Watch: the walkthrough
Sound's on — this is a walk through St. Teresa's, from the street up to the sanctuary and down into the stone basement, talking through what I'm seeing and what I'd do about the comfort problem.
What I walked into
The church sits at 162 North Main Street in Port Deposit, Maryland, and the first thing you notice is that there's barely room for it. The whole town is built on a thin ribbon of flat ground squeezed between the Susquehanna River on one side and a steep granite escarpment — in places an honest cliff — on the other. (Maryland Historical Trust.) The building is gray stone, with tall arched stained-glass windows, a little bell cote up top, a cross on the gable, and a slate roof. It's built right into the hillside, so the lower level reads almost like a stone basement coming out of the rock.
The sign in the lot says St. Teresa's Church. The folks I was there for call it Church of the Good Shepherd. Both are right, and it's worth untangling, because I almost got it wrong myself.
Two names, one church
Here's the honest version, straight from the Diocese of Wilmington's own records. The congregation in this building is St. Teresa of Avila. Catholic ministry in Port Deposit goes back to 1857 as a mission, and the congregation was formally named in 1866. (Diocese of Wilmington 2026 parish directory.)
Church of the Good Shepherd is the parent parish — it's actually headquartered a few miles away in Perryville, and it was established in 1949. When that happened, St. Teresa's became one of its mission churches. (Iron Hill Deanery Pastoral Plan.) So the parking sign and the parish name aren't a contradiction — they're just two levels of the same Roman Catholic family, in the Diocese of Wilmington. It's still active today, with one Sunday Mass and a congregation of around 45 to 50 people. (Diocese directory.)
One honest caveat: I couldn't pin down the exact year the stone building itself was put up. The mission dates to 1857 and the congregation was named in 1866, and Port Deposit's historic district runs from 1812 to about 1910 with most of it built between the 1830s and 1890s — so a stone church here from the late 1860s to 1880s is reasonable, but I'm not going to hand you a date I can't source. (Maryland Historical Trust.)
The town is the reason it's stone
You can't tell this church's story without telling the town's. Port Deposit sits on top of one of the most famous building stones in the country — Port Deposit granite, which geologists will tell you is technically a gneiss, a bluish-gray metamorphic rock flecked with black mica. (Port Deposit Gneiss.) They quarried it right out of the bluffs above town from about the 1830s through the turn of the century, and it ended up in some serious places: the U.S. Naval Academy, Fort McHenry, the Boston Public Library, the U.S. Treasury Building. (same source.) When your town is sitting on stone like that, you build with stone — houses, retaining walls, and five churches in Port Deposit alone. St. Teresa's is almost certainly one of them.
The other reason for all that stone: the river tried to destroy this town on a regular basis. Every few winters the Susquehanna would freeze solid, then break up in a warm spell and send walls of ice tearing downstream, jamming up and backing water into town in minutes. The 1904 Great Ice Flood destroyed or wrecked dozens of homes here. (Uncharted Lancaster; USGS.) That's why so many buildings sit up on high stone basements and granite retaining walls — it's survival architecture. A church built up into the granite hillside gained a little elevation above the water and made use of the only flat ground there was. The whole town has been on the National Register of Historic Places as a historic district since 1978.
And here's a detail I didn't expect to love as much as I did. Out back, tucked into the narrow gap between the church wall and the rock, the original natural spring still bubbles up out of the ground — the same water that's fed this place for generations. There's even a hose set into the channel to carry the overflow off so it doesn't undercut the foundation. A stone church on a cliff, watered by its own spring. You don't see that twice in a career.
They built this church out of the same stone as Fort McHenry, up on a cliff, to outlast a river that kept trying to wipe the town off the map. A hundred-plus years later, it's still standing, still watered by its own spring — and somebody still has to keep it comfortable on a Sunday morning.
Now the part I can't turn off — and it's two separate systems
This is where my brain takes over, because this is what I do. And the first thing to be clear about: the heating and the cooling here are two completely separate systems. The furnace does not feed the air conditioning, and the air conditioning does not touch the furnace. They live in two different parts of the building and they work independently. That matters for how you plan the job.
Start in the basement — a real stone basement, not a crawlspace. The foundation is massive cut-stone piers — the same gneiss as the walls — with wood joists overhead. The heat comes from a Williamson furnace (that one's badged clearly on the cabinet), and it's newer — the cleanest piece of equipment in the building, sitting down in the stone with a galvanized supply plenum off the top of it. The electrical tells the whole history of the place: a Square D QO panel with a hand-written, coffee-stained directory where somebody penciled in “ORGAN,” “Meeting Rm Lights,” and “FURNACE” — that last one traced over twice in red marker, the way you do when you're tired of looking for the right breaker.
Now the cooling — that's the old iron. The exterior condenser is the headliner. It's a split-system unit, and the nameplate doesn't lie: built 6/1990, model CA1060VKA2, 208/230 volt single phase, charged with R-22. The “060” in that model number means roughly five tons — 60,000 BTU of cooling. By the nomenclature it reads like an ICP-family unit (the Heil / Tempstar / Comfortmaker lineage), though the plate itself just says “Air Conditioner,” so I'll leave the badge at that. And here's the kicker, standing right there looking at it: that unit is still running. Thirty-six years old, original, on a refrigerant that's been phased out of production — and it's still making cold air. I have a lot of respect for that. They built those old ICP-style boxes like tanks. But I'll be straight: it's living on borrowed time, and I'll get to why.
Here's the part that makes this job harder than it looks: the air handler for that condenser is up in the attic, above the sanctuary. Return air pulls UP through the ceiling to the handler, the cold air comes back down into the room, and the whole thing is sitting over the congregation's heads. And getting up there is no picnic — the attic access is on the curved part of the sanctuary ceiling, so you're climbing up into a tight, awkward space over a vaulted room just to lay hands on the equipment. Any service, any changeout, any coil work means dealing with that access first. That's the kind of detail that doesn't show up in a quote until you're standing under it.
So what do you actually do? (The honest version)
Here's where I'll be straight, because the wrong answer is to walk in and oversell these people a system they can't afford and don't need. This is a 45-person mission congregation in a stone building with effectively no insulation — solid masonry walls, single-pane stained glass, a slate roof, a stone basement below and a cramped attic above. That's a very different animal from a house or a rooftop job. So you design for what's real:
- Plan for the R-22 unit's exit, don't pretend it's forever. That 1990 condenser doesn't owe anybody a thing — but R-22 hasn't been produced since 2020, and what's left is expensive and getting worse. The honest move isn't to dump money chasing a leak on a 36-year-old machine. It's to run it until it gives up, and have the changeout planned: a modern condenser and a matched coil on today's refrigerant. Budget for it now so it isn't an emergency in July.
- Right-size the replacement — resist the urge to go bigger. The reflex on a stone building that feels hot is to throw more tonnage at it. Wrong move. Stone has huge thermal mass: it's slow to heat up and slow to cool down. An oversized unit will short-cycle, never run long enough to pull humidity, and leave the place clammy. A right-sized system runs longer, gentler cycles — and long runtime is what actually dries the air out and keeps a crowd comfortable.
- Respect the thermal mass instead of fighting it. That stone is not all bad news. Once you get it to a stable temperature it holds it. For a building used hard a few hours on Sunday and quiet the rest of the week, that argues for steady, moderate setpoints and getting the system going well before the doors open — not blasting it cold at the last minute and chasing the mass all morning.
- Insulate where you honestly can — without touching the historic fabric. You are not spray-foaming the inside of a stone church, and you shouldn't. But Port Deposit is a regulated historic district, so anything visible from the street needs a Certificate of Appropriateness anyway. (Town of Port Deposit.) The honest wins are hidden: insulate and air-seal at the ceiling/attic plane — right where that air handler lives — and around the basement rim, where nobody sees it and where you knock down the biggest loads.
- Tidy and label what's already there. That hand-scrawled panel and the taped plenum aren't failures — they're a small church taking care of itself on a budget. But before any new equipment goes in, the supply plenum gets sealed properly, the duct gets checked for leaks in the basement and the attic, and the panel gets a clean, legible directory. Cheap, and it makes the next person's job — and the next emergency — ten times easier.
That's the whole job in a building like this. Not the fanciest system — the honest one. Keep a 150-year-old stone church comfortable for the people who still show up on Sunday, respect the building and the budget, and leave it better labeled and better sealed than you found it.
Why it stuck with me
Most of my work is big commercial rooftops — steel, tonnage, swap it and go. This was the opposite. A little stone mission church, built out of the same rock as Fort McHenry, wedged onto a cliff to survive a river that kept trying to erase the town, still serving 45 people every Sunday — and still leaning on a condenser older than a lot of the contractors who'd quote it. The right answer here was never the biggest box on the truck. It was the honest one: keep what works running, plan the changeout before it's a crisis, and treat the building with the same respect the people who built it did.
If you're ever driving through Port Deposit, slow down on Main Street and look up at the stone. There's a whole town's history in those walls — a spring still running out back, and a church that's been quietly keeping the faith, and fighting the river air, for over a century.
Sources & honest notes: The two-names question (St. Teresa of Avila is the historic congregation at 162 N. Main St., Port Deposit; Church of the Good Shepherd in Perryville is the parent parish that administers it; Roman Catholic, Diocese of Wilmington) is confirmed by the Diocese of Wilmington 2026 parish directory, the Iron Hill Deanery Pastoral Plan, and GCatholic. Mission founded 1857, named 1866; Good Shepherd Parish established 1949; ~45–50 weekly attendance — all from those diocesan sources. Port Deposit granite/gneiss history and its use in the Naval Academy, Fort McHenry, the Boston Public Library and the U.S. Treasury from Port Deposit Gneiss; town terrain, flood/ice history, the 1904 Great Ice Flood, and the 1978 National Register Historic District (NRHP #78001452, MHT CE-1291) from the Maryland Historical Trust, Port Deposit, Maryland, Uncharted Lancaster and the USGS; historic-district review requirement from the Town of Port Deposit. The natural spring still feeding the church out back, and the overflow hose set into the channel beside it, are my own field observation on site — offered as what I saw, not from a written source. Equipment details (manufactured 6/1990, model CA1060VKA2, 208/230V single-phase, R-22, ~5 ton/60,000 BTU, ICP-family nomenclature; Williamson furnace; Square D QO panel) are read directly off the nameplates and cabinets in the field — I name only what's printed on the equipment. R-22 production phase-out (ended 2020) is the basis for the “borrowed time” note. The exact construction year of the stone building, the architect, and the 162-vs-164 N. Main address variation could not be verified from available sources and are presented as open questions, not facts.
About the author: Gregory Frazier is a heavy commercial HVAC estimator working Maryland, Pennsylvania, Delaware, Virginia and Florida for 25+ years. Read his story →