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Heating > Boiler Test One > Flashcards

Boiler Test One Flashcards

1
Q

Low Temp Boilers

A

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

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2
Q

BTU

A

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

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3
Q

BHP

A

Boiler horse power

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4
Q

High temp Boilers

A

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

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5
Q

MBH

A

One thousand BTU’s British thermal units per hour

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6
Q

One BHP

A

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

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7
Q

Input rating

A

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

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8
Q

Output rating

A

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

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9
Q

Net Rating

A

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

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10
Q

Caloric Value

A

Potential energy in gasses

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11
Q

One EDR of Hot water

A

150 BTU

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12
Q

One EDR of Steam

A

240 BTU

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13
Q

Gross Output

A

Total heat output of boiler available as steam or hot water

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14
Q

Low Mass Boiler

A
  • 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
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15
Q

High Mass Boilers

A

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

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16
Q

If you drop the pressure on a liquid it becomes a

A

Gas

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17
Q

Efficiency =

A

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

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18
Q

Condensing boilers

A
  • 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
19
Q

Considerations for Condensing Boilers

A
  • 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
20
Q

Conventional VS Condensing Boilers

A

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

21
Q

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

A

Microprocessor
Liquid sensing bulb fluid temperature control
Thermostat

22
Q

Boiler Control: High Limit

A

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

23
Q

Code requires two temp controls for any boiler

A

1) Operating control
2) High limit

24
Q

ABSA requires large boilers to have a manual reset

A

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

25
Q

Safety Relief Valve (SRV)

A
  • 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
26
Q

Air Removal Devices

A

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

27
Q

Manual Air vents

A

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

28
Q

Automatic Air vent

A

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 )

29
Q

Boiler fitting

A

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

30
Q

Line Scoop

A

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

31
Q

Micro Bubbler Resorber

A
  • 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
32
Q

Fluid Expansion

A

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

33
Q

Open Expansion tank

A

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

34
Q

Cushion Tank

A

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

35
Q

Diaphragm Tank

A

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

36
Q

2 Types of centrifugal pups are used in hydronic systems

A

Conventional and Wet Rotor Circulator

37
Q

Conventional Circulator (big red silver tip)

A

Air cooled
lubricated by oil and grease

38
Q

Wet Rotor Circulator (Grundfos)

A

Cooled and lubricated by the heating system fluid

39
Q

In the pump there is an impeller and a Volute

A

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

40
Q

4 types of piping systems

A

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

41
Q

Series or perimeter loops

A
  • 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
42
Q

Mono Flow or one pipe system

A
  • 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
43
Q

Two pipe Direct

A
  • “First supplied, first returned”
    prone to short circuits
    balancing valves on return are a must
44
Q

Two pipe reverse return

A

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

Heating (1 decks)

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