Hydronic heating work is the water-based side of the heating trades: technicians install and service boilers, pumps, piping and radiant or baseboard systems that move heat through a building as hot water.
It is a specialty both HVAC technicians and plumbers grow into rather than a trade of its own — and its installed base is concentrated: the Northeast holds 6.01 million of the 9.29 million U.S. homes heated mainly by a steam or hot-water system.
Here is what the specialty involves, and where it leads.
What hydronic heating systems are
Hydronic describes any heating system that moves its heat with water.
A boiler warms water without boiling it, a circulator pump pushes that water out through sealed piping to the heat emitters — radiators, baseboard, or tubing set in the floor — and the cooled water cycles back to the boiler to be reheated.
No ductwork and no supply air: just a closed loop that repeats for as long as the thermostat calls for heat.
The emitters give the systems their everyday names.
Radiator and baseboard systems are the classic hydronic setup.
Hydronic radiant floor heating hides the emitters entirely: loops of tubing in or under the floor turn the floor surface itself into the radiator.
Both are fed by the same kind of boiler — what differs is how the heat enters the room.
One boundary keeps the specialty straight: hydronic systems circulate water that stays liquid.
Steam systems boil the water and move the vapor itself — a sibling technology with its own water lines, vents and traps.
Our boiler technician guide walks through the hot-water-versus-steam split in detail, and the rest of this page stays on the water side.
Who does hydronics: HVAC techs or plumbers?
Both trades do hydronics, and that is the honest starting point.
The heat source is heating equipment; the distribution is piping — the plumber's material — and that puts the specialty astride both trades.
If you are still weighing which trade to enter, our HVAC vs plumbing comparison covers the full decision; hydronics is the overlap zone where either path can land.
The licence map draws the lines differently from state to state.
Iowa issues master licences in plumbing, mechanical, HVAC-refrigeration and hydronic, and journeyperson licences in plumbing, mechanical, HVAC-refrigeration, sheet metal and hydronic — so hydronic professionals have a licence discipline of their own there.
North Carolina splits its heating licences into three groups, with Heating Group 1 covering water-based hydronic comfort heating.
Ohio's Construction Industry Licensing Board (OCILB) houses hydronics beside plumbing: its plumbing and hydronics section has primary responsibility for licensing plumbing contractors and hydronics contractors.
Nevada's C-1d Plumbing contractor classification includes hydronic heating systems up to 200,000 BTU.
And Massachusetts goes the other direction: its plumbing rules do not count HVAC work — heating systems, steam and hydronic heat piping — as qualifying experience toward the journeyman plumber licence.
Read those together and the pattern is clear: the same specialty can sit inside a heating licence, inside a plumbing classification, or stand as a licence discipline of its own — state by state.
Which licence you carry decides which jobs you can take, so check the coverage where you live and work — not in the state next door.
Confirm what your licence covers before you take the work
Core hydronics skills: piping, pumps, controls, mod-cons
The specialty rewards technicians who are comfortable on both sides of the boiler — the wet side and the control side.
The skill stack breaks into four groups.
Piping and near-boiler piping.
The pipe work spans copper soldered or pressed, steel threaded, and PEX run in radiant loops.
Near-boiler piping is the assembly right at the boiler — the closely packed group of fittings, valves and pumps that sets how the whole system flows: where the expansion tank connects, where air is separated from the water, how the circulators are arranged.
Clean near-boiler piping helps make a system quiet, balanced and serviceable for the technician who follows you.
Pumps and flow.
Circulators move the heat; around them sit expansion tanks, air separators and fill valves.
Servicing this side of the loop means reading pressure and temperature gauges, balancing flow between zones, and chasing air out of loops that have lost their quiet.
Controls.
Zone valves, thermostats, relay panels and boiler controls decide where the heat goes and when.
Water-temperature reset controls trim the boiler's water temperature against outdoor conditions.
On a no-heat call, the diagnostic trace runs from thermostat to zone valve to circulator to boiler.
Mod-con boilers.
Modulating-condensing boilers — mod-cons — change their firing rate to match the building's heat load instead of cycling fully on and off, and they condense water vapor out of the exhaust to capture heat before it leaves the flue.
Servicing them leans on combustion measurement and clean system water — which is why the specialty has its own learning curve.
Radiant floor heating work
Hydronic radiant floor heating puts the heat emitter underfoot: tubing loops laid across the floor area, warm water circulating through them, the floor itself radiating heat into the room.
It is work that runs through both new construction and renovation.
The installer's side of the work is layout and discipline: planning tubing runs and spacing, mounting and piping the manifolds that feed each loop, pressure-testing the loops before floors close in, and labeling circuits so the next technician can service them.
Coordination is part of the job — the tubing goes in on the framing and rough-in schedule of the other trades, not the heating schedule, so radiant installers work alongside general contractors and floor-covering crews.
The service side is flow.
A zone that will not warm is traced loop by loop, and the fix is measured at the manifold — balancing individual loops, purging air, and verifying the supply-water temperature the loops are running on.
Because radiant work is piping-first, it is one of the clearest places the two career paths converge: the same tubing-and-manifold skills a plumber builds on water piping transfer directly, and HVAC-side technicians pick them up as they move into hydronic heat.
It is also a recognized specialization — the Bureau of Labor Statistics lists radiant heating systems among the areas HVAC technicians specialize in, alongside testing and balancing and commercial refrigeration.
Where hydronics jobs are
The boiler side of the trade is heavily concentrated in one region — with one framing caveat: the federal survey counts steam and hot-water systems as a single category, so its figures size the boiler market, not hydronics alone.
EIA's 2020 Residential Energy Consumption Survey counts 9.29 million U.S. homes — about 7.5% of 123.53 million — heated mainly by a steam or hot-water (boiler) system, and 6.01 million of them, 65%, are in the Northeast.
In the Northeast, 6.01 million of 21.92 million homes — 27% — use a steam or hot-water system as their main heating equipment, versus 7% in the Midwest.
Fuel oil deepens the same pattern: 4.07 million of the 4.93 million U.S. homes that heat mainly with fuel oil or kerosene — 83% — are in the Northeast.
Our boiler technician guide walks the region-by-region counts and the fuel-oil angle in full.
For a technician, the practical read: the installed boiler base — steam and hot-water counted together — sits first in the Northeast, then the Midwest.
Where hydronics-specific and radiant-floor installation volume sits, our research cannot say: we hold no national installation-volume data to size that side of the work, and the verified numbers above are the combined boiler base.
Hydronics work runs under several job titles — hydronics technician, hydronic heating technician, radiant heating installer and boiler technician are all names for this specialty — so search the trade rather than one string.
Current openings are collected on the boiler technician jobs page.
On pay: our sources carry no hydronics-only wage series.
The boiler technician salary page shows the data the boiler technician role is measured against — SOC 49-9021, the broader heating-and-cooling occupation it sits inside.
Career information, not legal advice. Licence coverage for hydronic work varies by state and city — confirm the current requirements with your state licensing board, or the city or county where licensing is local.