About Denoco Energy Systems
Denoco is a second-generation company built in Eastern Ontario. We're not trying to be the biggest. We're trying to be the most honest — and the easiest to trust in an industry that's trained homeowners to expect the opposite.
What makes Denoco different from other HVAC and plumbing companies?
Denoco's difference is process and truth. We size systems for real loads, explain trade-offs in plain language, and document the work so you know what you're paying for. We don't sell “upgrades” by default, and we won't promise timelines dispatch can't keep. The goal is a safer, healthier home — and zero surprises.
Forty years of showing up (and a second generation raising the bar)
Denoco started as a trades-first shop in Smiths Falls. Show up. Do the job right. Treat people's homes with respect. Dennis O'Connor built that reputation one call at a time — and the communities around Smiths Falls kept us busy because the work held up.
Today, Denoco is still family-owned. Lucas O'Connor (second generation, Owner & Business Systems) leads the Kingston expansion. The Kingston branch is co-owned by Evan Larkin (Certified Plumber, 313D Refrigeration, Sheet Metal Installer, G2 Gas, WETT and more). Same foundation, expanded capability.
Straight answers, premium standards, and a healthier model for the trades
We believe homeowners deserve the truth — and tradespeople deserve a career that doesn't cost them their health. That's not a slogan. It shows up in how we scope work, how we communicate, how we keep sites clean, and how we hold a high standard without hiding behind jargon.
- We explain what we found before we start replacing parts.
- We document what we installed and how it was set up.
- We build plans that still make sense if rebates change.
- We'd rather turn down work than do it halfway.
Do you do residential or commercial work?
Denoco focuses on residential and light commercial work in Eastern Ontario. If a project is outside our scope, we'll tell you quickly and help you find the right fit — because “yes to everything” is how bad jobs happen.
Two branches. One standard of work.
Smiths Falls (HQ) handles core HVAC, plumbing, solar/energy, and generator work, serving communities from Ottawa South to Brockville. Kingston extends Denoco's service footprint and adds Kingston-only specialties like radon mitigation, WETT/wood-energy work, chimneys, and fireplaces, serving Kingston, Napanee, Gananoque, and surroundings.
If you're unsure which branch to call, use your postal code. If your prefix is shared, we'll ask one quick question and route you correctly.
Find your branch →
We live here
We're involved in Eastern Ontario because this is home. You'll see it through Good Deed days and initiatives like HED Start — not as marketing theatre, but as a habit.
Licensed: TSSA FS R0076487578 (G2 gas) · ECRA/ESA 139417 (electrical)