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The Inside Outside Guys: All about water heaters

Ken Calverley and Chuck Breidenstein
Special to The Detroit News

In days gone by, hot water in a home was a luxury used for cooking and the once a month bath that saw the entire family use the same water. Dad first, then mom, then the kids, until it might be so dirty the fear was you might “throw the baby out with the bathwater.”

Today, hot water is a convenience we take for granted. It is available throughout the home at several “points of use” (POU), from bathrooms to laundry rooms, kitchens and more. But how we heat and distribute the water through the home requires decisions based on lifestyle, convenience, cost and energy efficiency.

Tank style water heaters are still the most popular type of unit. The “knock” on them is an issue called “stand-by loss” which describes the fact that a tank heater continually heats a volume of water to desired temperatures, then the heat is “lost” to the surrounding air and the unit must re-heat the same water so it will be hot when you need it.

In tankless water heaters, water is heated right away as it passes through the unit so you don’t run out.

The alternative is a “demand” water heater that does not have a tank, but only heats water when it is needed. These work almost instantaneously so, when properly sized, they might provide a continuous supply of hot water. The “knock” on these is higher initial cost and the need for pure water to avoid mineral build up inside the unit. There are also hybrid demand systems with small tanks attached.

A common misconception regarding demand units is that you will have hot water at the POU as soon as you turn on the faucet. This might be true of the small electric unit under the sink for coffee, but for larger volumes you will still have what we call “cold water sandwiching,” that pipe full of cold water between the water heater and the POU that must be run down the drain before we get heated water at the faucet.

To have “instant” hot water at POU, you can either install smaller units at the POU, or what we call an active loop powered by a small pump that keeps hot water at a designated POU 24/7.

Water quality can be an issue and, truth be told, most domestic water has some contaminants and suspended minerals in it. That “pop” you may hear when the tank unit is heating is from expanding water trapped in the mineral build up on the bottom of your tank. A new tank unit will have a “sacrificial anode”; a replaceable metal rod in the tank that gives itself up to the minerals to keep them from settling on the tank walls and damaging the unit. This can degrade over time and must be replaced.

A demand unit may require good water filtration and periodic maintenance to assure proper function over time.

Water heaters can be purchased in various efficiencies with some exceeding 90%. That means for every $1 of fuel you purchase for the unit, more than 90% of that fuel will be converted to heat energy for heating the water rather than simply going up the chimney as exhaust.

Volume requirements are also a consideration. Each tank unit has a rated “Recovery Rate” that indicates how quickly the unit can re-heat water as it is being used. This is calculated using 70% of a tank’s capacity. The faster the recovery, the quicker you can take your shower after the kids have had theirs.

High efficiency units will require powered exhaust with a higher initial cost. Lower efficiency units can be retrofitted to existing chimneys, though installation of a new chimney liner may be required by code.

Should you insulate hot water pipes? “Yes”, according to the Energy Information Administration. Closed cell foam insulation is available for any DIY insulation application and is effective. It is also recommended to insulate the cold water line into the water heater for about 6 lineal feet.

Is there a “one size fits all solution” for water heating? According to Dave Greylen from Waterwork Plumbing, “every home and family has different needs, so we like to customize water heating solutions for each home, each family.”

For more home improvement advice listen to the Inside Outside Guys every Saturday and Sunday on News/Talk 760, WJR-AM, from 10 a.m. to noon or contact us at insideoutsideguys.com with your questions.