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HIP Magazine – Summer Issue 2016- Answer Sheet

PAGE 44

Identify the parts

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Name the component or pipe identification A 6 Bar pressure relief B Composite valve C Pressure gauge central heating D 3bar pressure relief valve for the heating E Expansion vessel for the domestic hot water F Temperature and pressure relief G Cold feed to showers H Connection for hot water secondary return I Manual air vent J Central heating zone valve K D1 pipe L Central heating flow M Differential by-pass N Tundish O Central heating flow P Filling loop Q Combined cylinder and high limit thermostat R D2 pipe S Primary flow from boiler T Zone valve for hot water

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Keeping the dinner warm

The above photo is a cooker burner, taken out and mounted for demonstration.

What component is labelled A?

Flame supervision device

What component is labelled B?

Ignition electrode

A

B

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What component is this?

Gas by-pass

If the flame remains on low during initial light up and does not go to high flame, what is the most likely cause?

Flame supervision device faulty, damaged phial, Phial not in flame

Every time the oven reaches temperature the burner flame extinguishes, what is the most likely fault?

By-pass blocked, prevent burner remaining on low flame when reached temperature

When servicing a cooker you discover one of the hot plate burner is showing signs of incomplete combustion, would you

o Inform the customer and tell them not to use that particular hot plate ring.

o Inform the customer and with their permission, disconnect the appliance and issue an ID.

o Inform the customer and with their permission, isolate the appliance and issue an AR.

o Don’t worry about it, it’s not caused any harm before.

You have been asked to install an oven in a room of 8m3, there is a door to outside fitted in the same room, do you need ventilation?

o Yes o No

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Hot water and supply systems

G3 Hot water supply and systems Sizing of copper discharges pipe D2 for common temperature relief valve

outlet sizes Valve outlet size

Minimum size of discharge pipe D1

Minimum size of discharge pipe D2 from tundish

Maximum resistance allowed, expressed as a length of straight pipe (ie no elbows or bends)

Resistance created by each elbow or bend

G 1/2

15mm 22mm 28mm 35mm

Up to 9m Up to 18m Up to 27m

0.8m 1.0m 1.4m

G3/4 22mm 28mm 35mm 42mm

Up to 9m Up to 18m Up to 27m

1.0m 1.4m 1.7m

G1 28mm 35mm 42mm 54mm

Up to 9m Up to 18m Up to 27m

1.4m 1.7m 2.3m

The above table is based on copper tube Answer the question below based on the table above:

1. The length of D2 pipework required from the G1/2 outlet valve is 6m; there are 4 bends on the pipe, what size D2 pipe do you use?

Answer 6m pipe + 4x 0.8 resistance of bends= 3.2m 6m+3.2m= 9.2m 22mm will only be sufficient up to 9m therefore 28mm D2 pipe will be required

2. You have been asked to check if the existing D2 pipe meets the G3 regulations. From the G1 valve outlet a 22mm pipe has been installed to a tundish. From the tundish the pipe runs to outside and terminates pointing down 95mm from the ground and is protected with a guard. The D2 pipe is 22mm and is 4m long with 5 bends. Explain your answer.

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Answer D1, 22mm is less than the minimum size required for a G1 valve outlet size

3. From a G1/2 valve outlet a 28mm D2 pipe discharges outside, the pipe run is 6m in length and consists of 4 bends is this installation acceptable?

Answer Yes

4. Calculate the D2 pipe size required for an installation consisting of a G1/2 pressure relief valve 12m of pipe with 4 bends

Answer 12m pipe 4x1m (bend resistance) =4m 4+12=16m total pipe length, a 28mm D2 pipe would be required

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Test your knowledge with the unvented test

Name the 3 building regulations un-vented hot water cylinders are subject to?

• G3 of the building regulations • Part L • Water supply(water fittings) regulation 1999

When linking an unvented boiler to a heat sources, which fuel should not be used?

o Electricity o Gas o Oil o Solid fuel

When choosing or replacing an immersion heater for an unvented cylinder it must comply to BS EN 60335-2-73 and contain a;

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o Bi metallic strip o User thermostat and non-resetting thermal cut out (G3 3.29) o User thermostat and self-resetting thermal cut out o Night switch for economy 7

An unvented storage cylinder must never exceed what temperature

o 60 degrees o 85 degrees o 100 degrees o 95 degrees o

The discharge pipe D1 should be;

o At least the same size as the temperature relief valve (G3 3.51)

o One size larger than the temperature relief valve o One size less than the temperature relief valve o The same size as D2 pipe

The maximum length of pipe pipe between the temperature/pressure relief and the tundish is;

o 500mm o 300mm o 600mm (G3 3.54) o 700mm

The vertical section of pipe below a tundish before any bend or elbow should be

o 500mm o 600mm o 300mm G3 3.56 o 1000mm

D2 pipe should have a continuous fall of at least;

o 1 in 300 o 1 in 200 G3 3.56 b o 1 in 500 o 1 in 20

Where a single common discharge pipe serves more than one system it should be at least

o The same size as the largest D2 pipe o One size larger than the largest D2 pipe G3 3.59 o You cannot have a common discharge pipe o Two sizes larger than the largest discharge pipe

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When connecting a discharge pipe to a soil stack, the branch must have;

o An independent branch pipe to the soil stack G3 3.60 o You can use the same branch pipe from another sanitary appliance o You can fit the D2 pipe to a washing machine stand pipe o Only metal pipes can be used

Termination of the discharge pipe needs to be considered to prevent risk to persons in the vicinity; an appropriate discharge point would be;

o A trapped gully with the end of the pipe below a fixed grating and above the water seal

o Downward facing low level discharge 100mm above ground with a wire cage or guard to prevent contact

o A high level discharge into a metal hopper and metal down pipe. o All the above G3 3.62

To prevent scalding the hot supply to a bath should be limited by a blending valve to a maximum temperature of:

o 44 degrees o 43 degrees o 48 degrees G3 3.65 o 60 degrees

When commission is carried out by a person registered with a competent person scheme he must give notice to the Building Control Bodies (BCB) within

o 7 days o 10 days o 30 days G3 3.78 o 3 months

What is the recommended cold water pipe size for an unvented cylinder?

o 22mm o 35mm o 15mm o 28mm

What is the recommended minimum flow rate required for an unvented cylinder?

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o 10 litres per minute o 15 litres per minute o 20 litres per minute o 25 litres per minute

What is the resistance created by a 22mm elbow on a discharge pipe D2 in metres?

o 0.5m o 0.8m G3 Table 1 o 1m o 1.5m

Water discharges continually from the expansion relief valve every time the cylinder is heated, what could be the possible cause?

o Faulty expansion relief valve o Faulty temperature relief valve o Faulty pressure reducing valve o Faulty Expansion vessel

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Page 52 Waste pipe dilemmas

What is the maximum length of a 32mm unventilated branch pipe you can install?

1.7m Diagram 3 Document H of the building regulations

How many appliances can you connect to a 32mm branch pipe?

3 appliances, Table 2 Document H of the building regulations

What is the minimum depth of trap seal on a wash hand basin connected to a primary ventilated stack?

75mm Table 1 Document H of the building regulations

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What type of traps are installed on the wash hand basins above?

Bottle traps

If a bath or shower waste is discharged directly into a gully, what measurement in millimetres can the trap seal be reduced too?

38mm, Table 1 additional information, Document H building regulations.

On a two store property what is the minimum distance the lowest branch can be from the invert of the drain.

o 300mm o 500mm o 450mm (Diagram 2 Doc H) o 1000mm

The gradient on a 32mm pipe is 40mm per metre, what is the maximum distance you can install this pipe without ventilation.

o 1.7m o 1.1m (Table 2 Doc H) o 0.7m o 2m

The minimum radius of the bend at the foot of the stack should be

o 200mm (1.26 Doc H) o 100mm o 150mm o 250mm

Ventilating pipes within 3m of an openable window should terminate a minimum of how high above the window?

o 600mm o 1000mm o 900mm (Diagram 6 Doc H) o 300mm