A.O. Smith VB/VW- 1000, VB/VW- 750 instruction manual Water Temperature Regulation, Risk of Scalds

Water Temperature Regulation

HOT WATER CAN SCALD: Boilers are intended to produce hot water. Water heated to a temperature which will satisfy space heating, clothes washing, dish washing and other sanitizing needs can scald and permanently injure you upon contact. Some people are more likely to be permanently injured by hot water than oth- ers. These include the elderly, children, the infirm or physically/ mentally disabled. If anyone using hot water in your home fits into one of theses groups or if there is a local code or state law requiring a specific temperature water at the hot water tap, then you must take special precautions. In addition to using the lowest possible temperature setting that satisfies your hot water needs, a means such as a mixing valve should be used at the hot water taps used by these people or at the hot water supply tank. Mixing valves are available at plumbing supply or hardware stores. Fol- low the manufacturer’s instructions for installation of the valves. Before changing the thermostat setting on the hot water system controller, see Table 8.

Hot water temperatures required for automatic dishwasher and laundry use can cause scald burns resulting in serious personal injury and/or death. The temperature at which injury occurs varies with the person’s age and time of exposure. The slower response time of children, aged or disabled persons increases the hazards to them. Never allow small children to use a hot water tap, or to draw their own bath water. Never leave a child or disabled person unattended in a bathtub or shower.

The boiler should be located in an area that is inaccessible to the general public.

Never allow small children to use a hot water tap or to draw their own bath water. Never leave a child or handicapped person unat- tended in a bathtub or shower.

TABLE 8. Risk of Scalds.

Water Temperature	Time to Produce 2nd & 3rd Degree
	Burns on Adult Skin
Over 170°F (77°C)	Nearly instantaneous
160°F (71°C)	About 1/2 second
150°F (66°C)	About 1-1/2 seconds
140°F (60°C)	Less than 5 seconds
130°F (54°C)	About 30 seconds
120°F (49°C) or less	More than 5 minutes

SHOULD OVERHEATING OCCUR OR THE GAS SUPPLY FAIL TO SHUT OFF, TURN OFF THE MAIN MANUAL GAS SHUTOFF VALVE TO THE APPLIANCE.

The operating temperature of the boiler must be maintained as follows:

•120°F (49°C) or higher inlet water temperature to the boiler.

•20°F(11°C)differentialbetweentheboiler’sinletandoutlet(e.g.120°F [49°C] inlet, 140°F [60°C] outlet minimum design temperatures).

If the inlet water temperature into the boiler is less than 120°F (49°C), adjustments on the water bypass and the outlet valves at the rear of the boiler, see Figures 14 and 15, are required; wait at least one minute between adjustments for the temperature to stabilize.

1)If necessary, throttle down (close) the water outlet gate/ball valve until the desired outlet water temperature (120°F [49°C] minimum) is reached. Wait one minute.

2)Note the outlet and inlet temperature indicator readings.

a)If the inlet water temperature is less than 120°F (49°C), open, in small increments, the bypass (balancing) valve until the minimum 120°F (49°C) inlet water temperature or 20°F (11°C) differential, whichever has the higher inlet temperature, is attained.

b)If the inlet water temperature is greater than 120°F (49°C) and the 20°F (11°C) differential is not present, close the bypass valve until the 20°F (11°C) differential is attained.

NOTE: It may be necessary to make further adjustments on the outlet and bypass valves until the desired inlet and outlet water temperatures are reached.

MANIFOLD PRESSURE CONNECTIONS

Take the manifold pressure, refer to Table 1, by removing the pipe plug and inserting a suitable 1/8” NPT hose barb for connection to the manometer/pressure gauge. Upon completion of measurements and adjustments, remove the hose barb and replace the pipe plug. Check for gas leaks and insure all connections are gas tight, see Figure 19..

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