college work

[midsguy]

hi all
im doing a college course & need a few answers if any one can help please ?
When Natural gas is completely burned what are the two main constituents of the products of combustion?
When checking the polarity on a central heating system from an existing spur the approximate reading should be?
What would you look for if you had severe flame lift on a new installation?
What component would you check if you had fan run but no ignition?
thanks for any information given
paul

 

[bazdaman]

CH4 + 2 O2 -> CO2 + 2 H2O that is carbon dioxide and water vapour

Dont know if i understand 2nd one correctly, L-N 240v L-E 240v and N-E 0-15v

I would first check gas pressures.

Air pressure switch

 

[midsguy]

also need another answer please
. Where it is necessary to turn off the isolating cock and disconnect a union to make a repair, what are the minimum safety requirements to be carried out ?
thanks
paul

 

[gregers]

yep i agree

fair play for asking,but shouldnt you be researching for the info rather then getting someone to answer them?

 

[midsguy]

yep i agree

fair play for asking,but shouldnt you be researching for the info rather then getting someone to answer them?

ive done loads research just checking to see if ive the correct answers mate before submitting, no harm in getting a second opinion of an expert is there ?

 

[bazdaman]

Lets just see how many arguments you will cause over your last question!

I agree with greggers you need to research properly or it wont stick your city and guilds course book or whatever course book you use will have all these answer plus explanations why there is a lot of help on here but under pinning knowledge is what you need!
What college year are you in

 

[bazdaman]

Fair point, but if researched correctly you wouldnt need answers checking

 

[midsguy]

Fair point, but if researched correctly you wouldnt need answers checking

dont mean to offend any one or cause any arguments just want to double check if ive found the correct answers ?

 

[gregers]

then maybe you shouldve posted your findings 1st and then got the experts to concur your results or point out any errors that may be there.

 

[midsguy]

then maybe you shouldve posted your findings 1st and then got the experts to concur your results or point out any errors that may be there.

yes perhaps your right but never thought of that one, sorry
the only 1 i dont really understand is
Where it is necessary to turn off the isolating cock and disconnect a union to make a repair, what are the minimum safety requirements to be carried out? i would say temp earth bonding if on pipework but believe this is on a boiler ? so i would say leak detector when repaired & possibly a tightness test ?

 

[bazdaman]

I didnt mean ur question regarding working after an ISO valve was out of order, i just think it will get two different answers and theres only one right one!

 

[midsguy]

I didnt mean ur question regarding working after an ISO valve was out of order, i just think it will get two different answers and theres only one right one!

yes i understand what your saying but i dont completely understand that question, thats why i dont know the correct answer /

 

[gregers]

then maybe you shouldve posted your findings 1st and then got the experts to concur your results or point out any errors that may be there.

yes perhaps your right but never thought of that one, sorry
the only 1 i dont really understand is
Where it is necessary to turn off the isolating cock and disconnect a union to make a repair, what are the minimum safety requirements to be carried out? i would say temp earth bonding if on pipework but believe this is on a boiler ? so i would say leak detector when repaired & possibly a tightness test ?

its all french/german etc to me m8,

but ive been a chippy for a number of years now and would expect any trade you end up in for you to show a bit of common by asking the correct way,that way there will be an abundance of help given to you by the experts on this forum.
remember you might not have the correct answer but by showing your workings you will still achieve a mark for them.
good luck.

 

[PrenticeBoyofDerry]

When checking the polarity on a central heating system from an existing spur the approximate reading should be?

They would be the same as checking polarity on almost any single phase circuit.
In the UK, Europe has decided that our nominal voltage is 230V BS7671 (wiring regs) allow for 10% + or - that value.
So when testing for live polarity, by the use of a voltage indicator you would expect reading of:
Line-Neutral to be 230V (+/- 10%)
Line-Earth to be 230V (+/- 10%)
Neutral-Earth to be 0V

If you were confirming polarity using dead tests, then this would be done by continuity tests in ohms.