Unit 21. Heating Boilers Flashcards
What are the two basic types of heating boilers
Low pressure steam boilers and hot water boilers
Heating service uses what type of boiler
Fire tube
Three reasons why industrial type water tube boilers are seldom selected for low pressure heating plants
Higher cost, closer supervision required, better water treatment requirements
List the advantages of a water tube boiler having serpentine shaped tubes
Efficient heat transfer, tube design eliminates expansion and contraction stresses, easy replacement of tubes
List the three main structural configurations for water tube boilers
A type, o type,and d type
A popular boiler used in residential and commercial hot water heating systems
Copper tubular boiler
Two types of cast iron sectional boilers
Horizontal and vertical
Short steel pipe sections machined to a taper on both sides and fitted into adjacent sections
Push nipples
List the advantages of cast iron sectional boilers
High resistance to corrosion, ease of assembly, choice of assembly location, possibility of enlarging boiler
To be classified as a low pressure steam heating boiler, the operating pressure must not exceed
103kPa
To be classed as a hot water heating boiler,the op temp of the water must not exceed
121 C and 160 kPa operating pressure.
Three methods of oil gun atomization
Air or steam (low pressure); mechanical ( high pressure); centrifugal
Which fittings are required on a hot water boiler.
Thermometer, safety relief valve, blow off or drain valve.
In hot water heating boiler systems, the gauge glasses are normally fitted to
Expansion tanks
For the scale on the steam gauge of a heating boiler, the travel of the pointer from 0-200kPa shall be at least
75mm
An essential fitting between the boiler and steam pressure gauge
A siphon
A solenoid type gas fuel valve
Is held closed by the fuel pressure
At what pressure should a hot water heating boiler operate if the relief valve is set to 750kPa
562 kPa. (750 - .25%)
What are required on all oil storage vessels
Air vents
Scales on a pressure gauge for a steam heating boiler shall be graduated between
200 -414 kPa
A relief valve is placed on the discharge of a fuel oil pump
So burner design pressure is not exceeded
Oil storage systems must be installed according to
NFA code, local bylaws and codes, CSA 139
What fitting is required in the feed water line adjacent to the boiler before the stop valve
A check valve
When a closed tube expansion tank on a hot water boiler is completely filled with water and the water in the system is raised in temp so that it expands, the result will be that
The pressure build up opens the safety relief valve
The working medium in a dead weight tester is
Medium weight oil
The most important rule in safe operation of a steam heating boiler is
Keep the water level in the boiler at a proper level
When starting up a cold heating boiler, if it is fired too fast damage can be caused by
Uneven expansion, thermal shock
The feed water pipe, before entering the boiler, must contain
A check valve and stop valve
As far as boiler capacity is concerned, the mechanical designer has two choices
Use 1 or 2 large boilers; connecting multiple smaller boilers in parallel
A gradual increase in stack temp is an indication of
Unclean heating surfaces
Auto fill valve on a hot water heating boiler
Operates in accordance with system pressure
Boiler blowdown piping must be
Full size to the point of discharge
The part of an air atomizing burner that imparts a turning motion to oil is the
Swirler
The combustion chamber of a serpentine tube water tube boiler is
Located below the tubes
On low pressure steam boilers, the boiler outlet valves are usually of what type
Gate valves due to their low resistance to flow
Rust in the gauge glass is an indication that
Corrosion of internals
Maximum operating temperature of a hot water boiler is
121 C
Air atomizing burner utilizes air pressure of approximately
100 kPa
For a relief valve pop test, boilers operating above 414 kPa are allowed +/-
5%
For hot water boilers operating up to 414kPa, a pressure relief valve opening pressure variation may be as much as
20 kPa
A steam boiler is blown down to
Discharge sediment and scale forming solids from the boiler
Explain how the oil flow to a modulating pressure atomizing atomizing oil burner is regulated
A constant supply of oil is pumped to the burner, to maintain the oil pressure in the burner nozzle,but a return passage allows some of the oil to be bled off and returned to the fuel tank. A control valve in the return line regulates the return oil flow and therefore the flow of the oil to the furnace
Two methods of lighting oil burners on packaged boilers using electric ignition
Electrode ignition, spark plug ignition
Define “puff back “ associated with delayed ignition
Weak ignition, improper adjustment of the electrodes,poor insulation may cause delayed ignition resulting in a puff back. A puff back is caused by a larger than normal amount of combustible mixture in the furnace which, when ignited, builds up a momentarily high pressure and blows back into the boiler room
List the minimum information that must be stamped on a boiler fitting
Manufacturer or trademark, service designation, material designation
Code requirements for steam heating boilers regarding minimum and maximum safety valve seat
Must not be smaller than 1/2” (12.7mm) or larger than 41/2” (110mm)
