDE set up with no issues, and started playing with "sketches" - the code that runs on this little guy. I immediately ran into problems. It turns out you can't have spaces OR punctuation in the sketch name (which nobody bothered to mention in the tutorials I read), so my file "Brian's IR Emitter" had several problems right off the bat.

Once I got that figured out, I was able to load up the example IR recorder with no problems. I pointed the remote control at the receiver and started hitting buttons, with no idea what would happen next. Eventually I figured out (mostly by random clicking) that I needed to open the "serial monitor" to see the data the remote control was sending over IR. Here's the sample data from the "On/Off" button:

Encoding  : UNKNOWN

Code      : BBF4F9F (32 bits)

Timing[67]: 

     +9050, -4550     + 550, - 600     + 600, - 600     + 550, - 650

     + 550, - 600     + 600, - 600     + 550, -1700     + 600, - 600

     + 550, - 650     + 550, -1700     + 600, -1750     + 600, -1750

     + 550, -1750     + 550, -1700     + 600, - 600     + 550, -1750

     + 600, -1750     + 550, - 600     + 600, -1700     + 550, - 600

     + 600, - 600     + 550, - 650     + 550, - 600     + 600, - 600

     + 550, - 600     + 550, -1700     + 550, - 650     + 550, -1750

     + 550, -1750     + 600, -1750     + 550, -1750     + 550, -1750

     + 600, -1700     + 600

unsigned int  rawData[67] = {9050,4550, 550,600, 600,600, 550,650, 550,600, 600,600, 550,1700, 600,600, 550,650, 550,1700, 600,1750, 600,1750, 550,1750, 550,1700, 600,600, 550,1750, 600,1750, 550,600, 600,1700, 550,600, 600,600, 550,650, 550,600, 600,600, 550,600, 550,1700, 550,650, 550,1750, 550,1750, 600,1750, 550,1750, 550,1750, 600,1700, 600};  // UNKNOWN BBF4F9F

As far as I can tell, the remote for this particular model is pretty dumb. It sends out one command per button press, identical every time, and the AC unit decides what to do with that command (turn on or turn off, increment or decrement the temperature, etc.)

Next step was to swap out the receiver for an emitter (the IR LED). I made the switch, and tried to load the original poster's "emitter" sketch. And tried. And tried. And tried again. Nothing.

Turns out, the IR diode does something weird at start up (draws too much power, maybe?) and the entire ESP8266 hangs. I have to physically detatch the LED, boot the ESP8266 and then plug in the LED. That particular bug was not a lot of fun, and was only solved through an equal measure of google searches and dumb luck.

Once I got that working, I copied the original poster's simple web server, and made it even simpler, knocking it down to a single entry to toggle the power on my AC unit. Here's what the front end looks like, in its entirety:

Brian's ESP8266 IR Remote

FAN ON/OFF




Miraculously, it worked! And all I really needed is that link: http://192.168.1.194/ir?fan=power. A GET command to that link with cause the ESP8266 to issue the "toggle" IR command. Booyah!

Later on, I'll have to put this on a smart plug that can monitor energy usage, so I can know whether the unit is on or not, and decide to toggle the IR command or not. But that's for Step 2: Automation. For now, all I've done is add that toggle command to my Alexa HA Bridge (from BWS systems - it's the best Alexa HA bridge I've used so far)

Now that I've got this one working, I'll but together another one for the AC unit in the master bedroom, and then I'll integrate it with OpenHAB, and (hopefully) Nest. Making it work with Nest would be a real coup - I don't think anyone else has pulled that off yet, and I've got an idea for how to do it that I haven't ready about anywhere else. But that will be a post for another day, after some more parts arrive from Amazon.

Air Conditioning

We liked our new portable air conditioner so much, we got a second one:

Here's the story:

The HVAC pros we called in to get quotes for a replacement furnace (ours is 23 years into its 20 year expected lifespan) and brand new central air conditioning all had a similar ball park:

• The furnace would have to be replaced to install central air conditioning.
• Our house would need about 2.5 to 3 tons of air conditioning capacity.
• The job would cost $11,000, minimum.

Since the furnace was still running fine, we opted to get the new portable AC unit for the master bedroom, and see how much life we could squeeze out of the furnace. A little online shopping revealed the 13,500 BTU/hr Haier model to be the best bang for the buck right now. That prompted Brianna to ask me (since I'm the mechanical engineer and should know these things) what the difference between "tons" and "BTU/hr" was in air conditioning.

I had to look it up, and it's actually pretty interesting: "Ton" was a slang term that later became standardized. It turns out that one ton of ice melting over the course of one day (24 hours) will remove (absorb) almost exactly 12,000 BTU/hr (for all 24 hours). So "one ton" of air conditioning means a unit that can remove 12,000 BTU per hour.

Our new portable air conditioner is rated at 13,500 BTU/hr. We were practically halfway to the 2.5 tons required for our whole house!

So, we ordered a second one while the price was still good. It won't be quite as efficient or effective as a properly sized central air conditioner, but it ought to keep the house below 75F, and the two units cost less than $800 total - a twelfth the cost of a whole new installation. When the furnace gives up the ghost, we'll probably install central AC. But until then, we'll hang on to our money. Or spend it on other things. Probably we'll spend it on other things.

***

Once we had the second AC unit on order, we got rid of the old evaporative cooler in the great room, which really had not handled the winter well (tons of rust, and all my fault since I did a poor job of winterizing it).

I installed this one a little differently: I removed the castors and placed the unit on top of an old IKEA table we had kicking around. I had to cut off 4.5" from the table leg to get it the right height (Actually, cutting off 4.625" probably would have been better, but oh well).

This height adjustment prevents the surrounding furniture from blocking air flow, and allowed me to set up the air ducts as the minimum possible length, which did require me to do some cutting:

(That's the radon mitigation system outside the window, not a part of the new AC unit). I also had to "adjust" one of the connection brackets with my dremel (Thanks Dad!).

Finally, since this is a ground-level window, and it can no longer lock while the ducts are in place, I added a locking pin:

And the best part is: the times the AC units have to work the hardest are also the times we'll have the greatest amount of solar energy production! We get to cool the house without heating up the planet!

Update: Brianna had the good idea to put a filter on the air intake. I'm very glad we did!

Update 2: One AC unit on the main floor wasn't cutting it. I set up a price alert, and a week later we were able to snag a third unit (the second for the main floor) for the same price. It is set up the same was in the opposite corner of the house, near the kitchen. We've been able to come home to a 72-degree house on days that hit 95+ degrees!

Old Evaporative Cooler is Gone!

This morning Brianna and I removed the evaporative cooler (which came with the house) from the Great Room window!

I threw it up on craigslist in the free section and clearly described it as "extremely rusty", then left for the local fair.

Five hours later, we had 12 (12!) responses, and the first guy in line had come and picked it up. It's gone!

New "Portable" AC unit

Our old window AC isn't working all that well anymore. We ordered a new one, and it arrived this afternoon. This evening, we got it installed.

Here's the old set up, for reference:

And here's the new unit:

Looks pretty decent. The giant ducts on the back are a bit of a downside, though:

I'm tempted to cut them to a shorter length, but that seems too "permanent" some how.

Note to self: it's a Haier 13,500BTU HPND14XCP. $359+tax from Walmart.

Edit: wow, this thing works great! It was dropping the room temp a degree every 10 minutes, where the old one dropped about a degree an hour!

Lincoln did not approve of the change. He was very verbal about it.

Edit 2: Old AC is gone. Posted on Craigslist and had it picked up that afternoon. We got two summers of use out of it, but I'm glad to see it go, now that we have the new one:

Furnace and Air Conditioner Quotes

Our furnace is original to our house, and at 23-years-old is already past its expected life of 15-20 years.

Rather than waiting for the furnace to break and have to replace it in a hurry, Brianna is arranging quotes to replace the furnace with a new model, and to add central air conditioning (which we don't currently have).

We've only had the Costco-endorsed HVAC guy out so far. The upshot is: minimum $10,000 to install a new, low-end furnace and AC unit from this company. And it shoots up pretty fast from there.

New Dryer

We bought a new clothes dryer. It runs on natural gas.

The old dryer was electric. So why does the new one run on natural gas?

One of our long-term goals as a family is to have an electric car that charges from our solar panels (enabled by net-metering). But when we sized our solar panel system, the utility only let us install a system big enough to cover our current electricity consumption.

Part of the plan to fit an electric car into our existing electricity budget was to switch from an electric to a gas dryer. Natural gas is an extremely economical heating source in the US, and with the advances in hydraulically fracturing gas-bearing shale reservoirs, the price of natural gas in the US is going to stay very low for several decades.

So switching over to a natural gas dryer has been part of the plan for a while now, and me breaking the old dryer just pushed forward the schedule a couple of years.

(We don't have any plans to update the clothes washer for a while - it's a low-efficiency model, but those have a much better track record for actually cleaning cloth diapers than the high-efficiency models do).

Sunday evening we made a family trip to our local Sears Outlet, and purchased a nice Kenmore gas dryer for 45% off list price due to some scuffing.

Because of all the snow on the ground, it wasn't until wednesday that the plumbers were able to come out and install the new gas line for us.

It's the yellow flex line. The other two lines go to our water heater and furnace.

Everything is working nicely now!

(I put the old, broken dryer on the free section of craigslist, and had multiple people offer to come pick it up Monday evening. It was surprisingly easy to get rid of it.)

Fixing the Dryer

Our clothes dryer has been making a lot of noise while running lately. I took off the cover today to figure out what exactly the problem was, and whether I could fix it easily.

It turns out the front "slide bearings" had been almost entirely worn away. Here's a photo of the new bearings on the left, and the remains of the old bearings on the right.

I replaced the bearings, cleaned out a crap-load of lint, and in the process discovered that several other plastic pieces look like they're about to fail, as well. It'll cost around $100 to buy replacements online. Sigh.

But wait! Once I verified that this took care of the squealing noise, I put the dryer's frame back together. In the process, I had to adjust the dashboard a little. There was a spark. The dryer no longer turned on. Facepalm.

I checked the circuit breaker and all the electrical connections. Heck, I even did a conductivity test on every wire. I have no idea what could have caused a short. Everything checked out. Only explanation is that some internal component got fried. Based on the location of the spark, the most likely component to be "burnt out" is the timer, which would cost at least $100 to replace.

So I've got $100 worth of components ready to fail in the near future, and a $100 component to replace just in hopes of getting it running again. $200 (not to mention the $36 sunk cost of replacing the bearings) just to keep an old dryer around for a few more years.

I think it's time for a new dryer. Brianna is actually pretty pleased with the idea of getting a new appliance.

Residential Heat Recovery

Huh, this is a neat idea:

Hot Spot Energy has a product that sits between the compressor and the evaporator in an air conditioner or heat pump. It extracts some of the waste heat and uses it at the hot water tank or even a pool heater.

So: Taking something that's entirely a waste product, and doing something useful with it. Makes a lot of sense. I'll have to revisit this if we ever get around to installing ductless heat pumps in our house (after the solar panels are paid off).

Appliance Removal

We paid twenty bucks to get a refrigerator, a chest freezer and a lawnmower hauled away to be recycled.

The fridge and lawnmower came with the house. The lawnmower never worked. The fridge worked for a while, but had a refrigerant leak. The chest freezer was something we found on the sidewalk last year, but I'm pretty sure it had already lost its refrigerant - it never got cold, and I couldn't find any other problem.

Now they're all gone, and it feels like we have more space again! Now we park the stroller where the fridge used to be:

Worx Landroid - Lawnmower Drone

Man, how did I miss this?! Worx has an autonomous, battery-powered lawnmower, and initial reviews are pretty positive. The price has really come down, too: list price is only $1000.

Sigh. On the other hand, I don't have a $1000 lying around for something like this. Also, previous experience with robot vacuums was very disappointing after the first year.

Guess I'll just keep my eye on it.

Automatic Feeder for the Dog

Our dog Eva is (theoretically) on a diet following her last vet appointment. However, between me and Brianna, it's more common for Eva to get fed twice or not at all (the food dish is almost always empty, regardless of how often she's fed).

So, I used an Amazon gift card and ordered an automatic pet feeder.

The Amazon reviews assured me there was a port for an AC power adapter (the feeder is nominally battery powered) even though I would have to order the actual power adapter separately.

I was lied to.

So, I drilled a hole in the housing and wired in the power adapter myself. Works great!

Old Dishwasher is Gone

Just unloaded the old dishwasher on a nice college-age-looking couple.

Amazing how much more interest I got once I listed it on Craigslist for $0 rather than $20.

Amazon Echo - Ordered.

I posted about the Amazon Echo when it was announced back in November. I didn't order one then, but I speculated that it could be pretty cool for home automation. Well, today Amazon announced that the Echo integrated with the Wemo and Phillips Hue platforms, and someone else made a messy hack to control their Wink Hub via the Echo. Amazon is also working on releasing a public SDK that I have high hopes for.

The Echo supposedly retails for $200 for people without Amazon Prime memberships, though I have a hard time believing anyone actually paid $200 rather than sign up for a free Amazon Prime trial. Yesterday was the last day for Prime members to buy the Echo for $100 (it jumped to $150 today). Yesterday I still wasn't convinced I wanted to make the purchase, but I locked in the option for a 7 day period. Today the news broke about Wemo and Hue, and I decided to go for it.

I just bought a bunch of Zwave switches (post about that should be up in the next couple of weeks), though, so my fun money budget was pretty tight. So I signed up for an Amazon credit card, which came with a $70 Amazon credit sign-up bonus. I applied that sign up bonus to the $100 purchase price, and wound up paying $30 out-of-pocket for the Echo! It's hard to get a decent bluetooth speaker for $30, so I'm pretty happy with that deal.

Unfortunately, Amazon is waaaay backordered on the Echos. Mine isn't scheduled to ship until June or July. :-/

New Dishwasher

The dishwasher that came with the house has never been in great shape. Recently, the dish racks have gotten really bad: a lot of the bars are simply missing, and rust is showing through everywhere. I have patched the rubber coating on the metal racks twice, but it never lasts long. Replacing just the racks (nothing else!) would cost three. hundred. dollars.

Today, Brianna and I decided we were ready to just replace the dishwasher entirely. We packed Link up and went to our local Sears Outlet. They had four refurbished dishwashers that were within our price range and mostly had the features we wanted. We bought the fifth one, which was just a little outside our price range, but fit our dishes perfectly (we had brought a plate and bowl with us, to test - the sales guy said he had never seen that before). While we were checking out, Link had one of the biggest poops of his life thus far. We managed get Link's diaper changed and load the dishwasher (an Electrolux with a small dent in the front panel) into the back of Brianna's hatchback, then headed home.

Here's a shot of the old dishwasher:

In the course of detaching the old dishwasher, I discovered the sink drain has been leaking. (Ah, the joys of home-ownership. My Dad warned me, but there's a difference between knowing and experiencing).

***Update: the next day - Leak is fixed. Whoever installed the garbage disposal just mucked up a bit. Everything is water-tight now. Years of water damage on the cabinet floor though. I picked up a mold-testing kit from Home Depot - we'll see if anything comes up.***

The new dishwasher fits our plates much better than the old one: in the old one, the plates were constantly in danger of falling forward:

The new one also makes much better use of the vertical space:

Here's the final product!

The new, white dishwasher matches the rest of the kitchen much better than the old black one did. It's also a LOT quieter.

Range Hood

This has been a two-day project: I finally got that range hood installed. And it's only been five months since I bought the stupid thing!

The first time I attempted this project, I ran into a wall stud I was unwilling to cut (the left wall, in this photo):

It wasn't until I was messing around with Christmas lights that I realized the back of the house is not one continuous line: about three and a half feet of the wall behind the cabinets is actually exterior wall!

That realization, combined with the plan to have Thanksgiving dinner at our house (it's a small group this year, and that way Brianna stays close to our hospital) led to me installing the range hood this weekend.

Saturday was very good weather - forty five degrees Fahrenheit and sunny. So I installed the exterior vent first. Sunday, when I took this photo, was of course snowy, which made me glad I got this part out of the way early:

Yes, I still have to take down the masking tape.

Once that was done, I prepped the range hood and started work on running the ducting through the cabinets:

I had also trimmed down the top of the cabinets to keep the ducting low:

With Brianna's help, I got the range hood into place:

At this point, I made a mistake. I assembled the in-cabinet ducting, but forgot about the back-draft preventer, which I had left in another room. I had already cut the ducting to size without it, and had to spend quite a bit of time taking things apart and fixing them in order get the back-draft preventer in place. However, things did fit together (in terms of matching diameters) much better once that missing piece was in place.

After that fiasco, I got the electrical sorted out:

And then I cleaned up my mess and called it a night.

Today, I worked on the ducting on top of the cabinets. I made myself an L shape:

And then made all the connections above the cabinets.

In the process, I made a (very small) blood sacrifice to the gods of home improvement. I think that's actually the first one for this house! (Electrical shocks are a different matter)

Later on, and hopefully with some help, I'll get some crown molding on top of the cabinets, which will hide the ducting from sight completely. For now, the vent hood actually looks pretty decent, and is very functional:

...Darn - you can't see in this photo, but all the steam from the skillet on the front burner is going into the hood - and it was on the "low" setting!

Comparing the work I did this weekend to work I've seen someone like my Uncle Gary do is a little disheartening - my "carpentry skills" have a looooong way to go. Fortunately, I can call for advice - Thanks for taking my phone call, Uncle Gary!