Module 10 Appliance Burner Pressures and Gas Rates Flashcards
In plain English what does Regulation 29 say?
Do anything to an appliance measure operating pressure and/or gas rate
Which module covers burner pressure?
Module 10
Which module covers gas rates?
Module 10
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
b) Installer gives them to responsible person
Name two places that you can find the burner pressure for an appliance
1) MI
2) Data plate
Attached image of a data plate
1) what is the mid range burner pressure?
2) Measured when the appliance is hot or cold?
1) 9.9 mbar
2) Hot
If the burner pressure cannot be found / obtained then you cannot comply with regulation 29. What should you do?
1) Poor performance = ID
2) Performance OK but can’t be checked = sub standard, deal with it! (NCS or AR)
Where is the burner pressure test point usually located?
On outlet side of multi-functional valve
The pressure test point located on the supply side of a multi-functional valve measures what?
Appliance supply pressure – should be circa 20 mbar
If the burner pressure is wrong and an appliance cannot be adjusted what can you assume and test?
Issue with supply pressure
Likely causes of excessive burner pressure
1) Faulty meter governor. Check working pressure at meter
2) If meter governor is faulty turn off gas supply and contact ESP
Why is excessive burner pressure an issue?
a) Incomplete combustion
b) Appliance overheating
c) Flue system unable to deal with extra products of combustion
Likely causes for low burner pressure
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
Describe what a range rate appliance is and how it should be set up.
Output of appliance adjusted to suit heating demand.
Set by adjusting burner pressure
Pressure falls outside of range – issue!
Where would you find a modulating burner?
Combination boiler – water full gas rate, heating range rated.
Often burner pressure not adjustable!
What is the link between the gas rate and the burner pressure?
Gas rate is determined by the calorific value of the gas, burner pressure and size of the injector
Why measure gas rate?
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!
MI / Data badges usually do not contain gas rates. What other piece of information can we use instead?
Rated input (kW)
How do you measure gas rate on a U6 type meter?
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
How do you measure gas rate on a G4 meter?
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
An E6 meter has an LCD with three sets of units. Which set is used to measure gas rates?
The middle set
The first set is used for billing
The last number (6) is the rated meter capacity
How do you convert kW to BTUs?
a) kW x 38.6
b) kW x 3,412
c) kW x 3,600
b) kW x 3,412
What is a BTU?
British Thermal Unit
How to do you calculate Heat input?
Gas Rate x Calorific Vale = MJ/hr
Heat Input is calcluated in MJ/hr
The bolier is rated in kW
How do you convert from one to the other?
MJ/hr / 3.6
A domestic gas fire - the meter takes 3 minutes to pass one cubic foot. What is the gas rate for this appliance?
3600 / 180 = 20
20 x 0.028 = 0.56m3/hr
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
a) 1.53m3/hr
Why?
R2 - R1 = 0.051m3 per 2 minutes
Therefore 0.051m3 x 30 = 1.53m3 per hour
If the gas rate is 0.56m3/hr what is the heat input for the appliance?
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
a) 2.24kW
The gas rate test determines the gas volume being burned at the appliance burner.
True of False?
True
U6 meter - one revolution of the dial = what volume?
1ft3
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
b) 10 minutes
What type of meter is shown in the picture?
G4
If the gas rate is out vs the data plate how do you determine whether you are over or under-gassed?
(E6 & G4 meters)
3600 = seconds in 1hr
m3 = volume of gas
10.76 = factor for natural gas
n = number of seconds until next digit apprears
What is being measured at each point
