If you're considering an outdoor fireplace or firepit, one thing to consider is how much maintenance it involves. You don't want to spend all your summer evenings cleaning out the fireplace, right? A nice article over at the Green Living Journal offers some tips to help you select an outdoor fireplace. Their section on maintenance tells you which units will require the least amount of effort to keep clean and functional:
"Chain store and mass marketed fireplaces made out of copper, sheet steel, or clay, don't provide the safety or longevity of cast iron or cast aluminum. Below is a material list of currently manufactured outdoor fireplaces.
Clay chimineas can be babied, "Feed slowly, keep warm and dry.". But if you want a fireplace that is going to be safer and last longer, any other material on the market is a better investment. See Tip #6 for "Safety concerns with clay chimineas.".
Many home and garden outlets carry Sheet Metal outdoor fireplaces at a bargain cost. Cheap sheet metal fire pits are pretty much disposable items. Once they rust through their usefulness is gone. Be sure to check the gauge or thickness of the metal. Thin, mass marketed fireplaces may also melt if not thick enough. Enamel finishes disappear and exposed sheet metal will rust out quickly.
In some instances the body is cast iron but the neck or chimney is sheet steel. Eventually, you will be left with a cast iron fireplace body without a neck. Make sure the company carries replacement parts and find out the costs. If you will need to buy a new neck or other replacement parts frequently it's probably better to look elsewhere.
Cast Iron will rust if not maintained properly. The more cast iron you have to work with the longer it will last. Cast iron chimineas may also stain any surface the on which it is standing on if not maintained, so proper placement should be considered. If you decide to buy a cast iron chiminea make sure it is heavy and be prepared to maintain it.
Cast Iron may need a bit of maintenance but will last for years if looked after. Occasional painting with high temperature stove paint will halt rusting. Also, cast iron is extremely heavy and will withstand a lot of abuse. The Blue Rooster recommends cast iron chimineas for campground owners or places that they will be used without supervision. 200 pound chimineas tend not to "walk away".
There are no advantages of cast iron over cast aluminum except for a heavy weight. For most homeowners the added weight is a disadvantage.
Copper looks great out of the box and is a very safe material used for years in cooking utensils. Watch out for cast iron supports or bases that can rust shortly and stain your patio. Also, don't expect that shiny new copper fireplace to look like that after a fire or two. Green and rusty is usually the norm after its been used. If you don't mind the look of it, make sure it has a cover or rain lid and prepare to maintain the cast iron parts.
Some companies will drill holes in the bottom of the copper fire pits to let water (and ash) out when it rains so placement is important. Fire pits without drains can fill with water andmake a mess. If you do choose a copper fire pit or any fire pit for that matter, be sure it has a cover. Water and wind can make a mess of your ashes and/or embers.
If low maintenance and lifespan are priorities, Cast Aluminum is the best investment for your money. Aluminum chimineas are cast from the same molds as cast iron and look identical to cast iron. Cast aluminum outdoor fireplaces will not warp and have a melting temp only a few hundred degrees lower then cast iron. Cast aluminum alloy will not rust and is much lighter so it can be easily moved. Like a gas grill, cast aluminum has very little maintenance."
The whole article is quite a good resource and worth reading if you're in the market to buy:
Green Living Journal