Baseboard and other hydronic (hot water) heating is typically expensive. But there are some ways of making it less expensive, especially by using thermostats, zoning and valves and aquastats.
Room thermostats & control Hot Water baseboard Running Time
Room thermostats are important to turn the heating system on and off according to the heating needs and occupancy of the rooms; and also to control the boiler or the circulator/pump according to the needs.
The key is to get a the right type of thermostats, able to work with your boiler's control wiring (many programmable thermostats are now compatible with hot-water baseboard heating systems).
To achieve better results, the room thermostats should be properly located.
Avoid locating them near secondary heating sources (electric fireplaces, gas or wall vented heaters), or in areas close to windows and doors, or near stoves and heat sources; and do not forget that thermostats need a free flow of air to sense the temperature; they must not be blocked by furniture or curtains.
Try to turn your thermostat down a degree or two, and see if your family members still feel comfortable. Room thermostats should be set to the lowest comfortable temperature (say, 65ºF/70ºF 18°C/21°C). You may reduce your heating bills by 5% for every degree you lower your thermostat.
If you are having problems finding the right thermostat, contact a good heating contractor familiar with hot water baseboard heaters.
Thermostatic radiator valves
Thermostatic radiator valves (TRV) are a way of providing individual control of radiators, convectors or hot water baseboard units.
So, consider different temperatures for the different rooms by installing TRV valves.
TRV valves can reduce the flow of water through each baseboard or radiator, allowing lower temperatures. A lower setting uses less hot water and can save you a lot of money.
For a technical PDF: Honeywell: Thermostatic Radiator Valves
Boiler aquastat and controls
Make sure that your boiler doesn't fire unless there is a demand for heat (coming from the room thermostats associated to the hot water baseboard heaters). Many poorly controlled systems allow boilers to run according to internal temperature settings, wasting energy.
Modern boilers have a thermostat (called aquastat) to sense the temperature of the water and to control the burner; the aquastat turns the burner Off or On as needed… Make sure that it is functioning as expected. Many existing baseboard and other hydronic systems circulate and store water at very high temperatures, leading to huge standing losses and overheating.
Thermostats, Thermostatic Radiator Valves and Aquastat manufacturers