For simple cleaning, start by removing the ashes from the fireplace. During the cold season, make sure that the ashes don't build up to a depth greater than about 2". After the cold season, remove all of the ashes from the fireplace.
Use a flat fireplace shovel to clean out the ashes (Image 1). Place them in a bucket for easy removal and disposal.
Remove any remaining ashes or other dry debris using a shop vacuum with a filter bag (Image 2).
Fireplace ashes can be added to your compost pile.
Removing the soot and fire stains from the firebox will take a little more effort. Start by spraying on a mixture of soapy water. Spray on liberally and let the solution stay on the surface for about 30 minutes.
Once the residue has had a chance to soften, scrub the surfaces using a stiff wire brush.
For stubborn stains, use something stronger than soap and water. Muriatic acid is an abrasive chemical used to clean fireplaces.
Safety Alert: Muriatic acid is a harsh chemical, and is also toxic. Follow all safety precautions printed on the bottle.
Mix one part muriatic acid with 10 parts water, and apply the solution to the brick or stone surfaces of the firebox.
Let the solution remain on the surface for about 30 minutes before scrubbing with a wire brush (Image 1).
Also use a metal brush to remove rust and debris from the damper (Image 2). The damper may be difficult to access, so wear old clothing, eye protection and gloves for this job. Make sure that the damper mechanism is working properly so that the damper can open and close freely.
Chimney maintenance is a job for professionals, but there are a few things you can check for yourself.
Make sure that the chimney cap (Image 1) is in good condition, and that it does not become clogged with leaves or other debris.
A wire screen will keep debris and animals from getting down into the chimney. (Birds, raccoons, and other animals may build nests inside chimneys when they are not used frequently.)
Examine the mortar between the bricks to make sure that it is in good condition, and is not cracked or flaking away. Also check the flashing where the chimney meets the roof. Make sure that there is a watertight seal around the flashing (Image 2). If the seal is damaged or cracked, it can be patched with caulk.