24 Questions
What is the purpose of a pressure or altitude gauge on a hot water heating boiler?
To monitor the level of water in the boiler
Why is a siphon not required between the gauge and the boiler in hot water service?
Because hot water boilers are completely filled with water
Which fitting is required by ASME BPVC IV on every hot water heating boiler to prevent overheating?
Temperature controls
What is the function of low water fuel cut-offs on hot water heating boilers?
To prevent the boiler from operating when the water level is too low
What is the minimum hydrostatic test pressure required for a tank designed for a working pressure of 200 kPa?
520 kPa
What is a good practice for installing isolation and drain valves in the piping to a bladder-style expansion tank?
It allows for replacing the expansion tank without draining the heating system
What is the purpose of an air separator connected to an expansion tank in a hot water heating system?
To direct air bubbles into the tank
Why do non-bladder style expansion tanks pose a risk of corrosion in heating systems?
They introduce oxygen into the water
What is the main benefit of bladder-style and nitrogen-charged expansion tanks?
They eliminate the risk of corrosion
What is placed in the connecting line between an expansion tank and the hot water supply header to allow for draining the tank without draining the system?
A shutoff valve
In what section is expansion tank operation and maintenance extensively covered?
Part B, Unit 4, Chapter 3 Operational Checks
What is a requirement for expansion tanks designed for systems operating above 200 kPa?
They must be designed and constructed in accordance with ASME BPVC VIII, Division 1
What do 'altitude' gauges in hot water systems indicate?
System fullness
What is the purpose of the second pointer in 'altitude' gauges?
To manually adjust the gauge
In closed hot water heating systems, what should the pressure be in relation to altitude?
Greater than altitude
What are tridicator gauges commonly used for?
Indicating temperature and pressure
Where should the thermometer or temperature sensor be located in hot water heating boilers?
At or near boiler outlet
What is the minimum reading for the thermometer used in hot water heating boilers?
20°C
What is the maximum reading for the thermometer used in hot water heating boilers?
205°C
At or below what pressure should the automatic reseating type safety relief valve relieve for a hot water heating boiler?
MAWP
For boilers exceeding $400kPa$, what is the maximum pressure setting for additional safety relief valves?
$5%$ above MAWP
Where should stop valves be placed on hot water heating boilers?
In supply and return pipe connections
What is the purpose of expansion tanks in hot water systems?
Preventing excessive pressure buildup
In which type of systems can closed expansion tanks be used?
High operating temperatures and pressures
Study Notes
- "Altitude" gauges in hot water systems are pressure gauges calibrated in terms of height of water, indicating system fullness.
- Gauges have two pointers: one operated by bourdon tube assembly, and another manually placed.
- In closed hot water heating systems, pressure should always be greater than altitude.
- Pressure and temperature gauges are commonly combined into single gauges, known as tridicator gauges.
- Hot water heating boilers must have a thermometer or temperature sensor, indicating temperature at or near boiler outlet.
- Thermometers must have a minimum reading of 20°C and a maximum reading of 160-205°C.
- Each hot water heating boiler must have at least one automatic reseating type safety relief valve, set to relieve at or below MAWP.
- Additional safety relief valves may be set to higher than MAWP, but not more than 40kPa for boilers up to 400kPa, or 5% for boilers exceeding 400kPa.
- Stop valves must be placed in supply and return pipe connections on all hot water heating boilers, allowing for drainage without emptying the entire system.
- Expansion tanks provide storage space for excess water due to expansion, preventing excessive pressure buildup.
- Closed expansion tanks can be used in systems with high operating temperatures and pressures, and are connected to supply main or top of boiler.
- An expansion tank must be installed that will be consistent with the volume and capacity of the system.
Test your knowledge of the code requirements for fittings on hot water heating boilers according to ASME BPVC IV. Learn about the required fittings and their significance in ensuring the safe and efficient operation of hot water heating boilers.
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