hot water radiators

The use of boilers

The hot water used in modern radiators is often obtained through boilers. Boilers can run on biomass fuel (pellet and wood), which is a good environmental and economic choice, but more common and less environmental options involve gas and oil high efficiency condensing boilers.

Note: electric boilers aren't a true economical alternative, except for small and sporadic heating needs.

Solar & Hot water radiators

Radiators demand large volumes of hot water and high water temperatures (around 150º-160º F/65º-71ºC), and solar hot-water systems alone can’t provide them. If you want to connect a solar water system with radiators, you should also use a boiler, to rise the hot-water temperatures.

See: Solar Hot Water Systems and Radiators.

Problems with hot water radiators

The most common problem with hot-water radiators is unwanted air in them. To expel that unwanted air you should - typically at the start of the heating season - open each radiator bleed valve slightly while the system is running, and close the valve when water starts to escape through it. Repeat the operation in each radiator. For multi-level homes start at the top floor.  

Radiators, home zones and thermostats

Use programmable thermostats to get energy savings from hot-water radiators. An excellent solution to get higher energy savings is to install automatic valves, typically controlled by a set of thermostats located in each room or part of the building.

These thermostats will switch your baseboard heater on or off at bedtime and out-of-home situations, matching your personal and more convenient usage patterns.

Home zones and hot water radiators

To achieve higher energy savings you should zone your home, that is, you may implement separated zones within the home, with different temperatures controlled by different thermostats. This solution demands the existence of rooms not being used or only used in different schedules.

Home zoning may also demand reasonably insulated rooms: closing doors is necessary but often insufficient.

Note: in very cold climates, temperatures below 40-50ºF/4-10ºC cause water pipes to freeze. To avoid it, rooms and unused parts of the house shouldn’t be entirely insulated.