Why Choose Hydronic Heating?

Why Choose Hydronic Heating?

By: First Supply

With a little bit of planning hydronic heating can be a great HVAC solution for many commercial and residential structures. When considering a hydronic system an important point to remember is that these systems use a boiler to provide heat, instead of a furnace. A major difference between traditional furnace heating and hydronic heating is that hydronic systems provide even heat that warms the surface of everything inside of a space, instead of heating the air. Forced air furnace systems blow warm air into a space to displace cooler air, which creates uneven heat and stratification due to hot air rising and cooler air sinking. Hydronic heating systems are also a lot less drying than forced-air systems, especially during winter months.

How do Hydronic Heating Systems Work?

Hydronic systems use hot water (heated by a boiler) and a heat exchanger to transfer warmth. In older homes, hydronic systems circulate hot water to cast-iron radiators. Modern systems deliver hot water (or steam) to smaller baseboard heaters, hydronic coils, or radiant floor systems.

As heated liquid circulates through the system, heat is transferred from the hot liquid through thermal radiation and natural convection. In radiant floor systems, heat is transferred from radiant loops installed under flooring to the floor surface, and then to the space. These systems provide the benefit of warm floors at the same time as they deliver heat. Radiator systems transfer heat directly to the ambient air.

Can Hydronic Systems Cool?

In residential applications, hydronic systems can’t cool on their own, but they are often paired with a mini split unit that can provide cooling.

In commercial applications cooling can be achieved with a hydronic system. But cooling doesn’t occur by introducing cold air, instead heat is removed from the air. In other words, hydronic cooling uses chilled water as a heat exchange medium to remove heat from a space. While evaporative cooling adds humidity into a space, hydronic cooling is a closed loop meaning that nothing is added or removed. In hydronic cooling, fluid in the system is chilled by a chiller coil, dry cooler, or cooling tower and pumped through the hydronic loop system into before returning to the chiller. As the fluid circulates through the system warm air is pulled in and over the heat exchanger. During this process heat is transferred from the air and absorbed by the cool water inside the coil. This action removes heat and humidity from the room to leave cool, dry air. The warm water inside the system is immediately returned to a chiller and the process repeats.

Components of a Hydronic System

Every hydronic system requires a way to heat water. The most basic setup consists of a hydronic air handler connected to a heat source. After water is heated, a circulator pump moves water through the air handler coil loop. Hydronic air handlers then blow heated air from ductwork vents. It’s common for hydronic systems to be set up for zone heating where each zone has its own thermostat and can be controlled independently from other zones. When the end user sets a zone thermostat, the system directs water from the water heater/boiler to a corresponding heating coil. Following is a list of common components used in a hydronic system.

Air Separators

Traps dissolved air in a hydronic system and expels it through a built-in air vent.
See Air Separators

Air Vents

Provide automatic venting of dissolved air in a hydronic system.
See Air Vents

Backflow Preventers

Prevents circulated water from returning to the domestic water supply.
See Backflow Preventers


Heats water before it’s circulated through the system. Water can be heated using gas, electricity, oil, or wood depending on the type of boiler.
See Boilers

Circulating Pumps

Circulates water through a boiler and into a piping system. A hydronic system might have more than one circulating pump if multiple zones exist.
See Circulating Pumps

Chiller Cooling Coils

Air is cooled as it travels through coils that are chilled with water, ethylene, or propylene glycol.
See Chiller Cooling Coils

Expansion Tanks

Regulates expansion pressure created by hot water to provide consistent pressure to prevent damage to pipes in a hydronic heating system.
See Expansion Tanks

Fill Valves

Allows water to enter the system until the desired pressure is reached.
See Fill Valves

Heat Distribution Equipment

Radiators, baseboard heaters, and radiant floor coils are used to disburse heat to different areas.
See Heat Distribution Equipment

Heat Exchangers

Transfers heat to the water (or alternate fluid) used in the system.
See Heat Exchangers

Mixing Valves

Helps regulate temperature by mixing in cooler water.
See Mixing Valves

Pipes and Fittings

Pipes that carry hydronic liquid will commonly be made of PEX, PE-RT, or PEX-AL-PEX. Piping and fittings must be certified and rated for hydronic distribution.
See Pipes and Fittings

Strainers or Hydronic Filters

Remove sediment and suspended solids from closed loop systems to protect seals, valves, and piping.
See Strainers or Hydronic Filters

Shut Off Valves

Controls water flow in your hydronic system.
See Shut Off Valves

Zone Valves (Control Valves)

Regulates flow to a specific zone in a hydronic heating system.
See Zone Valves (Control Valves)

Hydronic Accessories

For a successful installation of a hydronic HVAC system, several accessories may be required. First Supply has a great selection of condensate pumps, pipe supports, low water cutoffs, hydronic thermostats, and more. The following are different accessories that may be required to install a hydronic system.

Condensate Pumps

Necessary for to remove condensate in hydronic systems unable to discharge water with a gravity feed. Power turns on when water accumulates to a set level.
See Condensate Pumps

PEX Routing Systems

Supports and organizes PEX tubes during installation.
See PEX Routing Systems

Pipe Supports

Allow optimal positioning of the piping that carries hydronic fluid.
See Pipe Supports

Low Water Cutoffs

Protects pumps from running dry in condensate tank applications.
See Low Water Cutoffs

Hydronic Manifolds

Distribute mixed-temperature water to different heating zones.
See Hydronic Manifolds

Hydronic Thermostats

Turns heat on/off according to the set temperature.
See Hydronic Thermostats

Special Considerations

Hydronic heating is significantly different from a traditional HVAC system and requires significant installation. You can read about the Pros and Cons of Hydronic Heating before committing to this type of system.

Comfort Zone

Choosing the right heating and cooling system can play a huge part in the comfort that a property owner will enjoy in the long run. The information in this article should give you the tools you need to weigh the features and benefits of a hydronic heating system against the negatives. Trust First Supply for all your hydronic equipment, PFV, supplies, and information.

See all Hydronics at First Supply!