New Construction & Remodeling HVAC in Southeast Wisconsin

Planning a New Home or Major Remodel? Design the Comfort System In From the Start

The best time to get heating and cooling right is before the drywall goes up. O'Leary Plumbing, Heating & Electrical has designed and installed HVAC systems for new construction, additions, remodels, and retrofits across Southeast Wisconsin since 1958 — for general contractors, custom builders, and homeowners managing their own projects. Bring us your blueprints and we'll sit down with you for a free estimate, then engineer a system that fits your plans, your timeline, and your budget.

Why Does HVAC Design Matter So Much in New Construction?

Because almost every comfort complaint we're called to fix in an existing home traces back to a decision made during construction. Undersized returns that starve the system for air. Duct runs that were an afterthought, leaving bonus rooms hot in July and cold in January. Equipment sized by square footage alone instead of a real load calculation. These problems are cheap to prevent on paper and expensive to correct after the fact.

When we design a system for your project, we start with the building itself — orientation, insulation values, window placement, ceiling heights — and size the equipment to the actual load. We lay out ductwork for even airflow and quiet operation, plan equipment locations for serviceability, and coordinate with your other trades so the mechanical systems go in smoothly instead of fighting the framing. It's the difference between a house that happens to have a furnace and a home that's genuinely comfortable in every room, in every season Wisconsin throws at it.

What Systems Can We Design and Install?

We're a full-service designer and installer for both residential and light commercial projects. Depending on the building and your priorities, that can mean a high-efficiency furnace installation paired with central air conditioning, a boiler serving in-floor radiant heat — a favorite in this region's custom homes and heated garages — an air-source heat pump, or a ductless system for a space where running ductwork doesn't make sense.

Additions and remodels get the same engineering attention. Sometimes the right answer is extending your existing ductwork; sometimes it's a dedicated system for the new space so the original equipment isn't strained beyond what it was sized for. We'll tell you which is which, with numbers, before you commit.

What About Ventilation and Air Quality?

Modern construction is tight, and a tight house needs deliberate ventilation. We design fresh-air strategies appropriate to the build — including energy recovery ventilation where it's warranted — plus filtration, humidity control, and duct layouts that keep air moving where it should. If you're remodeling around existing ductwork, our duct repair and sealing work ensures the old runs don't undermine the new system. The goal is simple: air that's fresh, clean, and evenly conditioned throughout the finished space.

How Do Energy Efficiency and Operating Costs Factor In?

A new-construction project is a once-in-decades chance to lock in low operating costs. High-efficiency equipment, right-sized and installed with sealed, well-designed ductwork, costs meaningfully less to run every month for the life of the home — and in our climate, with long heating seasons and humid summers, that's a large number over twenty years. We'll walk you through the efficiency tiers that make sense for your project, flag any utility rebates or incentive programs that current equipment qualifies for, and give you honest guidance on where extra efficiency pays for itself and where it doesn't. You make the call with real information, not a sales pitch.

Why Do Builders and Homeowners Choose O'Leary?

Three generations of the same family have run this company since 1958, and a large share of our new-construction work comes from builders and homeowners who've worked with us before — or who were referred by someone who has. Our technicians are licensed, bonded, and insured. We show up when the schedule says, coordinate cleanly with your other trades, and stand behind the finished system after the project wraps. Because we also handle plumbing and electrical work, many projects consolidate all three mechanical trades under one company, which means one point of contact and no finger-pointing between subs.

Frequently Asked Questions About New Construction HVAC

When should the HVAC contractor get involved in my project?

Earlier than most people think — ideally while plans are still on paper. Equipment locations, chase routes for ductwork, and return-air paths are easy to accommodate during design and expensive to bolt on after framing. Bringing us blueprints before the build starts is the single best way to get a quieter, more even, more efficient system.

Do you perform load calculations, or size by square footage?

We size every system from a real load calculation based on the building's orientation, insulation, windows, and layout. Square-footage rules of thumb routinely oversize equipment, which causes short-cycling, poor humidity control, and uneven rooms — the exact problems good design exists to prevent.

Can you replace the HVAC as part of a remodel without redoing everything?

Usually, yes. We evaluate what your existing equipment and ductwork can properly support, then tell you honestly whether the addition should tie into the existing system or get its own. The wrong answer to that question is the source of half the "the new room is never comfortable" calls we run.

Do you coordinate with my general contractor?

Every day. We work from your builder's schedule, show up when the project needs mechanical rough-in and again at finish, and coordinate with the electrician and plumber — often because we ARE the electrician and plumber, which keeps three trades moving on one schedule.

Start Your Project With a Free Estimate

Whether you're breaking ground on a custom home, adding a room, or gutting a kitchen down to the studs, get the comfort system designed right from day one. Mail or drop off your blueprints, reach us online, or call O'Leary Plumbing, Heating & Electrical at (262) 642-7747 to schedule a free new-construction HVAC estimate anywhere in Southeast Wisconsin.