Hot water radiator systems

A hot water radiator system involves a boiler, a pump and a net of room radiators connected by water piping.

The water is heated in the boiler to temperatures above 120ºF and is then pumped - through piping - into the room radiators.

See also: Hot water baseboard heating

Fuel

The boilers used in radiator systems can run on gas, propane, oil, pellets, electricity (electric boilers are a typical un-economical alternative in this type of systems)...

Solar powered systems can also be added to the system, but only to supplement it: radiator and baseboard systems require large volumes of water at high temperatures (around 150º-160ºF/65º-71ºC, on average) that solar hot-water systems can’t provide. Besides you should also consider compatibility and design issues. See, for details: Solar Radiator Heating

Problems with hot water radiators

The most common problem with hot-water radiators is unwanted air. To expel unwanted air you have to carry on a small operation, usually at the start of the heating season: open each radiator bleed valve slightly while the system is running, and close the valve after water starts to escape... Repeat the operation in each radiator. For multi-level homes, start at the top floor.

Radiators, home zones and thermostats

Hot water radiator systems involve a high initial investment (often above $5,000-$6,000), and large amount of water at high temperatures, which can make them non-competitive. They provide a healthy and high-quality heating, but to be competitive they demand some major preconditions: 1) an integrated system (hot water for baths and kitchen) eventually linked to a solar powered system, 2) a cold climate (baseboard and radiator heating is rarely a good heating solution for other climates); 3) a good insulation of the home’s envelope (to reduce the heating needs) and 4) a proper zoning strategy to provide energy savings and energy-efficiency (see text at left).

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, matching the heating needs to your personal usage patterns.

Hot Water Radiators Efficiency

To achieve high energy savings and energy-efficiency with a hot water radiator system, consider using home zoning strategies, that is, consider using several zones/rooms with different temperatures.

These strategies rely on programmable thermostats to adjust the heating loads to different schedules and patterns of use. Home zoning also requires reasonably insulated rooms (including doors capable of zoning a room).