Flushing the System: To flush a hot water heating system, follow these steps: Turn the system off, close the water feed valve to the boiler, and let the system cool. Connect a hose to the drain valve that's located on the bottom of the boiler and run the hose to an indoor or outdoor drain. Open the air vent on the highest radiator to break the vacuum. Then open the drain on the boiler and let the entire system drain. Once it drains, close the radiator valve, open the feed valve, and flush water through the boiler until the water runs clean. Close the drain valve on the boiler and let the system refill. Re-start the boiler (even if it's summer) to purge air out of the system. Consult your owner's manual for more specific instructions before you start. If you feel uncomfortable attempting this maintenance, let your service contractor do it the first time while you watch and take notes. Depending on how old and dirty the system is, you may want the contractor to "power flush" it using special chemicals. Safety: If you find a white, cloth-like sheathing wrapped around your pipes or boiler, it could be asbestos. Don't attempt to patch or remove it. Call your heating contractor immediately. If asbestos is disturbed, it will disperse microscopic particles into the air, a potential respiratory hazard.
Money-Saving Tip: During mild weather in the fall and spring, you can save money on your fuel bill by lowering the setting on your aquastat (the boiler's control device) at 140 degrees (F) on the high limit and 120 degrees on the low. (The typical settings for cold winter weather might be 180 degrees and 160 degrees, respectively.) If you don't know where the aquastat is, consult your owner's manual or ask your heating contractor.
For best performance, clean your radiators periodically using a soft brush or vacuum with a brush attachment. On some baseboard radiators you may have to remove the top or front plate to clean between the fins. Leave a few inches of clearance between radiators and any nearby drapes, rugs, furniture, or electrical cords. This eliminates any chance of fire and lets the radiator work better by letting room air flow freely up through the fins.
At least once each heating season, bleed the air out of each radiator. Hold a container under the radiator valve and open it with a radiator key -- you can pick one up at a hardware store. When only water comes out, close the valve.