Module 4.1 Knowledge Questions

Question 1

Name three classification of ventilation

Answer 1

1) Adventitious
2) Additional
3) Compartment

Question 2

What are the purposes of the components indicated?

Answer 2

Storm guard - stops rain being blown in

Baffle - stops wind noise and drafts

Cavity duct - nothing blocks the ventilator

Question 3

The pipe used in the vent shown is a 105mm in diameter. Is it suitable for use with a 15kW (net) appliance?

NB Area of a circle is πR²

Answer 3

Yes!

Free area of pipe =

(22/7) x (10.5/2)² = 86.62cm²

Boiler requirements =

15kW - 7 = 8kW x 5cm² = 40cm²

QED pipe ok

Question 4

Name 3 materials a vent grill can be made of

Answer 4

1) Terracotta
2) Rigid plastic e.g. ABS
3) Metal e.g. Aluminium

Question 5

When inspection or installing a ventilator what 6 points should be checked?

Answer 5

1) Is the free area adequate for the appliance(s) it serves?
2) Is the ventilator of the correct type?
3) Is the vent sleeved across the cavity?
4) Is the ventilator of the hit and miss type?
5) Is the ventilator fitted with a fly screen?
6) Is the ventilator being installed in the correct place?

Question 6

What three types of vent are not suitable?

Answer 6

1) Those fitted with fly screens
2) Hit and Miss types
3) Terracotta types should be carefully checked for actual permanent area

Question 7

If you have a single O/F appliance in a room what is the calculation for calculating air vent size?

Answer 7

1) Gross kW / 1.1 = net kW

Less 7kW (adventitious air)

x 5cm² = free are required

Question 8

Name two reasons to ventilate a compartment

Answer 8

1) O/F - combustion and cooling
2) R/S - cooling

Question 9

When an air vent is installed on the inside wall of a property, the vent must be sited:

a Not less than 450mm from floor level,
b Not more than 450mm from floor level.
c Not more than 450mm from ceiling level.
d Not less than 450mm from ceiling level.

Answer 9

b Not more than 450mm from floor level.

Question 10

The ventilation requirement for open flued appliances is dependant upon:

a Heat input.
b Heat output.
c Room dimensions.
d Flue height.

Answer 10

a Heat input.

Question 11

What action should the gas operative take it an air vent, of adequate size but fitted with a fly screen, is encountered?

a Install another air vent of the same size with a fly screen.
b With the users permission remove the fly screen.
c Leave the vent and instruct the user to clean regularly.
d Disconnect the appliance and label.

Answer 11

b With the users permission remove the fly screen.

Question 12

An open flued combination boiler with hot water input of 36kW (net) and heating input of 21kW(net) is fitted within a kitchen measuring 2.5m by 2.2m by 1 .8m. What is the vent free area required?

a 70cm².
b 130.5cm².
c 145cm².
d 180cm².

Answer 12

c 145cm².

Question 13

A tumble dryer with an input of 5kW (net) is fitted in the kitchen measuring 2.5m by 2.2m by 1 .8m. An openable window is needed, but what is the additional vent free area required?

a 35cm².
b 50cm².
c 100cm².
d No vent is required.

Answer 13

c 100cm².

Why?

100cm² if room volume is less than 3.7m³ per kW

i.e. Is the room less than 3.7 x 5kW = 18.5m³?

Question 14

If an open flued combination boiler with hot water input of 36kW (net) and heating input of 21kW(net) and a tumble dryer with an input of 5kW (net) were fitted in a kitchen, measuring 2.5m by 2.2m by 1 .8m, what is the vent free area, in addition to the openable window, required?

a 100cm².
b 145cm².
c 245cm².
d 290cm².

Answer 14

b 145cm².

The two appliances fall into different categories so you take the largest of the two values (Module 4, page 9)

Question 15

A room sealed boiler with a range rated burner from 16kW to 21kW (net) is fitted in a compartment and set at 18.5kW (net). What are the required vents to direct outside?

a 51.75cm2 both top and bottom.
b 70cm2 both top and bottom.
c 92.5cm2 both top and bottom.
d 105cm2 both top and bottom.

Answer 15

d 105cm2 both top and bottom.

Question 16

A room sealed combination boiler with hot water input of 33kW (gross) and heating input of 25kW (gross) is fitted in a kitchen measuring 2.5m by 2.2m by 1.8m. What is the vent free area required?

a 117cm2.
b 113.6cm2.
c 120cm2.
d No vent required.

Answer 16

d No vent required.

Question 17

A gas fire and back boiler of inputs 7kW (gross) and 16kW (gross) respectively has recently been fitted in a bedsitting room. What is the ventilation requirement?

a 37cm2.
b 68.6cm2
c 120cm2.
d Installation not allowed.

Answer 17

d Installation not allowed.

Question 18

The purpose of the top vent installed within a compartment is to:

a Assist the pull of the flue.
b Supply air for combustion.
c Remove warm air for cooling.
d Reduce the pull of the flue.

Answer 18

c Remove warm air for cooling.

Question 19

An open flued boiler with input of 24kW is fitted in compartment and vented to a room. What are the ventilation requirements? (Remember the data badge does not state net)

a T 120cm² / B 120cm² / Room 120cm²
b T 240cm² / B 480cm² / Room 85cm²
c T 218cm² / B 218cm² / Room 74cm²
d T 218cm² / B 436cm² / Room 74cm²

Answer 19

d T 218cm2 / B 436cm2 / Room 74cm2

Remember, compartment can’t have adventitious but the room can!

Question 20

In addition to one decorative fuel effect gas appliance, a room contains a gas cooker and one opened-flued instantaneous water heater of 25kW heat input. The room volume is 30m³ and the manufacturers instructions for the DFE gas appliance specify that 100cm² of purpose provided ventilation is required for this appliance. What is the overall ventilation for the room?

a 125cm².
b 25cm².
c 325cm².
d 225cm².

Answer 20

d 225cm².

DFE = 100cm², cooker = 0cm², O/F = 25kW x 5cm² = 125cm². DFE takes adventitious since it is a fixed rate

Question 21

In addition to one decorative fuel effect gas appliance, a through-room contains the following appliances:

An opened flued central heating boiler (21 kW heat input)
One open-flued gas fire (5 kW heat input)
One gas cooker
One open-flued water heater (15.5 kW heat input)
The room volume is 100m³ and the manufacturers instructions specify that 100cm² of purpose provided ventilation is required for the decorative fuel effect gas appliance. What is the overall ventilation for the through-room?

a 195cm².
b 95cm².
c 295cm².
d 225cm².

Answer 21

a 195cm².

Why?

Through-room = DFE + greatest of:

1) Total flueless = 0
2) O/F space heaters (21+5)-7 x5 = 95
3) Water heater (15.5-7)x5 = 42.5

If there are two DFEs not adventitious can be used

Question 22

Oil and solid fuel burning appliances installed in a room or internal space (in additional to gas burning appliances) shall?

a Have no effect whatsoever on the ventilation requirements for the gas installation.
b Be treated as if they were gas appliances of similar type and rated input.
c Be disconnected and a “Do Not Use” label attached.
d Only require an openable window.

Answer 22

b Be treated as if they were gas appliances of similar type and rated input.

Question 23

What are the possible effects of double glazing, cavity wall insulation and draught proofing on ventilation provision?
a lt will result in an Immediate Dangerous installation.
b It will have no effect whatsoever.
c lt may restrict the Adventitious ventilation.
d lt will require the removal of the double glazing, cavity wall insulation and draught probing.

Answer 23

c lt may restrict the Adventitious ventilation.