From Oil to All-Electric: My 1950 Cape Cod Journey

Chapter 1: The House

In early 2022, I bought my first home. A 1950 Cape Cod in Lyme, Connecticut — a small coastal town where the Connecticut River meets Long Island Sound. It's one of the most beautiful places in New England, and from the moment I saw the property, I knew I wanted to be here.

The house came with charm. It also came with a 77%-efficient oil boiler on its last legs, two oil tanks (talk about standby losses), no air conditioning, and enough air leaks to make a building scientist weep. The apartment above the garage (700 square feet) was part of the deal. As a single guy buying his first home, every dollar mattered — and energy was one of the biggest controllable expenses.

Which is exactly why energy efficiency wasn't just a professional interest for me. I'm a Certified Energy Manager. I own a consulting firm where energy is one of our core practice areas. I advise other people on this stuff for a living. But up until now, it was always someone else's building. This time, it was personal.

My electromechanical foundation came from the Connecticut vocational system, where my instructor Bill Campbell taught me how things actually work — pipes, pumps, motors, controls. The hardest lesson he drilled into us: practical exams were either a zero or a hundred. It either works or it doesn't. There's no partial credit when you're wiring a motor or sweating a pipe. That mindset stuck with me. The finance side came later at Fordham. This project is where both halves finally came together.

I figured it was time to put my money where my mouth is. Some people have started calling me "Decarb Devin." I'm a CT Yankee — I'll take it.

An EUI (Energy Use Intensity) of 95 kBTU per square foot per year put my home in the bottom 25% of Connecticut homes. For context, the average CT home sits around 45-55. Energy Star new construction is 30-40. I was nearly double the state average.

But I also knew something most people don't: a bad EUI isn't a death sentence. It's a to-do list.

The Jargon Decoder

Before we go further, here's a quick cheat sheet. I'll try to keep things in plain English, but some technical terms are unavoidable. Refer back to this anytime:

Chapter 2: Measuring the Problem

Before I spent a dollar on improvements, I wanted to understand exactly what I was dealing with. Energy audits are great, but I wanted continuous data. So I did two things.

First, I got a home energy audit through Energize CT, Connecticut's energy efficiency program. If you're in CT and haven't done this yet, do it — it's heavily subsidized and it's the single best first step you can take. The audit confirmed the obvious: the envelope was the biggest problem. Air leaks, insufficient insulation, and ducts that were basically heating the inside of my walls.

Now here's the thing — the auditor didn't actually recommend the heat pump or any specific mechanical system. That research I did on my own. What the audit did was quantify the envelope problems and estimate I could cut 19 kBTU off my EUI just by addressing insulation and duct sealing. That was enough to get me started.

Second, I installed a Smart Oil Gauge on my oil tank. It's made by a Connecticut company, and it tracks your fuel level every hour using an ultrasonic sensor. For six weeks over the coldest stretch of winter — December 27, 2022, through February 5, 2023 — I had a complete record of exactly how much oil my house was burning and at what outdoor temperatures.

The data told a clear story. On a typical winter day (30-40°F), the house was burning 4-5 gallons of oil. On cold days (20-30°F), it climbed to 5-6 gallons. And on the coldest day of the season — February 4th, 2023, when the average temperature hit 5.5°F with a low of -7.5°F — the house burned 10.6 gallons.

At 77% boiler efficiency, 10.6 gallons per day translates to roughly 60,000 BTU/hr of input, delivering about 46,000 BTU/hr to the house. But that was just the main house — and it was before insulation. I knew the envelope upgrades would significantly reduce the main house load. So I factored in the apartment above the garage, which I planned to heat from the same system as a central plant. The reduced main house load plus the added apartment and garage square footage brought me right back to needing about 60,000 BTU/hr of capacity. That became my sizing target. (I still need to commission the air handling unit in the apartment and garage — there's more performance to unlock once those zones are fully online. The garage will only need heat occasionally — mostly when I'm out there tinkering on my automated trash can. More to come on that one.)

Chapter 3: Fixing the Envelope

The cheapest BTU is the one you don't need. Before installing any new heating system, I needed to reduce the load. In 2023, I tackled the envelope:

• Wall insulation — blown-in cellulose into the existing wall cavities
• Attic insulation — brought up to current code levels
• Duct work — cleaned, wrapped with insulation, and aerosealed (August 2023)

Aerosealing is worth calling out specifically. It's a process where a machine pressurizes your duct system and injects sealant particles that collect at the leak points. My ducts were losing a significant amount of conditioned air into unconditioned spaces. After aerosealing, the system was delivering heat where it was supposed to go.

The results were measurable immediately. My EUI dropped from 95 to 56 — a 41% reduction just from tightening up the building.

"Fix the envelope first, then size the equipment. The insulation alone cut 35% off my heating cost before I even touched the mechanical system."

This also had a secondary benefit: a lower heating load on the main house meant the heat pump I was planning could take on additional zones without being oversized for any single one.

Chapter 4: Why Air-to-Water (and Not Geothermal)

With the envelope done, it was time to replace the dying oil boiler. I spent months researching the options. As a CEM, I knew the landscape: conventional air-source mini splits, air-to-water heat pumps, and geothermal (ground-source).

The Geothermal Question

Everyone I talked to said the same thing: go geothermal. Best COP, they said. And they're right — ground-source systems achieve COP of 4.0-5.0 because the earth stays at a constant ~50°F year-round. No matter how cold it gets outside, your heat source is always 50 degrees.

But there's a catch nobody mentions until you get the quote: the well drilling. For my property, a geothermal system would have required $20,000-$40,000 just for the ground loop — vertical wells drilled 200-300 feet deep, or horizontal trenches across the yard. Total installed cost: $30,000-$50,000. As a first-time homeowner on a single income, the payback math simply didn't work.

Discovering Air-to-Water

Then I found something interesting. Air-to-water heat pumps — standard equipment across Europe, but nearly unknown in the US residential market. I'd actually seen these units everywhere in Germany, especially around Munich (one of my favorite places). They're on the side of every house over there. The Germans have been heating with these things for decades — the home of some of the greatest engineers in history — including Rudolf Diesel, the inventor of the diesel engine. (If you haven't read about him, there's a fascinating book on Amazon: The Mysterious Case of Rudolf Diesel. The guy invented one of the most efficient combustion engines ever made, and his story is wild. A real favorite of mine right now.) Anyhow, I digress. It's not experimental technology, it's just technology that hasn't crossed the Atlantic yet. The concept is simple: extract heat from outdoor air, just like a mini split, but deliver it as hot water instead of forced air. Hot water means hydronic distribution: fan coils, radiators, in-floor heat, and — crucially — snowmelt. All from one system.

The key insight that changed my mind: modern air-to-water systems achieve COP of 3.0-4.5+ in cold climates. That's 80-90% of geothermal performance at roughly half the installation cost. No wells, no drilling, no loop field, no yard disruption.

"Everyone told me to go geothermal for the best COP. But air-to-water got me 80% of the way there at half the price — and I could do snowmelt, which geo would have needed a separate loop for."

Chapter 5: Building It

Finding the Apollo from MBTek

I found the Apollo 5T through MBTek, one of the few distributors bringing air-to-water equipment into the US residential market. The Apollo checked every box:

• Rated COP of 3.6-4.8 depending on conditions — competitive with geothermal
• Designed for cold climates (rated down to -4°F)
• Hot water output up to 170°F — enough for existing hydronic distribution
• ~60,000 BTU capacity — a precise match for my measured peak load
• One system for heating, cooling, domestic hot water, AND walkway snowmelt

The sizing math was straightforward. The Smart Oil Gauge had measured a peak load of ~60,000 BTU/hr before insulation. After the envelope work, the main house load was significantly reduced. Adding the 700 sq ft apartment to the same system (central plant concept), the Apollo 5T at 60,000 BTU/hr was the right size to serve the entire property.

The Six-Month Wait

I ordered the outdoor unit, the indoor Hydro Smart pumping station, a buffer tank, and the DHW tank. Then I waited. And waited. The unit took about six months to arrive — this was still a niche product in the US supply chain.

While I waited, I ordered all the supporting materials — piping, fittings, valves, controls, everything needed to hook it all up — from SupplyHouse.com. And I dry-fitted the entire system in my garage before any of the major equipment arrived. Every pipe run mapped out, every connection accounted for. Bill Campbell's voice in my head: it either works or it doesn't.

We Make Plans and God Laughs

Of course, not everything went exactly as drawn up. The MBTek 5-ton air handling unit, for example — the stock motor was so loud I couldn't stand it. In a house this quiet (no combustion equipment, no oil burner rumbling away), every decibel stands out. I ended up ripping the guts out of the AHU and replacing it with an ECM motor. Not my favorite project, but the noise was killing me. The lesson: when your house gets really efficient and really quiet, your tolerance for mechanical noise drops to zero.

But having the dry fit done meant I could adapt when things didn't line up, instead of figuring it out on the fly with the clock running. I did the general labor myself. I've also installed BTU meters throughout the system — haven't hooked them all up yet, but when I do, I'll be able to measure performance on every zone independently. More data to come.

Chapter 6: The Install

On November 15, 2023, the oil boiler came out and the Apollo 5T went in. The system was built out in stages — the initial install included the outdoor unit, Hydro Smart Station air handler (three zone circuits), 30-gallon destratification tank, DHW tank, and all piping. I added the 80-gallon Lochinvar buffer tank in March 2026 (~$3,400) after the data showed short cycling was leaving performance on the table. Total cost all-in: $35,000, including every component and all labor.

But here's the thing most people miss in the cost analysis: the oil boiler was at end of life. I was going to spend $8,000-$12,000 on a new heating system regardless. And there was a 30% federal tax credit on the heat pump installation. So the real math looked like this:

A 14.4% annual return, guaranteed and inflation-protected. Better than the stock market average, and unlike stocks, this ROI heats my house, cools it, and melts my walkways.

The system serves the entire property from one outdoor unit: three heating zones through the air handler, cooling in summer, domestic hot water, and a snowmelt loop for the refurbished walkways. In the summer, the DHW performance is excellent — essentially free hot water as a byproduct of the system. And there's still capacity for more zones if I ever want to expand.

My neighbors think I have a heated driveway service. Nope — just a heat pump and some walkways I rebuilt.

Chapter 7: The $50 BTU Meter

A commercial BTU meter — the kind you'd use to verify system performance — costs about $1,500. I built one for fifty dollars.

• ESP32 dev board + screw terminal breakout~$12
• 2x DS18B20 waterproof temperature sensors~$6
• 4.7kΩ resistor (OneWire pullup)~free
• GREDIA G1 brass flow meter (pulse output)~$30
• Wire, cat5 cable, 5V power supply~$6
• Total~$50

The ESP32 reads supply and return water temperatures, counts flow meter pulses to calculate GPM, and computes BTU output in real time. An Emporia Vue energy monitor on the heat pump circuit measures electrical input. A custom Node.js server on a DigitalOcean VPS calculates COP (BTU output divided by electrical input) and serves everything to a live public dashboard.

I also added a Resideo/Honeywell integration for indoor zone temperatures, and a weather bridge that pulls outdoor conditions from the National Weather Service API every ten minutes.

Yes, I built a SCADA system for my house. Not many people have this level of commitment to actually proving their system works. But that's exactly what separates guessing from knowing. And as you're about to see, it caught something that would have fooled almost anyone.

The live dashboard is public: tools.schleidtworks.com/honeyhilllane/simple.html

Chapter 8: The Plot Twist

For weeks after building the monitoring system, my dashboard was showing a COP of 1.2 to 1.9. For a system rated at 3.5-4.5, that's terrible. I was losing sleep over it. I was convinced the 15kW backup electric heater in the air handler was firing constantly, destroying my efficiency. I was ready to call the installer and tell him something was seriously wrong.

Then I found it.

The Emporia Vue channel multiplier was set to 2x when it shouldn't have been. The Emporia's instructions for 240V circuits are confusing — I thought I needed to set the multiplier to 2, but the current transformer was already reading both legs of the 240V circuit. Every single kilowatt reading was doubled. My COP wasn't 1.5. It was 3.0-3.8 the entire time.

The backup heater wasn't firing. There was never a problem. The system I built — the ESP32 meter, the flow sensors, the temperature probes — was reading correctly the whole time. The one thing I didn't build (the Emporia configuration) was the thing that was wrong.

This is the part of the story that I think matters most. If I hadn't built the monitoring system, I never would have caught this. But more importantly: if I hadn't built it, I also never would have known my system was working well. I might have lived with a "bad" heat pump for years. I might have ripped it out and gone back to oil, convinced the technology didn't work in my climate.

How many people are out there right now with a perfectly good heat pump, thinking it's broken because of a monitoring error they don't even know about?

"Measure everything. But verify your measurements, too."

Chapter 9: Tuning

With accurate data finally in hand (March 2026), I turned to optimization. Three changes made a measurable, verifiable difference.

ECO Mode (Weather Compensation)

The Apollo has an outdoor reset feature called ECO mode. Instead of always targeting the same water temperature setpoint, it adjusts based on outdoor conditions. When it's 45°F outside and you only need 100°F water, why heat to 130°F? Lower water temperatures mean less temperature lift for the compressor, which means higher COP. It's called outdoor reset because it resets the target water temperature based on outdoor air — tightening the relationship between what the house needs and what the compressor delivers. Less waste, more efficiency.

Before ECO mode, I was running a fixed water temperature of 110°F for heating. That works, but it's overkill on mild days. With outdoor reset enabled, the system performs a regression analysis — as outdoor temps rise, the target water temp drops. On a 45°F day, it might only heat to 95°F instead of 110°F. That lower water temperature means the compressor runs at a lower lift, which directly improves COP. It's the same principle as driving your car at 55 mph instead of 80 — the engine works less hard for the same trip.

This is standard practice in European hydronic systems. In the US, most installers leave it off because it requires understanding the building's heat loss curve. With my BTU meter, I could see the impact immediately.

Buffer Tank Optimization

The system has 110 gallons of thermal storage: an 80-gallon Lochinvar buffer tank and a 30-gallon destratification tank. Without a buffer, here's what happens: a zone calls for heat, the compressor fires up, the water gets hot quickly (because the loop volume is small), the thermostat satisfies, and the compressor shuts down. Two minutes later, the temp drops and it fires again. That's short cycling — and it's the enemy of efficiency. Every startup wastes energy, wears the compressor, and prevents the system from reaching its optimal operating point.

The buffer tank solves this by giving the compressor a large thermal mass to heat. Instead of cycling on and off every few minutes, it runs for 30-60 minutes at a time, building up stored heat in the 110 gallons. The zones pull from the buffer as needed. When the buffer cools below the setpoint, the compressor kicks back on for another long, efficient run. I dialed in the aquastat on the destrat tank (111°F setpoint, 9°F start differential, 3.6°F stop) to keep the buffer properly charged without overshooting.

The buffer also delivers heat to the zones even when the compressor is off — heat that my primary-loop BTU meter doesn't directly capture. My COP calculation includes an idle-hour correction to account for this stored heat delivery, which adds about 24% to the measured BTU output on average.

Backup Heater: Disabled

The Hydro Smart air handler has a 15kW electric resistance backup element. After confirming it was never actually needed (the Emporia error had made it look like it was), I disabled it at the outdoor controller. Rest in peace.

The combined effect: kWh per heating degree day dropped from 2.15 to 1.73 — a 20% improvement. The best week hit 1.44 kWh/HDD. And the air handler backup element went from pulling 7-12 kWh/day in early March to essentially zero. That's not a projection — it's showing up in the Emporia data.

Chapter 10: The Numbers

Everything in this section is measured, not modeled. The COP values come from my BTU meter and Emporia circuit monitor. The costs use actual utility rates. The weather normalization uses actual HDD data from the Open-Meteo API for Lyme, CT.

COP by Outdoor Temperature

Lifetime average: 3.64 COP over 450+ compressor-kWh tracked. At the Apollo's rated conditions (41°F outdoor, 95-131°F water), the manual claims COP 4.8. I'm measuring 3.5-4.5 in that range, which is realistic after accounting for real-world piping losses and part-load operation.

Weather-Normalized Heating Cost

To compare costs fairly across years with different weather, everything is normalized to a standard 5,500 HDD year (typical for Lyme, CT). This eliminates the "it was a mild winter" variable.

* Heat pump numbers include space heating, domestic hot water, walkway snowmelt, and system overhead (circulator pumps, controls). The oil numbers include space heating only — DHW was a separate electric resistance heater (not included in oil cost). The heat pump replaced both the oil boiler and the electric resistance water heater with a single system, so a direct $/HDD comparison understates the HP's value.

Actual HDD by Year

For context, here's how each year's weather compared to normal:

The oil years (2022-2023) were mild winters, meaning my actual oil costs were lower than they would have been in a typical year. The savings from electrification are actually understated when comparing to those mild-winter oil bills. Weather normalization corrects for this.

Chapter 11: Where I Stand

EUI measures total site energy per square foot per year. It's the single best number for comparing buildings. Here's where a 1950 Cape Cod sits after three years of work:

Most homes at EUI 21 were specifically designed and built to be there — new construction with triple-pane windows, 12-inch insulated walls, HRV ventilation systems. Mine got there through staged, practical improvements to a 75-year-old house. No teardown required. No six-figure renovation. Just data, a plan, and patience.

Chapter 12: The All-Electric Life

In December 2024, I added a Tesla Model S. At that point, everything in my life ran on one fuel: electricity. Heating, cooling, snowmelt, and 20,000 miles a year of driving. One bill, one fuel source, no combustion anywhere on the property.

Yes, my electric consumption tripled from 2022 to 2025. That looks alarming until you realize what it replaced: $3,600+ per year in oil deliveries, $400 in window AC units I didn't have, and $2,268 in gasoline. The heat pump delivers 3.6 units of heat for every unit of electricity, so tripling electricity while eliminating combustion fuels is exactly the math working as intended.

* All costs based on March 2026 pricing: $0.26/kWh (Eversource CT), $4.94/gal heating oil, $3.40/gal gasoline. Weather-normalized to 5,500 HDD.

Budget Billing: The Hidden Advantage

Here's something most people don't consider: I'm on my utility's budget billing plan. It spreads my annual electric cost into twelve equal monthly payments. In January, when consumption peaks, I'm effectively borrowing against my low summer months — at 0% interest.

With oil, you pay market price on delivery day. A $1,500 fill in January hits all at once, and oil prices can swing 30-40% in a single season based on global markets. Budget billing on an all-electric home is effectively a fixed-rate energy plan. Predictable, stable, no surprises.

And if you think about it from a time value of money perspective — my Fordham finance professor George would be proud — I'm essentially getting an interest-free loan from the utility every winter. I'm consuming more than I'm paying for in December, January, February, and paying it back with my lower summer usage. That's free financing on my biggest expense months. Try getting 0% APR on an oil delivery.

"I heat my house, cool it, make my hot water, melt my walkways, and drive 20,000 miles a year — all for about $370 a month. On one electric bill. No oil deliveries, no gas stations, no combustion."

Chapter 13: The Full Timeline

Chapter 14: What I Learned

Fix the envelope first. Insulation and duct sealing alone cut 35% off my heating cost. This is the highest-ROI work you can do, and it benefits you regardless of what heating system you use.

Measure before you buy. The Smart Oil Gauge told me exactly what size system I needed. No guesswork, no oversizing, no undersizing. Six weeks of data was worth more than any contractor's rule of thumb.

Air-to-water is the sweet spot. For cold climates where geothermal is too expensive and mini splits can't do hydronic distribution, ATW heat pumps deliver 80% of geo performance at half the cost — with cooling and snowmelt included.

Measure after you buy, too. My $50 BTU meter caught a monitoring error that would have had most people convinced their heat pump was broken. The system was working perfectly; the measurement was wrong.

Tune the system. ECO mode, buffer tank optimization, and disabling the backup heater delivered a 20% efficiency improvement that most installers never bother with. The equipment is only as good as its configuration.

A 1950 house can perform like a 2024 house. You don't need to tear it down and start over. You need data, a plan, and the patience to do it in stages. EUI 95 to EUI 21 in three years, on a real-world budget.

A Personal Note

I'm just a single guy who bought his first home in a beautiful place and wanted it to be the best version of itself. Making this home efficient, healthy, and clean — that's my hobby. It's what I work on in the evenings and weekends. It's my serenity.

If you're thinking about doing something similar, I hope this gives you a roadmap. Every number on this page is real. The dashboard is live. And if a 1950 Cape Cod in Connecticut can get to the top 10%, your house can too.

If You Want to Do This

Here's the approach I'd recommend, in order:

1. Get an energy audit. Know what you're working with. In Connecticut, go through Energize CT — it's heavily subsidized. The audit won't tell you everything (mine didn't suggest the heat pump), but it will quantify your envelope problems and that's where you start.
2. Install a Smart Oil Gauge (or equivalent). Track your actual consumption for at least one cold month. You need your real heating load, not a guess.
3. Fix the envelope first. Insulation, air sealing, duct sealing. This is the best money you'll spend.
4. Size the heat pump from data. Use your measured load (adjusted for the improved envelope) to pick the right equipment. Don't oversize.
5. Consider air-to-water if you want hydronic distribution, DHW, snowmelt, or a central plant serving multiple zones. Look into MBTek for the Apollo units, and SupplyHouse.com for all the piping, fittings, and supporting materials.
6. Apply for incentives. Federal tax credit (30%), state rebates if available, utility programs.
7. Monitor the system. Even if you don't build a $50 BTU meter, at least put a circuit-level energy monitor on the heat pump. Verify it's performing.
8. Tune it. Enable weather compensation. Optimize your buffer tank. Don't leave performance on the table.