While similar in design and purpose, hydronic heaters differ widely from electric baseboard heaters. While both may run on standard AC electrical current, hydronic heaters use radiant heat while electric baseboard units are of the convection variety. These wall units are designed to provide either supplemental heat or serve as the main source of heat. In terms of installation, purchase cost, cost of operation and, of course, heating method, hydronic and electric baseboard units differ.
Hydronic vs. Convection Heat
The main difference between these two heating methods is that hydronic heat emits rays while convection heat emits waves. That's an abstract way of thinking about it, though. Hydronic, radiant heat radiates warmth in much the same way as the sun heats your skin. Convection heaters aren't able to diffuse the heat produced, so they require a fan. You are probably familiar with convection ovens, all of which work by using a fan to circulate heat around the cavity.
Two Types of Hydronic Heaters
Hydronic heaters typically resemble electric baseboard units in terms of design characteristics. They both attach to a wall at the floor level and are long and relatively slim. There are two basic types of wall hydronic heaters: built-in systems and freestanding heaters. Of the two, built-in systems require a more complicated installation and are therefore typically built into a home as it's built. Built-in hydronic heaters evolved from old fashioned cast iron radiators around since the 1940s.
The system consists of a central boiler commonly powered by natural gas, copper piping running through the home, and baseboard heat-emitting units installed in each room or zone. Designed to be permanent, built-in systems can easily be integrated into the layout and décor of a home. Water is heated in the central boiler then piped throughout the house to each zone, transferring the heat to each room through the baseboard units. Once cooled, the water returns to the boiler.
Freestanding hydronic units are self contained. They are built with an ever-present supply of water or other heat-transfer liquid and their own individual thermostat. They are typically powered by electricity. They function in a similar manner to built-in systems, although the water or liquid is heated and reheated in each baseboard unit.
Electric Convection Baseboard Heaters
Like freestanding hydronic units, convection baseboard heaters are powered by electricity. They also feature individual thermostatic control. Instead of heating water to transfer heat, electricity powers up an internal heating element. Cool air at floor level is drawn into the intake vent, heated, then blown with a fan out into the room. Their built-in thermostat regulates the cycle of each unit.
Differences and Commonalities
A built-in hydronic system requires a complex installation and will be expensive for pre existing homes. However, it is one of the most efficient ways to heat a home and is more cost effective in terms of operation. Both types of self-contained wall heaters are far easier to install, but you'll likely pay more for the hydronic variety. Radiant heat has the added advantage of continuing to emit warmth even after the heater switches off, increasing the efficiency of its operation.