Kitchen appliances offered by most major manufacturers come in sizes that can be considered reasonably standard. But be warned: Standard size or not, they may not fit your existing opening, gas line or the available electric outlet.

Before you depart on your appliance selection journey, it is extremely important to size things up first – literally.

You will need to make measurements and take several important notes. We strongly recommend that you completely remove each and every appliance selected for replacement. This will allow you to fully inspect the place where the appliance resides so that you can record where and what water, gas and electrical supply lines exist, and you can accurately measure the height, width and depth of the cabinet opening.

A common problem with an electric range occurs when the 220-volt wall plug prevents the range from being pushed all the way back against the wall. Most appliances make allowances for plug protrusion by building a recess into the back of the unit. But, the appliance manufacturers haven’t gotten together to decide on exactly where this important recess should be located.

Another example: There is absolutely no standard when it comes to gas line connections for gas cooktops. How critical can this be? In one case we had to eliminate an adjacent drawer in order to install the selected appliance.

Appliances also have a tendency to remain in place for great lengths of time – anywhere from 10 and 20 years or more would not be unusual. Over such periods, things can change.

When a new floor or countertop is installed, for example, an opening size can get smaller. In time, electric circuit size requirements can change and even the depth of a cabinet can have a direct bearing on installation.

There may be several other unforeseeable conditions that you would not notice with the appliance in place.

If you’ve ever worked on your home, you know that there is no such thing as a perfectly square, horizontal, level or plumb opening. Houses shift, and as the house shifts, so do the cabinets. As cabinets shift, so do the appliances they hold.

Where an old dishwasher may look great in its existing opening, a brand new appliance may look terrible. With the appliance out of the opening you can use a square and a level to check the floor, sides and top. This gives you the lead time needed to make needed adjustments long before the new appliance arrives.

When you are considering a new appliance, there is more to think about than how it looks and how much it costs. The electrical service size and location, the gas service size and location, the cabinet opening size as wells as the opening depth will all have some bearing on installation and on the ultimate cost – or savings – to you.

In studying tankless water heaters, for example, we discovered in the installation manual that we needed a three-quarter-inch gas line connection. After a phone conversation with a knowledgeable friend in that business, we found that even though a three-quarter-inch connection was needed, a one-inch supply line was required to provide enough volume.

Finally, don’t have the expectation that your new appliance will work perfectly once installed. People who make the appliances make mistakes. Instead, be sure that the seller is someone who can service it promptly and professionally with local help.

Purchasing a kitchen appliance from a big box appliance store who advises you that all repairs and service will have to be made by the manufacturer could leave you without a stove or refrigerator for who knows how long. This is a situation that may not be worth the perceived savings.

For more home improvement tips and information from James and Morris Carey, go to their Web site at www.onthehouse.com or call 800-737-2474 Saturdays from 6 to 10 a.m. The Careys are also on KRKO (1380-AM) from 6 to 8 a.m. every Saturday.