Boiler Test One

Question 1

Low Temp Boilers

Answer 1

Max temperature 250 F (120C)
Max pressure 160 psig (1100 Kpa)
With cast Iron heat exchanger (High mass 30 Psig)
Typically rated in BTU/hr or EDR
Usually Net rated

Question 2

BTU

Answer 2

British Thermal Unit
amount of heat required to raise temp of 1 lb of water 1 F

Question 3

BHP

Answer 3

Boiler horse power

Question 4

High temp Boilers

Answer 4

Over 250 F (120C)
Rated in MBH or BHP
Gross rated
ASME 1

Question 5

MBH

Answer 5

One thousand BTU’s British thermal units per hour

Question 6

One BHP

Answer 6

The ability of a boiler to evaporate 34.5 pounds of water per hour

Question 7

Input rating

Answer 7

Represents the amount of heat in the fuel that is burned by the burner

Question 8

Output rating

Answer 8

represents the total heat output of the boiler, available as hot water

Question 9

Net Rating

Answer 9

75% of the gross rating - losses - stack, system or pipe - Difference between net and gross is a deduction intended to cover typical installation losses

Question 10

Caloric Value

Answer 10

Potential energy in gasses

Question 11

One EDR of Hot water

Answer 11

150 BTU

Question 12

One EDR of Steam

Answer 12

240 BTU

Question 13

Gross Output

Answer 13

Total heat output of boiler available as steam or hot water

Question 14

Low Mass Boiler

Answer 14

• Need to have fluid moving though tubes when burner is on
• Code states a flow switch must be added to, or can be installed alone instead of LWCO
• Commonly Copper, Aluminum or Stainless steel all of which are non- corrosive and resilient

Question 15

High Mass Boilers

Answer 15

-Need to be Full of water when the burner is on
- Minimum code is LWCO (Float or Probe type)
-Cast Iron

Question 16

If you drop the pressure on a liquid it becomes a

Answer 16

Gas

Question 17

Efficiency =

Answer 17

Efficiency% = Gross output in BTU/ Input in BTU X 100

Question 18

Condensing boilers

Answer 18

• Efficiency rate of 90%
  -Achieved by cooling products of combustion to water vapor (steam) in flu then reverting to liquid water and water providing 970 BTU/lb of condensate
  Latent heat energy is added to typical sensible heat of a mid efficient (83-85%) providing 90% efficiency

Question 19

Considerations for Condensing Boilers

Answer 19

• High operating temperatures (above 140 F at exchanger inlet) may not allow water vapor to condense - reducing efficiencey
  -Flu gasses have cooled and are no longer rising with convection so now a fan or direct vent system is needed
  -Condensate is acidic & should be neutralized prior to disposal in the sanitary system

Question 20

Conventional VS Condensing Boilers

Answer 20

Conventional - Need to leave heat behind in the flue gas so the gas is hot enough to rise up and out of venting system (convection)
Condensing - cools the flue gasses to condensation point and gains latent heat energy

Question 21

Hot water Boiler Operator turns the Boiler on & off in response to regular heat demands, 3 types:

Answer 21

Microprocessor
Liquid sensing bulb fluid temperature control
Thermostat

Question 22

Boiler Control: High Limit

Answer 22

Shuts Boilers fuel if the boiler gets to hot
- The temperature is set above the operating temperature range but never higher than the manufacturer states
- ASME states never higher than 250F

Question 23

Code requires two temp controls for any boiler

Answer 23

1) Operating control
2) High limit

Question 24

ABSA requires large boilers to have a manual reset

Answer 24

Manual reset has a small red button between 2 wires if it trips the boiler must be manually restored by pressing button

Question 25

Safety Relief Valve (SRV)

Answer 25

- Last line of defence against over pressure and or explosion - stem must be vertical - must be officially approved - No valves between heat source and discharge - Discharge must grade and drain away from valve with no reduction in size - No lower than 6" and no higher than 12" from floor

Question 26

Air Removal Devices

Answer 26

Air vent - Manual or automatic Air separation devices - Boiler fitting, Line scoop, Microbubble resorber

Question 27

Manual Air vents

Answer 27

Located at piping high point to release trapped air from the piping

Question 28

Automatic Air vent

Answer 28

Server same purpose as manual but must consider: 1) Include isolation valve for servicing 2) Pressure at highest point must be minimum of 4 psi to prevent air entrainment (sucking in )

Question 29

Boiler fitting

Answer 29

Attaches directly to the HIGH MASS BOILER outlet nozzle & releases air from inside the boiler & allows water out to system

Question 30

Line Scoop

Answer 30

The fitting increases in diameter to allow the fluid to slow and release air bubbles - min of 5 pipe diameters of straight pipe needed at inlet and outlet to smooth flow out - if a cushion type expansion tank is used, the air scoop is piped to this tank which is installed above the boiler

Question 31

Micro Bubbler Resorber

Answer 31

- uses a screen like media inside for bubbles to attach to when they accumulate the fitting has a built in air vent that releases the gas - they have no inlet outlet turbulence issues like the line scoop

Question 32

Fluid Expansion

Answer 32

From filling to operating temperatures, water volume can be charged up to 5% so we have 3 types of containers or expansion tanks 1) open expansion Tank 2) cushion Tank 3) Diaphragm Tank

Question 33

Open Expansion tank

Answer 33

Open tank must be placed at least 3' above the highest pipe because it is open to the atmosphere where water boils at 212 F these systems are limited to 180F

Question 34

Cushion Tank

Answer 34

The Cushion tank is located in the boiler room above the boiler the air scoop is piped to the cushion tank equal amounts of water return to the system - similar to an open expansion tank except it does not have a vent to atmosphere - it is closed under pressure 15 psi is typical for residential

Question 35

Diaphragm Tank

Answer 35

Diaphragm tanks have rubber bladder between air and fluid - they are pre charged, pressure must be charged to match system - because there is a bladder separating, The Air scoop now has an auto air vent instead of pipe to tank - can be located anywhere around boiler -often best in high temp/ low pressure location

Question 36

2 Types of centrifugal pups are used in hydronic systems

Answer 36

Conventional and Wet Rotor Circulator

Question 37

Conventional Circulator (big red silver tip)

Answer 37

Air cooled lubricated by oil and grease

Question 38

Wet Rotor Circulator (Grundfos)

Answer 38

Cooled and lubricated by the heating system fluid

Question 39

In the pump there is an impeller and a Volute

Answer 39

Impeller - is a disc used by both style pumps to move water or direct the flow of a moving fluid Volute - spiral shaped pump casing with the purpose to convert liquids velocity to pressure as the impeller discharges the liquid through the casing nozzle

Question 40

4 types of piping systems

Answer 40

1)Series or perimeter loops 2)Mono flow or one pipe system 3)Two pipe direct return 4)Two pipe reverse return

Question 41

Series or perimeter loops

Answer 41

- a loop can only be one zone - limited capacity 50 000 to 60 000 btu/hr - heat emitters form part of piping - water cools as it moves through circuit heaters near end have lower output

Question 42

Mono Flow or one pipe system

Answer 42

- heaters can be zoned separately -special venturi tees required on return -fluid speeding through venturi nozzle draws fluid from side branch this moves heating fluid through the heater

Question 43

Two pipe Direct

Answer 43

- "First supplied, first returned" prone to short circuits balancing valves on return are a must

Question 44

Two pipe reverse return

Answer 44

-Most Balanced arrangement - each heat emitter has equal piping lengths