Water Heating Systems Flashcards
6 cards from real 306A practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Water Heating Systems flashcards as text
What is the purpose of a recirculation pump on a domestic hot water system?
Answer: To maintain hot water circulation in the piping so that hot water is available quickly at distant fixtures
A recirculation pump circulates hot water through the distribution piping and back to the heater, keeping the pipes warm so that hot water is available almost instantly at remote fixtures without wasting water while waiting.
What is a 'point-of-use' water heater?
Answer: A small, dedicated water heater installed near a single fixture or group of fixtures to reduce wait time for hot water
A point-of-use water heater is a compact unit installed close to a specific fixture (such as a remote bathroom or kitchen sink) to provide immediate hot water without long pipe runs, reducing wait time and water waste.
What is the maximum temperature setting for a water heater in a dwelling with small children?
Answer: 49°C at the faucet outlet
Water delivered to fixtures in homes with small children should not exceed 49°C (120°F) at the outlet. While the heater may store water at 60°C for Legionella control, a mixing valve must temper it to 49°C or lower for safe delivery.
What is the advantage of an indirect water heater connected to a boiler?
Answer: It uses the boiler's high-efficiency heat exchanger to heat domestic water, achieving greater efficiency and faster recovery than a standalone unit
An indirect water heater uses the boiler's already-efficient combustion system to heat domestic water through a heat exchanger coil inside an insulated storage tank. This leverages the boiler's high efficiency (often 90%+) for water heating.
Why must the T&P relief valve discharge pipe have no valves, restrictions, or reductions in size?
Answer: Because any restriction could prevent the valve from discharging at its rated capacity during an emergency, leading to tank failure
The T&P discharge pipe must be unrestricted to ensure the relief valve can discharge at its full rated capacity during an overpressure or overtemperature event. Any valve, reducer, or restriction could impede flow and lead to catastrophic tank failure.
What is the primary cause of water heater tank failure?
Answer: Internal corrosion due to anode rod depletion and sediment accumulation
The most common cause of tank failure is internal corrosion. Once the sacrificial anode rod is consumed, the tank lining begins to corrode. Sediment accumulation accelerates this process by trapping heat and creating hot spots on the tank bottom.