Radiant floor heating in northern Utah

A boiler heats water, and pumps move that water through loops of tubing under the floor. The floor warms up and gives off heat evenly across the room.

The main parts are:

• The heat source. Usually a boiler. Radiant floors run on cooler water than baseboards or radiators.
• The mixing valve. It blends the water down to the temperature the floor needs.
• The manifold. It splits the flow into loops and lets us balance each one.
• The tubing. Flexible PEX tubing runs in the slab or under the floor.
• Circulators and zone valves. They send heat to the rooms that call for it.
• Thermostats. Each zone has its own.

A floor buried in concrete heats up and cools down slowly. It holds a steady temperature well, but it does not respond fast to a thermostat change.

There are four common methods. The right one depends on whether the floor is new, how much height you can give up, and what is under it.

• In a concrete slab. The tubing is tied to the reinforcing steel before the pour. This suits new basements, garages, and slab homes.
• Thin slab over a subfloor. A thin layer of concrete or gypsum is poured over tubing on a framed floor. It adds weight and height, so the framing has to be checked.
• Under the subfloor. Tubing and metal heat transfer plates are fastened between the joists from below. It needs open access from a basement or crawl space.
• Grooved panels on top of the subfloor. The tubing snaps into panels under the finished floor. They add little height, which suits remodels.

Every method needs insulation below the tubing so the heat goes up into the room.

Hard, dense floors pass heat most easily. Thick, soft floors hold it back.

• Tile, stone, and polished concrete. These conduct heat well and are the strongest match.
• Engineered wood and laminate. Many products are rated for radiant heat. The flooring manufacturer sets a limit on floor surface temperature, and we set the controls to stay under it.
• Solid hardwood. It can work, but it moves more with heat and humidity. Narrow boards and a slow warm-up help.
• Vinyl plank. Check the manufacturer's temperature limit before you buy.
• Carpet. Thick carpet and pad act as insulation. If you want carpet, choose a thin one with a low-insulation pad.

Tell us the flooring before we design the system. Tube spacing and water temperature change with the floor covering. Area rugs over a heated floor are fine in most rooms.

We plan it on paper first, because tubing is hard to change once it is covered.

1. Heat loss. We calculate how much heat each room needs.
2. Layout. We plan the loops, the tube spacing, the zones, and the place for the manifold.
3. Insulation. Insulation goes under the tubing, and at the slab edge on a slab.
4. Tubing. We lay the loops and connect them to the manifold.
5. Pressure test. We put the tubing under pressure and keep it there while the concrete is poured or the floor goes down. A nick shows up on the gauge right away.
6. Mechanical room. We connect the manifold to the boiler, mixing valve, circulators, and controls.
7. Startup. We fill the system, purge the air, balance the loops, and bring a new slab up to temperature slowly.

We coordinate with your builder, concrete crew, and flooring installer along the way.

We give free estimates. The cost depends on these things.

• Area and number of zones. More floor means more tubing, and more zones mean more valves and thermostats.
• Installation method. Tubing in a new slab is the simplest. Working under or on top of an existing floor takes more labor.
• New build or remodel. Open framing and bare ground are easier than finished rooms.
• The heat source. An existing boiler with spare capacity may serve the floor. Otherwise the job includes a boiler.
• Insulation and floor prep. Both are required for the system to work well.
• Controls. Basic thermostats cost less than floor sensors and outdoor reset controls.

Radiant costs more to install than forced air or baseboard. The work that follows, such as flooring and concrete, is priced by those trades. Financing is available.

Most failures are in the mechanical room, not under the floor.

• One zone is cold. The usual causes are air in the loop, a stuck zone valve or actuator, or a bad thermostat. We purge the loop and test the valve.
• Every zone is cold. We look at the boiler, the circulator, and the mixing valve.
• The floor heats unevenly. The loops need balancing at the manifold, or a loop is air-locked.
• The pressure keeps dropping. Water is leaving the system. We check the relief valve, the manifold, and the fittings first. Then we isolate loops and pressure test them.
• A leak in buried tubing. It is uncommon. Thermal imaging and pressure testing narrow it down, so only that spot has to be opened.
• Noise. Ticking or gurgling points to expansion or air.

A radiant system is full of water, so a boiler failure in deep cold puts the tubing and the house plumbing at risk. In Park City, the normal January low is 15.6°F, and an average of 3.6 January days reach 0°F or colder. The risk is higher in a vacation home or rental that sits empty between guests.

We use four protections:

• Antifreeze. A propylene glycol mix made for hydronic systems keeps the loops from freezing. It moves heat a little less well than water, so we use it where the risk calls for it.
• Yearly testing. Antifreeze breaks down with age. We test its strength and condition.
• Boiler service. A serviced boiler is less likely to quit.
• Low-temperature alarms. A sensor that texts you gives you time to act.