Generally, hardwood floors need to be buffed every 3–5 years. The process usually takes about one day. Buffing refers to the process of using a stand up floor buffer. The floor is abraded with 180 grit screen on the buffer. This allows for the new coat of finish to mechanically adhere to the floor. This process works with great results as long as the floor hasn't had any waxes or synthetic cleaners. Denver Hardwood Floors
If your floor has noticeable scratches throughout, your best option is to sand down the floor and refinish it. A complete sanding removes scratches, but beware: This only works on real wood floors, not bamboo. If you have an engineered wood floor with a real wood surface, make sure the real wood surface is more than 1mm thick—sanding usually takes at least this much wood off the surface, so a thicker layer is required for a complete sanding. Hardwood Floors

Engineered wood flooring was created to lower the cost of wood flooring and attempt to fix some of solid wood’s shortcomings. It’s constructed from inexpensive plywood or particle board and topped with a thin veneer of hardwood. This construction helps with installation flexibility and slightly improves indent performance, but it adds a new set of problems as well. Because the “real” wood part of the floor is just a thin veneer, damage from scratches can be irreparable. Engineered wood floors are still made from porous wood, meaning they can’t be subjected to water.
Because tongue-and-groove boards are locked in place, removal involves cutting out the middle of each damaged board. The easiest way is to bore a 1-in.-dia. hole through both ends of each damaged board (photo 1). Then use a circular saw to connect the two holes (photo 2). Follow these steps to safely make the plunge cuts you need to repair your hardwood floors: 1. Adjust the depth of cut to the thickness of the floorboards. Plug in the saw and put on eye protection. 2. Pull back the retractable blade guard with your thumb. Then hold the nose of the baseplate on the floorboard and lift up the rear of the saw. 3. Align the blade with the right edge of one of the holes. Make sure the blade isn't touching the floor, then squeeze the trigger and slowly lower the spinning blade into the board. 4. Grip the saw firmly with both hands and guide it in a straight line until you cut into the right edge of the hole at the opposite end of the board. 5. Move back to the first hole, align the blade with the left edge and cut to the left edge of the second hole. Pry out the middle section with a hammer and chisel. Chop out the remaining edges, being careful not to damage any surrounding boards (photo 3). The "tongue" piece will be nailed in place, so break it out in small pieces. Then pull out the nails with a hammer or locking pliers. The existing floorboards have a tongue and groove milled on each end and along the edges. Chop off the tongue exposed by the board you just removed so you can slip in the new board (photo 4).
Choose your replacement hardwood flooring. You don't have to replace your old floor with the exact same wood or flooring type that you just removed! You can glue your new hardwood flooring into place if you like. You can also install nail-down, floating (or locking) hardwood flooring as a replacement. The choice is up to you and what your budget allows. Denver Hardwood Floor Install

Awesome explanation! When I say heat pump to people, it's amazing how often their eyes glaze over...even though most of them have had refrigerators and air-conditioners their whole lives and have never asked themselves how they work. Same principle! Compressor and expansion valve (and the heat-holding capacity of a phase change; another confusing one for people). thanks for helping educate! Hardwood Floors