Module 10 Appliance Burner Pressures and Gas Rates

Question 1

In plain English what does Regulation 29 say?

Answer 1

Do anything to an appliance measure operating pressure and/or gas rate

Question 2

Which module covers burner pressure?

Answer 2

Module 10

Question 3

Which module covers gas rates?

Answer 3

Module 10

Question 4

Under Regulation 29 what must happen to the instructions for a new appliance:

a) Installer keeps them
b) Installer gives them to responsible person
c) They get thrown away

Answer 4

b) Installer gives them to responsible person

Question 5

Name two places that you can find the burner pressure for an appliance

Answer 5

1) MI
2) Data plate

Question 6

Attached image of a data plate

1) what is the mid range burner pressure?
2) Measured when the appliance is hot or cold?

Answer 6

1) 9.9 mbar
2) Hot

Question 7

If the burner pressure cannot be found / obtained then you cannot comply with regulation 29. What should you do?

Answer 7

1) Poor performance = ID
2) Performance OK but can’t be checked = sub standard, deal with it! (NCS or AR)

Question 8

Where is the burner pressure test point usually located?

Answer 8

On outlet side of multi-functional valve

Question 9

The pressure test point located on the supply side of a multi-functional valve measures what?

Answer 9

Appliance supply pressure – should be circa 20 mbar

Question 10

If the burner pressure is wrong and an appliance cannot be adjusted what can you assume and test?

Answer 10

Issue with supply pressure

Question 11

Likely causes of excessive burner pressure

Answer 11

1) Faulty meter governor. Check working pressure at meter
2) If meter governor is faulty turn off gas supply and contact ESP

Question 12

Why is excessive burner pressure an issue?

Answer 12

a) Incomplete combustion
b) Appliance overheating
c) Flue system unable to deal with extra products of combustion

Question 13

Likely causes for low burner pressure

Answer 13

a) Faulty meter governor
b) Pipe sizing too small – test by turning more appliances on and see if pressure drops
c) Partial blockage of pipe work – check pressure at each appliance and work out if common pipe or individual
d) Damaged pipework - trace and repair

Question 14

Describe what a range rate appliance is and how it should be set up.

Answer 14

Output of appliance adjusted to suit heating demand.
Set by adjusting burner pressure
Pressure falls outside of range – issue!

Question 15

Where would you find a modulating burner?

Answer 15

Combination boiler – water full gas rate, heating range rated.

Often burner pressure not adjustable!

Question 16

What is the link between the gas rate and the burner pressure?

Answer 16

Gas rate is determined by the calorific value of the gas, burner pressure and size of the injector

Question 17

Why measure gas rate?

Answer 17

Burner pressure won’t tell you if the appliance has the correct heat input. Why? Big injector, more gas, small injector, less gas, both same burner pressure!

Question 18

MI / Data badges usually do not contain gas rates. What other piece of information can we use instead?

Answer 18

Rated input (kW)

Question 19

How do you measure gas rate on a U6 type meter?

Answer 19

Time one complete revolution of the meter test dial

3600/secs for 1 revolution x 0.028 (converts it to metric) = m3/hr

(m3/hr x 38.6)/3.6 = Gross kW

Gross kW/1.1 = net kW

Question 20

How do you measure gas rate on a G4 meter?

Answer 20

Note meter reading, run appliance for two minutes, take second reading.

The maths:

(R2-R1) x 30 = m3/hr

(m3/hr x 38.6)/3.6 = Gross kW

Gross kW/1.1 = net kW

Question 21

An E6 meter has an LCD with three sets of units. Which set is used to measure gas rates?

Answer 21

The middle set
The first set is used for billing
The last number (6) is the rated meter capacity

Question 22

How do you convert kW to BTUs?

a) kW x 38.6
b) kW x 3,412
c) kW x 3,600

Answer 22

b) kW x 3,412

Question 23

What is a BTU?

Answer 23

British Thermal Unit

Question 24

How to do you calculate Heat input?

Answer 24

Gas Rate x Calorific Vale = MJ/hr

Question 25

Heat Input is calcluated in MJ/hr

The bolier is rated in kW

How do you convert from one to the other?

Answer 25

MJ/hr / 3.6

Question 26

A domestic gas fire - the meter takes 3 minutes to pass one cubic foot. What is the gas rate for this appliance?

Answer 26

3600 / 180 = 20

20 x 0.028 = 0.56m³/hr

Question 27

Gas rate using a G4 meter

Reading 1 (R1) = 00796.425

Reading 2 (R2) = 00796.476

What is the gas rate:

a) 1.53m³/hr
b) 59.05m³/hr
c) 16.41m³/hr
d) 14.91m³/hr

Answer 27

a) 1.53m3/hr

Why?

R2 - R1 = 0.051m³ per 2 minutes

Therefore 0.051m³ x 30 = 1.53m³ per hour

Question 28

If the gas rate is 0.56m³/hr what is the heat input for the appliance?

Answer 28

Question 29

A boiler is turned on and the meter test dial takes 45 seconds to pass 1ft³. What is the heat input in kW?

a) 2.24kW
b) 86.46kW
c) 24.02kW
d) 21.83kW

Answer 29

a) 2.24kW

Question 30

The gas rate test determines the gas volume being burned at the appliance burner.

True of False?

Answer 30

True

Question 31

U6 meter - one revolution of the dial = what volume?

Answer 31

1ft³

Question 32

Gas Rates

Hwo long should you leave an appliance on for to warm up?

a) 5 minutes
b) 10 minutes
c) 15 minutes
d) Any of the above

Answer 32

b) 10 minutes

Question 33

What type of meter is shown in the picture?

Answer 33

G4

Question 34

If the gas rate is out vs the data plate how do you determine whether you are over or under-gassed?

(E6 & G4 meters)

Answer 34

3600 = seconds in 1hr

m3 = volume of gas

10.76 = factor for natural gas

n = number of seconds until next digit apprears

Question 35

What is being measured at each point

Answer 35