It just takes a drop in the mercury and a little snow for many of us to evaluate our current heating system and if it fits our needs.

For others, it takes the bill at the end of a cold month like January to prove that it's not up to snuff.

Well, here are some things to consider when evaluating either a new or an auxiliary heating system.

First, think about what you need the new system for. Are you planning to upgrade or replace your current central heating system or do you just need some sort of auxiliary heat for especially cold days? Are you adding onto your house but the old system is too small?

Perhaps you're looking into something - like a gas fireplace - more for its ambience than its heating potential.

Regardless of your reason, it's good to keep that reason in mind as you gather information and make your final selection.

So what will the new system cost? Make sure you figure in not only installation cost, but also monthly fuel bills. A good installation company will measure your house, factor in any heat loss and determine the proper size of heat system you need.

But don't just talk to the salesman, also talk to friends or family who use the same kind of heating system to get an idea of its comfort, maintenance and expenses in a real home.

Remember, for some kinds of heating, a lot of the cost may depend on insulation and windows as well as where you live.

For instance, if you're way out in the county, there may not be a natural gas line nearby or it could cost a fortune to get it to you. Propane gas or oil systems are alternatives.

If you're thinking of a heat pump, your electrical supply system may need to be upgraded. The advice of heating technician or electrician and a PUD "feasibility study" are needed.

If you have access to free wood, a wood stove can be a very inexpensive way to heat your home.

But, while this type of heat is very comfortable, it requires chopping, splitting and stacking all that wood, plus constant tending. Then, there are the unwanted bugs that usually arrive with the wood and end up residing in your house.

You must also consider your family life and, of course, safety concerns. Toddlers, for example, can easily lose their balance and land on a very hot appliance. Or, perhaps you have a busy toddler who has a penchant for piling stuffed animals next to baseboard heaters.

Perhaps you've loved the dry heat of a wood stove, but are tiring of the mess and not sure you want to keep chopping wood the rest of your life.

Heating system changes are expensive and should suit your needs and the future needs of you and your house. Always keep in mind how the change will affect resale value.

These are the kinds of things you should consider.

In general, here are some of the pros and cons for different kinds of heating.

Pros

• Wonderful heat
• Sometimes inexpensive if you have a source of wood
• Great ambience

Cons

• Safety concerns with a hot stove
• Wood handling, curing, dry storage and infestation
• May soon be outlawed in populated areas due to air pollution
• Increased fire hazard
• Dirty
• Annual chimney inspection and cleaning

Pros

• Nice dry heat
• Fueling is easy
• No bugs

Cons

• Pellets are expensive
• Fuel storage
• Stove requires electricity to work
• Hot appliance concerns with toddlers

Pros

• Less expensive than other fuels
• Nice type of heat
• Clean burning
• A variety of types of appliances available

Cons

• Not available in all areas
• Annual maintenance required to avoid carbon monoxide concerns
• Complicated piping, ducting and venting may be required

Pros

• Least expensive electrical heating source
• Non-polluting
• Available in all areas

Cons

• Up-front expenses

• May require an electrical service upgrade in house
• Requires an air handler type furnace and ductwork
• Location of exterior unit may be an issue

Pro

• Inexpensive to buy
• Quiet
• Less maintenance and generally cleaner than other types of resistant heaters

Cons

• Least efficient type of electrical heat
• May require service panel upgrades or additional wiring
• As a potential fire hazard, the units reduce your effective room size
• Not child proof

Pros

• Inexpensive to buy
• Instant fan-forced heat
• More efficient than baseboards

Cons

• Subject to recall notices
• May require service upgrades or additional wiring
• Noisy and requires very regular cleaning of the coils and fan
• Attractive nuisance to toddlers
• As a potential fire hazard, the units reduce your effective room size