Phase 2 Assessment Flashcards
What is 0 Kelvin (absolute zero)?
-273 degrees celsius
How much does air weigh?
1.29 kg/m3
What is 100 celsius in Kelvin and Fahrenheit?
373K and 212 Fahrenheit
What is 0 celsius in Kelvin and Fahrenheit?
273 K and 32 Fahrenheit
What is -100 celsius in Kelvin and Fahrenheit?
173K and -148 Fahrenheit
What is -200 celsius in Kelvin and Fahrenheit?
73K and -328 Fahrenheit
What is -273 celsius in Kelvin and Fahrenheit?
0 K and -460 Fahrenheit
How much steam is made from 1 litre of water? (m3)
1600
What is sublimation?
When ice is heated so quicly it goes from solid to gas
What happens to the boiling point of water if the pressure increase?
It increases
What is latent heat?
Energy required to change the state of a substance
What is sensible heat?
Energy required to change the temperature of a substance
What is conduction?
Heat is pulled from high to low temperature
What is convection?
Hotter molecules rise when they are heater and more dense materials sink
What is radiation?
Heat is transferred from one body to another via infrared
What is the equation for thermal conductivity?
area x difference in temperature
What is the equation for heat conductivity?
thermal conductivity x U value x temperature difference
What is power?
the rate at which work is done
What is the specific heat capacity of water?
4.18 J/kg/degrees celcius
What is the equation for volume which includes pi?
pi x radius2
What is the equation for flow rate?
area of the pipe x velocity of the liquid
What is direct current?
Only goes one way like those in a battery
What is alternating current?
Goes back and forth like those in a mains supply
What is a valance electron?
Can be lost or gained
What is the definition for amps?
rate that electricity flows through an appliance
What is the definition of power?
the rate at which electric energy is converted into other forms of energy
What is ohms law?
electric current is directly proportional to voltage and inversely proportional to resistance.
What is the equation for voltage?
Current x resistance
What is the equation for power?
Current x voltage
What are the 3 types of earthing supplies?
TN-S(Terra neutral seperate)
TN-C-S(Terra neutral combined)
TT(Terra terra)
How do you work out circuit total resistance?
(1/R1) + (1/R2) + (1/R3)
What is 1 bar in Psi?
15 Psi
What is the maximum flow possible by sucking on the mains?
12 Litres per minute
What are the 3 types of water conditioners?
Electrolytic, Electromagnetic, Magnetic
What are the 6 types of water filters?
- Activated carbon filter
- Ion exchange
- Sediment filter
- Reverse osmosis
-Distillation - Disinfection
What are 3 advantages of a direct cold water system?
- Cheaper to install
- Mains pressure
- Drinking water at all outlets
What are 3 disadvantages of a direct cold water system?
- No water reserve
- Condensation on pipework
- Greater ware on fittings
What are 3 advantages of an indirect cold water system?
- Reserve of water
- Chance of backflow is reduced
- Lower chanve of leaks on fittings
What are 3 disadvantages of an indirect cold water system?
- Increased cost of the installation
- Lower pressure at outlets
- Risk of frost damage in the loft
What is a solenoid valve?
Electro-mechanical device, which controls the flow of water into the cistern
What is a transducers?
senses fluctations in pressure and activates or cuts out the pumps
What is the maximum chase depth of brick or block wall?
vertical- 1/3 of depth
Horizontal- 1/6 of the depth
What makes a hot water cylinder direct?
An immersion heater is used to heat the water inside
What makes a hot water cylinder indirect?
The boiler heats water that passes through a coil within the cylinder which heats the water inside indirectly
How is a thermal store heated?
Mains water passes through a heat exchanger which is enclosed in a storage cylinder
What height should the vent pipe be above the water level in the cistern?
150mm + 40mm for every metre of height in the system
What are 3 positives for an open vented hot water system?
- store of water
- low installation cost
- low noise level
What are 3 negaitives for an open vented hot water system?
- space needed for storing water
-risk of freezing - low pressure system
What are 3 positives for an unvented hot water system?
- High pressure + flow
- Balanced pressure at all outlets
- No cw storage needed
What are 3 negatives for an unvented hot water system?
- High installation cost
- High system noise
- No store of CW
What are the 6 types of showers?
- Digital, mixer valve, pumped, bath shower mixer, gravity, cistern fed
What are the 3 classes of cylinders and their pressure capabilities?
Class 1 - 3.6 bar or 25m of head
Class 2- 2.2 bar or 15m of head
Class 3- 1.5 bar or 10m of head
How does a thermal store work?
Cylinder is filled with primary water and mains water is fed through a coil within the cylinder
What is the coefficient of linear expansion for PPP?
0.00018 per metre per degrees celsius
What is the coefficient of linear expansion for copper?
0.000016 per metre per degrees celsius
How much does water expand by when it freezes?
10%
What to consider before installing an unvented cylinder?
- Available pressure and flow
- Route of discharge pipework, termination and pipe sizes
- type of terminal fittings
-cost
How long does the hot water draw off pipe need to be (horizontally)?
Min 450mm
At what temperature does the temperature relief valve kick in?
90-95 degrees celcius
What are the 4 types of float valves (BS1212)?
1- Portsmouth & Croydon
2- Brass Diaphragm type
3- Plastic diaphragm
4- Cistern float valves
What is backflow?
Flowing of water in the wrong direction due to loss of pressure in the system
What is the purpose of a single check valve?
Protect category 1 water from category 2
What is the purpose of a double check valve?
Protects category 1 water from 2&3
What is an AUK1 air gap for?
Wc airgap
What is an AUK2 air gap for?
Bath and washand basin
What is an AUK3 air gap for?
Kitchen sink & bidet
What is AA backflow prevention?
Air gap with unrestricted discharge above the spillover level
What is AB backflow prevention?
Air gap with a weir overflow (dental surgery)
What is AD backflow prevention?
Air gap with a jump jet (washing machine)
What is BSEN806 to do with?
Design installation, testing and maintenance of hot and cold water system
What is BS8000 to do with?
Requirements for good workmanship within hot and cold water systems
What is hydronic heating?
When water is used to transport heat throughout the building
What is the purpose of a low loss header?
enables hydraulic separation by providing a separation point between the primary and secondary circuit, or multiple circuits
What are some positives of a reverse return system?
Reduces the need for balancing
- used with S+Y plans
- compliant with building regs part L
What are some negatives of a reverse return system?
- more expensive and difficult to install
- Careful planning required
What are the required pipe distances betweem underfloor heating loops?
150-225mm
What are typical temperatures for underfloor heating? (Concrete and timber floor)
Concrete= 40-45 degrees Celsius
Timber= 50-60 degrees Celsius
What are the advantages of warm air heating?
- quick heat up times
-no need for fuel supply - reduced maintenance cost
What are the disadvantages of warm air heating?
- Heat unit and duct work is unsightly
- Large space required
Spreads bacteria & dust
What are the advantages of district heating?
- Reduced CO2
- No need for fuel supply
- Helps th gov reach green targets
What is the disadvantage of district heating?
If the control plant fails all properties are affected
What are storage heaters?
Electric heaters that heat up internal ceramic bricks during the night and release during the day
What are the advantages of storage heaters?
-Simple installation
-Safe & quiet
- ideal for no fuel supply
What are the disadvantages of storage heaters?
-Electricity is more expensive
- Excess heat is wasted
- difficult to control comfortable conditions
What are the 4 components for a boiler plus installation (combi)?
-Load compensation
-Smart control
- Flue gas heat recovery
- Weather compensation
How do you calculate current (VIR)?
Divide voltage by resistance
How do you calculate current (PIE)?
Power divided by potential difference
What are some components of a boiler interlock?
Cylinder stat, room stat, motorised valve, boiler stat, flow switch, air pressure switch
What are the 5 types of boilers?
-Traditional (non-condensing)
- System boiler
- Combi boiler
- Freestanding
- Wall mounted
What are the 4 types of flues for boilers?
- Room sealed
- Flue less
- Open flue
- Fan-assisted
What are the advantages of a traditional boiler?
-Long lasting
- Very robust
What are the disadvantages of a traditional boiler?
-Heavy
- Noisy
- Not efficient
- Non compliant with part L
What are the advantages of a condensing boiler?
-Compliant with part L
- High efficiency
-High flow rate for Hot water
- Low noise pollution
What are the disadvantages of a condensing boiler?
- High maintenance
- Possible to freezing
- Placement of condensing pipe could be difficult
What are the advantages of a combi boiler?
- Compact size
- Efficient
- Instantaneous hot water
-Cheap installation
What are the disadvantages of a combi boiler?
- Bad flow rate at multiple outlets
- No water reserve
- Difficult to work
What is a compartment?
Enclosure specifically designed to house a gas appliance
What is the correct fall for a condensate pipe?
45mm per metre away from the boiler
What are the 3 grades of copper?
R290- Hard copper
R250- Half-hard copper
R220- Soft (microbore)
What are the 3 grades of LCS, colour and use?
- Heavy-Red-Steam fire
- Medium-Bue-Heating & Oil
- Light-Brown-Gas
What are the 6 stages of filling and venting a Central heating system?
1- Soundness
2- Cold flush
3- Cleanse system
4- Hot flush
5- Fill the system
6- Check the system
Installing an air Seperator allows for the coupling of what two pipes?
Cold feed and vent connections
What is atmospheric pressure at sea level?
1.01 bar