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42 AUGUST 2016 | FUEL OIL NEWS | www.fueloilnews.com BY GEORGE LANTHIER HVAC/ HYDRONICS THE PRODUCTION OF DOMESTIC HOT WATER is impor- tant in controlling the spread of disease in humans and animals. DHW is essential today in residential, commercial and industrial applications, in not only the preparation of foodstuffs, but also as a key element of most local, state and national health codes. In this article, we will discuss the ongoing controversies and rising liability related to risks of scalding and bacterial growth. Before you can thoroughly discuss and understand "scalding," you must first learn that in the world of the product and installa- tion liability attorney there is no such thing as "common sense." In that world, the manufacturer and installer must ensure a safe installation regardless of the various uses that the domestic water system and heating system could be exposed to, and how the end user will be affected. Therefore, although we may agree with many of you that feel scalding is mostly preventable by the end user, we will approach it from a technical standpoint as though it were not. This section was specifically prepared in regards to the pre- vention of scalding of humans and domestic animals within the confines of the Commonwealth of Massachusetts where the author lives. Outside the Commonwealth, it should be used only as a guideline since local and state codes in your jurisdiction have precedent over those included here and vary from jurisdiction to jurisdiction. However, it is agreed that Massachusetts's code is neither the toughest nor the easiest in the United States. Our goal is to cover the heating of water by the use of any water heater, range boiler, vessel or boiler front (internal tankless), or container used for supplying hot water for domestic, culinary or sanitary purposes. It should be noted at the outset that there are many known methods and techniques used by the plumbing and heating trades to reduce the output of scalding temperatures from domestic hot water heaters. It should also be noted that many of these methods are not used by many tradesmen due to high initial cost, installation costs, and operating and service maintenance costs and time, as well as customer preference. That does not mean that these methods and devices do not work. It simply means that those methods tend to be ignored, for cost reasons. It should also be mentioned that any of these solutions are less expensive than one hour of a liability attorney's time. More importantly, the Gas Appliance Manufacturers Association's Water Heater division states that "more than 4,000 children are scalded by tap water every year" and that is from electric, gas and oil-fired equipment. The installation, repair and servicing of any hot water heaters by persons who do not hold the appropriate licenses is not only illegal, but may also be dangerous due to those inadequately trained personnel. Those who are unfamiliar with any state's plumbing and sanitary codes should not work on or about DHW heaters. The most effective way to prevent the scalding of humans and most domesticated animals is the use of an anti-scalding valve. Period. In many applications such as hospitals and nurs- ing homes these valves, and other requirements, are mandated under local plumbing codes and state building codes. Although most state codes require that a domestic hot water heater be tested, it is important to note the parameters of these tests. For example, the Massachusetts codes stipulate that: in no case can a domestic water heater be allowed to operate with a temperature in excess of 212° F; and in no case shall a tankless heater be allowed to operate with a temperature in excess of 180° F. The codes state that to comply, a temperature/pressure relief valve (T&P) should be installed on storage tank type water heaters, and a pressure relief valve should be installed on tankless heaters. In addition, we also found these other requirements: When supplying a shower of any kind, you cannot exceed a maximum temperature of 112° F at the showerhead. The Sanitary Code states that "the domestic hot water shall be a minimum of 110° F and a maximum of 130° F." The Massachusetts plumbing code also states that the fol- lowing temperatures are considered the maximum allowed for hospital applications: "125° F for fixtures, 180° F for kitch- ens, and 180° F for laundry." This is important to note since the Commonwealth defines a hospital as "any facility for the care of the sick." This means nursing homes, rest homes and charitable homes for the aged, and rehabilitation centers. Does it also mean private homes designated specifically for use by the handicapped? We don't know, but we wouldn't bet against it! The first consideration to providing the proper supply of safe hot water that will satisfy the requirements of the user is that at a higher boiler-water temperature, smaller equipment may be used. Then again, if you are to provide adequate hot water at lower boiler-water temperatures, larger equipment must be used. Essentially the basic rule for hot water production must be observed: storage or recovery. If the decision is made to go with lower temperatures, the effect of those lowered tem- peratures on the heat emission rate of the heating system must be examined. If the combination DHW-heating system was designed for 180° F water and the temperature is lowered, will the system heat the house? Keep in mind that lowering the water temperature in any storage tank type system may lead to the formation and growth of bacterial bodies including those linked to Legionnaire's Disease. This will not happen with a domestic hot water system that uses a tankless only. With the tankless heater system, there is no tank, so all of the water is drawn and passed through the coil during a draw. Proper sizing of equipment is essential. Sizing must be done Health Issues & Domestic Hot Water