Geothermal Check-in - Winter

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! 

Geothemal - Electrical

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:

And each circuit (60 amps) has a disconnect point anchored to the wall:

Speaking of the emergency resistive heat, here's what the heater looks like:

It's so tiny compared to the whole heat pump!

I spent around $400 on materials, mostly on the wire. And it passed inspection and has been working great! I'm so happy we didn't spend the $14,000 on upgrading the electrical grid connection.

(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!)

Geothermal - Update on Electrical and the Emporia Energy Monitor

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.

And Emporia has come out with an EV charger that can adjust to keep peak load below a set threshold, and they're saying they are working on individual smart circuit breakers, thermostats, and "smart appliances" (which I hope means electric water heaters).

If Emporia is for real, I might be able to completely solve this problem for a few hundred dollars, rather than fourteen thousand dollars.

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.

Geothermal - Heat Pump and Ducting install

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.

They immediately got to work dismantling and removing our old natural gas furnace.

By the second day, they had the heat pump in place!

Here are some photos of the guts of the heat pump:

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.

Geothermal - Wells

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.

The plan was to drill down to 300 feet three times, with the wells spaced twenty feet apart. This gives us 900 linear feet of vertical well, which exceeds the 200 feet per ton of heat pump capacity (we are going to have a 4-ton heat pump) rule of thumb used in Colorado. It turns out they drilled the well closest to the house 300 feet deep, moved over 20 feet and drilled the next well 280 feet deep, moved over another 20 feet and drilled the last well 260 feet. It still adds up to 900 linear feet, but I would have preferred we got the full 300 feet on each well. 

The driller hit substantial ground water about 70 feet below ground. That's great in the long-term, as it means our ground loops should have really good thermal conductivity to the surrounding earth. In the short-term, though, the extra water that came up while drilling meant an extra $3,000 in water disposal fees. These two temporary tanks lived in our driveway this week, and vacuum trucks came and emptied them several times as the water kept coming up.

After drilling each well, they ran HDPE pipe down hole. It came in these big reels:

Once the wells were drilled and the vertical pipe installed, tested, and grouted in place, the drilling crew used an excavator to dig a four-foot-deep trench to connect the wells to the house.

Of course, unknown to anyone, two of our lawn sprinkler lines AND OUR INTERNET CABLE crossed where the trench would be dug.

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:

Those lines on the floor will be connected to the heat pump when it's installed. The lines are filled with a water/methanol mix. We still haven't gotten word from the electric utility about when they can upgrade our electrical service, so we have had to push off the actual heat pump instalation until June (hopefully).

Our front and back yards are completely trashed - we have no grass left. We were warned, but I don't think we really quite understood. We also have this giant pile of sand that came up from drilling through sandstone:

And one of our sprinkler boxes got smashed and the valve solenoids broke off.

Still, we are very happy to be making progress on this project, and thrilled we were able to get on the driller's schedule this quickly.

Going Geothermal

The furnace in our house is 28 years old (original to the house), and it is, frankly, on its last legs. Rather then trying to coax it through a few more years and risk it dying on the coldest day of winter, we are going to take advantage of the current federal tax credit and install a geothermal heat pump (also called a ground-source heat pump).

The great thing about heat pump is they can operate in reverse: heating in the winter, and cooling in the summer, with no additional equipment required. Our house will finally have Central AC!

(Source: https://www.epa.gov/rhc/geothermal-heating-and-cooling-technologies)

We spent a lot of time researching and looking for qualified installers. Given the limited space on our lot, we're going to have to go with vertical ground-loops (the other option being long trenches of horizontal ground-loops), but hopefully that won't destroy our landscaping too badly, compared to trenches.

It wasn't particularly easy to find good installers here in Colorado (one HVAC salesperson was planning to bring a driller in from FLORIDA for the ground loop), but we should break ground on the vertical wells in April. One hang-up is that we're going to have to upgrade our electrical utility connection from the measly 150 amps we have now to a 400 amps service. Good new is, that will allow us to fully electrify and get off natural gas entirely, as well as shift over from gasoline to electric vehicles.