Home Improvement : Instant Hot Water Dispenser Vs. Microwave

QUESTION: We’re getting ready to remodel our kitchen and are thinking about installing an instant hot water dispenser for making coffee and tea. They’re very convenient, but how do they compare in cost and energy use to heating water in a microwave oven?

ANSWER: It depends on how you use it. If you make four or more cups (8 oz. size) a day, the instant hot water dispenser is probably the more efficient choice. Keep in mind it can also be used for soups, cereals, gelatins, gravies, peeling tomatoes and blanching vegetables. If you make fewer cups, then the microwave oven is more efficient. The difference in efficiency has to do with how they work.

The instant hot water dispenser uses an electric coil to heat the water to 160-190 degrees. The efficiency is 100% because the heat is transferred directly to the water. However, the heated water is then stored in a small tank (or thermos) so there is some heat lost during storage. Most instant hot water dispensers store about one third to one half gallon of water. The heat loss is small, but constant. So overall efficiency is less than 100%.

A microwave oven uses microwaves to heat the water. This is less efficient than the electric coil because electricity must be converted to microwaves, reducing efficiency to 50%. However, since no water is stored, there are no heat losses.

While nothing surpasses the convenience of an instant hot water dispenser, they can be a safety risk for small children. The water is hot enough to scald in less than a second. If you have small children, consider installing the dispenser well out of reach. Select the right size unit--smaller is better as long as it meets your hot water needs. It may be safe to add an insulating wrap as well. Check with the manufacturer first.

The electric plug-in tea kettle and “hot shot” hot water makers are the most efficient ways to boil water, if you heat only the amount needed. Unfortunately, most of the time they’re used to heat more water than needed. How many times have you seen a full kettle set to boil for only one cup of tea? All the efficient technology in the world won’t make up for poor use and inefficient habits. So use it wisely!

Sanding Wood Will Shave Off ‘Whiskers’

Q: A general contractor painted some new wooden bifold doors for me and it feels as if grains of sand had been added to the paint. The surface is very rough. What’s the problem? Shouldn’t a contractor be familiar with this?

A: The roughness you’re feeling is wood “whiskers.” It’s caused by the grain in the wood rising when the surface is wetted. Sanding before the prime coat and between additional layers of paint will “cut” those whiskers. It also provides a good mechanical bond between the wood surface and layers of paint.

It’s very important to take the time to sand the surface initially and between subsequent coats of paint. The best remedy for your bifold doors is to lightly sand them, then apply another coat of paint.

When sanding, match the coarseness of the paper to the size of the whiskers. Generally, fine grain sandpaper will be sufficient. If the whiskers are especially thick, a medium paper may be necessary for the first sanding.

Produced by the Energy Extension Service, a division of the Washington State Energy Office.