We turned off our natural gas meter this month, and we just paid our final bill with the gas company!
All major systems in our house are fully electrified, and we have a high-efficiency wood-burning stove as an additional heat source!
We still have a number of effficiency gains we can make, but it feels good to savor this accomplishment :-)
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.
As part of our on-going electrification efforts, we replaced our natural-gas powered clothes dryer with an electrically powered heat-pump clothes dryer. This also entailed the final bit of new flooring installation, as I only wanted to move these appliances once.
First up was removing the washer and dryer, and removing and capping-off the natural gas line that went to the dryer:
Then came laying down the last bit of LVP and patching the vent hole:
Here's what happened on the outside of the house:
The heat pump is doing great! You can see on the left side of this photo that we got down to -13°F this morning, but we still haven't seen the emergency resistive heater kick on. Looks like all the insulation upgrades and new windows are paying off and we have a fairly resilient system!
We replaced our 2005 Ford Freestar minivan with a 2021 Chrysler Pacifica Hybrid minivan!
We were starting to get a little worried about the reliability of our old minivan, and we were looking at options for a new people-mover. We were hoping to get an all-electric car, but there just aren't any minivan equivalents available yet in an all-battery option. The closest thing we could find was the plug-in hybrid Pacifica.
The battery on the Pacifica is small enough that it can easily charge over night on a 120 volt, 15 amp plug. But I'm hoping to upgrade the electrical in the garage soon, so we can have two 240 volt EV chargers in there.
Well, my electrician fell down while hiking and broke his collar bone two days before he was due to come out an do the final electrical installation on our heat pump.
Amazingly, he was amazing enough to drive over anyway (with a broken collar bone! on his way to the doctor!!) and walk me through what needed to be done. I then proceeded to do it.
I added a new 2" conduit for the cables for the heat pump and the emergency resistive heater:
(Oh: the electrician tried to refuse payment since he "didn't install anything", but I was able to give him something for his trouble. Happy to recommend someone with that much work ethic!)
Since we started thinking about replacing our old natural-gas furnace with the geothermal heat pump, we have really been thinking about where the heat leaks in and out of the house. We have 17 aluminum frame windows in the house still (a previous owner installed vinyl windows in the bedrooms and all the south-facing windows), and some of these old window frames have noticeable gaps allowing air to just flow through. So we replaced 10 of the aluminum frame windows (the ones on the first floor) over the course of this year with energy-star vinyl windows. That should tighten up the bulding envelope considerably, and make it more likely we can get through the coldest days of winter without having to use the backup electric resistive heater.
Man, I wish we had done the windows before we had the painters replace so much of the window trim last year. Live and learn, I suppose.
EDIT 2/1/2022. We've had a number of days in the single digits (F) since installing these windows. The old windows would actually ice over with frozen condensation when we got down to about 15 degrees F. The new ones just feel mildly cold. We are really pleased with how much better the new windows are.
We finally heard back from our electric utility about upgrading our grid-tie connection. Months ago, they assured me it would be around $1,000, with a 4 week lead time.
They now want $8,000, with no firm time frame.
And that's not counting roughly $6,000 our electrician estimated for a new meter and upgraded electrical panel.
...
I'm not f---ing doing it.
I've been going over the form the National Electric Code issues for load-sizing a house. You do get some derates by assuming you don't actually have every single light on in the house at the same time, but even that assumes you have inefficient incandescent bulbs (we're fully LED now) and also assumes you have everything else on at once: the electric oven, the heat pump, the backup electric resistive heater, the car chargers we threw in there when we were thinking we would have 400 amps of capacity to play with...
It turns out, as long as we don't run the electric resistive heat and the oven at the same time, we fit in our 150 amp budget. Or if we turn off the car chargers (which we don't even have yet), we can run the oven and the resistive heat together. If any one of those three things doesn't run, we can have everything else in the house sucking down as much power as possible, and still fit in the 150 amp budget.
Why don't they tell people that kind of thing? We could have had the heat pump electrical done on the same day as the rest of the install if we had known that.
Ugh.
So how do I automate this so I don't accidentally trip my main circuit breaker in the future, when we have fully electrified the house and have two electric cars?
There's a company selling a "smart" circuit breaker panel called Span, which seems to be exactly what I want. It can turn loads on and off at the circuit breaker level to keep the total load under a set threshold. I sent them a request for quote, but haven't heard anything back in 8 weeks now.
In the mean time, I've been using an Emporia Vue energy meter for about a year now. It clamps on to the main cables from the grid and up to16 individual circuits inside the panel, reporting through wifi to a smartphone app.
In the meantime, we are now on the electrian's schedule to get final wiring in place, followed by final inspection by the city. Hopefully we'll have this project buttoned up soon.
We still don't have a date for our electrical utility upgrade (from 150amps to 400amps), but I've been repeatedly told it should be about $1000. The HVAC contractor is getting antsy, and has had our equipment purchased and sitting around their shop for a couple of months now, so we are going ahead with the heat pump installation. Apparently we can run temporary electrical to test it out, and do final electrical (and inspection) later. Hopefully it all goes as planned.
The HVAC contractor showed up on monday. They're scheduled to be here for four days, but are hoping to knock it out in three.
We got a Energy Recovery Ventilator (ERV) installed as part of this project. We are hoping to continue tightening up the building evelope, especially as we eliminate the need for combustion air for natural gas appliances, and the ERV will ensure we still get enough fresh air.
And finally, we have a steam humifier for the dry winters here in Colorado:
UPDATE October 2021: The steam humidifier does a great job keeping the humidity up, but it's an absolute energy hog. In the autumn, the steam humidifier is often using more electricity than the entire heat pump. I'm a little horrified to think how much power it's going to use in the winter. I'm actively looking into different solutions for humidity now.
Phew, the wells for the geothermal ground-loops are drilled, the ground-loops themselves are installed, pressure-tested, and grouted in place for eternity, and the pump (not heat-pump) is installed in our basement.
The drilling was done by Colorado Geothermal Drilling, and we are happy to recommend them.
The drilling equipment started showing up on Wednesday, and we dismantled the fence to our backyard.
The Drilling Rig was actually a custom job mounted on a skid-steer. Pretty much the only way we could have fit a drilling rig onto our property, as it turned out.
Sigh. I was able to do a temporary repair of the internet line so Brianna and I could continue to work from home, and the kids could continue to watch Disney Plus, but I'm not really sure how much longer that cable will last.
And here's where the pipes enter the house, and what the ground-loop pump looks like inside the house:
