Before any numbers: every figure on this page is a broad national planning range, not a quote. Hydronic costs vary widely by region, home, fuel type, code requirements, and the condition of your existing system. Two identical-looking projects a few miles apart can land thousands of dollars apart for legitimate reasons. Use these ranges to sanity-check proposals and budget realistically — not to judge whether a specific bid is "fair" without understanding its scope.
Boiler replacement: roughly $6,000–$15,000+ installed
A straightforward swap of an existing boiler in the US typically lands somewhere between about $6,000 and $15,000 installed, and complex projects can go higher. The spread is that wide because "replacing a boiler" can mean very different amounts of work:
- Condensing vs. cast iron. A modern condensing boiler costs more up front than a conventional cast iron unit, but extracts more heat from each unit of fuel — often 90%+ efficiency versus roughly 80–85%. Condensing boilers also require a condensate drain and different venting, which adds installation scope.
- Venting changes. Cast iron boilers usually vent through a chimney; condensing boilers vent through inexpensive plastic pipe out a sidewall, but rerouting venting — or relining an orphaned chimney that a water heater still uses — adds real cost.
- Code upgrades. When a permit is pulled (and it should be), the installation must meet current code. That can mean new gas piping, combustion air provisions, an expansion tank, backflow prevention, electrical work, or seismic strapping that the old installation never had.
- Near-boiler piping and controls. A quality installer often corrects decades of piping shortcuts — adding proper air separation, isolation valves, and modern controls — which costs more than reconnecting to whatever was there.
In other words, the price difference between two boiler quotes is usually a scope difference, not a markup difference. A quote that simply reconnects a new boiler to old, flawed piping will be cheaper — and often worse.
Radiant floor heating: new construction vs. retrofit
Radiant floor heating is most affordable when the tubing goes in before the floors do. In new construction or a full floor replacement, installed costs often run roughly $8–$15 per square foot. Retrofitting radiant into a finished home typically runs higher — often $15–$25 or more per square foot — because the installer has to work around what already exists: opening ceilings to staple tubing under the subfloor, pouring a thin overlay slab that raises floor heights, or removing and replacing finish flooring.
Retrofits also frequently need supporting work that new construction doesn't: adding insulation below the tubing, upgrading the heat source, and running new piping through finished walls. If you're planning a remodel that will open up floors or ceilings anyway, that's the moment radiant becomes far more affordable. Our radiant floor heating guide covers the installation methods in detail.
Snowmelt systems: installed and operating costs
Heated driveways and walkways typically cost roughly $20–$40 per square foot installed when done during a new pour, which puts a full driveway in the low-to-mid five figures. The main installed-cost drivers are:
- Area. Cost scales almost directly with square footage — a full three-car driveway is a very different project than an entry walk and steps.
- Glycol system. Outdoor loops need a glycol/water mix, a heat exchanger to separate it from the house loop, and periodic fluid maintenance.
- Boiler capacity. Melting snow takes a lot of heat. If your existing boiler doesn't have spare capacity, the project must include a larger or dedicated heat source, which can add substantially to the price.
Operating cost is a separate question and depends almost entirely on run hours: a smart control that fires only during snowfall costs far less to run per season than a system left idling warm all winter. Climate, fuel prices, and control strategy matter more than the equipment brand. See our snowmelt systems guide for how these systems work.
Air-to-water heat pumps and geothermal
Hydronic systems can also run on electricity via air-to-water heat pumps or ground-source (geothermal) heat pumps. Both cost more up front than a gas boiler — air-to-water systems typically land above comparable boiler installations, and geothermal adds the significant cost of drilling or trenching a ground loop, often pushing whole-system costs well into five figures.
Two things offset that premium. First, incentives: federal tax credits and state or utility rebates may apply to heat pump and geothermal installations, and can meaningfully change the math — check what's available in your area before ruling anything out. Second, operating cost: in many climates and at many utility rates, heat pumps cost less to run than fossil-fuel boilers, especially when paired with low-temperature radiant floors that let the heat pump work in its most efficient range.
What makes quotes differ
When homeowners collect three bids for the same project, the numbers often vary by 50% or more. That's not necessarily anyone being dishonest — it usually reflects genuine differences in:
- Design work. Did the contractor perform a room-by-room heat loss calculation, or size the equipment by rule of thumb ("same size as the old one")? Real design work takes time and shows up in the price — and in the comfort and efficiency of the finished system.
- Scope. Venting, gas piping, code corrections, near-boiler piping, controls, and cleanup are included in some bids and excluded (or ignored) in others. Compare line by line.
- Equipment tier. Boiler brands and models differ in efficiency, modulation range, and expected lifespan.
- Warranty and service. A longer labor warranty and a contractor who will actually answer the phone in February have value that a one-line price can't show.
- Overhead and licensing. Insured, licensed, trained crews cost more to field than a truck-and-a-helper operation — and hydronics rewards training.
Why the cheapest bid is often the most expensive system
Hydronic heating is a designed system, not an appliance. An oversized boiler short-cycles itself to an early death; an undersized one leaves rooms cold; sloppy piping causes air noise, uneven heat, and callbacks for years. The few thousand dollars saved on the low bid is routinely spent several times over in fuel, repairs, and early replacement. Judge bids on the quality of the questions the contractor asked and the design work they did — the sticker price is the least informative number on the page.
The single best step you can take before spending anything: insist that any contractor quoting your project performs a room-by-room heat loss calculation for your actual home. It's the foundation every good hydronic system is built on. If you're in Utah, see our guide to finding a Utah hydronic installer, where we recommend Phillips Hydronics for readers along the Wasatch Front and beyond.