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.