gas rate

[james the plumb]

Hey guys

got my gas inspection in a week and i still have probs with gas rates.
burner pressures piece of piddle but can anyone give me ( in laymans terms) any tricks of the trade .

 

[boilerman]

Sorry mate, I,m bad at explaining things like that,you need to get your books out.....and get it in your head......gas rates are quite important after all,but its one thing I,ve never been asked about.

 

[newbie1]

metric meter 3600x10.76xgas used in 2 min period then divide by no of seconds taken eg 121 then divide by 1.11 for nett kw

imperial meter 3600x1074 then divide by no of seconds for one rev of test dial then divide by 3412 then divide by 1.11 for nett kw

this is quite clear in your corgi book so cant see where you are struggling

 

[kirkgas]

if you are gas rating on an E6 meter, measure how much gas is used in 2 mins when you have the reading simply multiply this value by 321 this will give you applaince HI in Kw
eg first reading 1234,1234, second reading is 1234.2234, the difference (ie gas used is o.1m3) so 0.1 x 321= 32.1kw.
if using an old U6 meter, count how long it takes to complete 1 full rev of the test dial (ie how long it takes to burn 1ft3) divide this time into 1097, this will give you HI in Kw as well, eg it takes 58 seconds to burn ift3 of gas so 1097/58 = 18.91 kw
simples comparethegasrate.com

 

[diesel_ltd]

boiler on max rate

take first reading time for 2 min take second reading

take first away from second, times by 30 = gas rate

to covert to kw/h times gas rate by 10.65 kw/h gross /1.11 = net

 

[newbie1]

sorry guys these are the short cuts he may be asked to show his calculation

 

[Gr fto reborn]

The way I so it for a metric meter is
The diffence between two readings over 2 mins x 30 = meters cubed per hour

Meters cubed per hour x 10.72 = heat input of gas used in kw (gross).

Then just check it's within the 5% tolerance.

Imperial meter

3600 div by time taken for one revolution = ft cube of gas used per hour

Multiply that by 0.3 will give you the kw (gross)

 

[kirkgas]

sorry guys these are the short cuts he may be asked to show his calculation

newbie1 what you quoted were the "long" short cuts, what i gave were the real short cuts, he is getting a GSR inspection NOT an ACS exam, a short cut is perfectly acceptable, as gas rating with out the exact CV of the gas in your area is a guesstimate anyway.

James the plumb IF the inspector is a jobsworth and demands you quote the long method, tell him too **** off, i have always shown students the long method and the short cut and have always told them i would be delighted if they would use the short cut as that is better than a lot of gas engineers who dont do anything.
dont worry about the inspection IF you are good at what you do, the inspector will suss you out and if you are a bullsh1tter he will give you a hard time, if you are honest and open and have forgot something he will assist you. concentrate on 99.9% safety, IUP, regs etc check MI's and books if you dont know if correct dont guess anything, relax give yourself credit for what you now and the hard work you do on a daily basis,

 

[Billy Bob Bob]

i am with kirk on this one this is the way i was taught ignore the corgi book its bull crap use the formula kirk has shown you

 

[Toddyplumb]

Time it and look at the chart in your book (make sure its latest issue) If you cant remember how to do it. They have no option but to accept that !!!!

 

[kirkgas]

you have more chance looking at the wrong column in the book, or will make a mistake when you need to add 2 of the values together than using the short cut, write it at the top of the gas rate page in the book then you can find it in 2 secs if req'd
it is also very easy to insert a formula into a spreadsheet to work it out for you, i have one set up to show the students, set up properly you only need to insert either the gas used in 2 mins or time taken to burn 1 ft3, but again by the time you turn on a comp i have it done.

 

[Bill the gasman]

Kirkgas you are spot on with your short cuts I have been doing them that way for years. I had my GSR inspection in June and the guy said my calculations were wrong so I checked them on the old corgi slide rule and they were well within 10%. anyway he carried on trying to get a satisfactory answer out of his laptop in the end he said there must be a fault in his software. GSR are not as good as they think.

 

[gbgas001]

time for two mins or one revolution and go look the answer up in the tables in the corgi esentials book page 204 - 206 (5th edition). is the way to go

or if you use a smart phone there is a free excell program that will do it for you on the website

gb-gas

 

[Dotty]

or if you use a smart phone there is a free excell program that will do it for you on the website

gb-gas

Dead handy, cheers cocker!

 

[gbgas001]

Dead handy, cheers cocker!

No Probs, thats what its there for.

I will say its working with a CV of 38 mJ not 39mJ as the gas board uses... This is because most manufacturers use a CV of 38mJ on there data badges.

Cheers
gb-gas

 

[GreenArmy]

or if you use a smart phone there is a free excell program that will do it for you on the website

gb-gas

Ive had that excell sheet on my iphone for a while now, its a great idea but not very easy to use (i just look on the chart in my corgi book). Have you ever thought of developing this program into a proper iphone app?

 

[tamz]

Whats an iphone

 

[gbgas001]

Have you ever thought of developing this program into a proper iphone app?

I have thought about devolping them, but got to say it cant be much easier than the spread sheet... and i would need to split all the other calculators into different apps too. I dont prefer the I phone myself but there is no reason it couldnt be done..... watch this space (i will write it for windows phones first though) lol :

 

[derrybongo]

Hi Lads

I also use the iphone excell spreadsheet. The phone is usefull to for the stopwatch on the 2 minute count.

Derry

ps all this new fangled technology what next digital manometers !!!!!!

 

[CMairiD]

Love the iPhone. Hate the digital manometers.

They are ok for burner or fan pressure, but trying to peg 10/20mbar (or thereabouts) for a tightness test is pain.

Unless you lovely lads have any handy tips ...

 

[Blake]

Where is this spread sheet you speak of?? I've looked but can't find, it is early though granted can some kind folk post a link ? Cheers

 

[gbgas001]

Where is this spread sheet you speak of?? I've looked but can't find, it is early though granted can some kind folk post a link ? Cheers

its not fair for me to advertise but if you go to website thats on my picture, then go to free downloads ... the product is "gas calculator" or gb-gas.co.uk/page_20.html

 

[james the plumb]

thanks guys especelly kirk. i have spoken to the inspector before and he seams nice. just dont want to loose my registration. lol

 

[kyle]

Hello guys, I'm gunna ask a silly question but its one I am never told in class. I know how to gas rate using the book method and short cut method. My question is how do we interpret the figure we have worked out. I know if we have a 20kw boiler we should get aprox 20kw from our calculations ( give or take 5%? / 10%? ) . Which figure, 5% or 10% do we use. And secondly what would we do if the reading was say 3 or 4 or 5% out. And another question, when I have seen gas rating on a gas hob, engineers just record the figure ( I have seen between 6kw and 13kw and with between 3 burners lit,4 burners lit, and 4 burners and oven lit on freestanding cooker) on the paperwork and job done, how do we interpret readings on the gas hob if the elec oven isnt removed and we have no data badge or paperwork to work from?, is it acceptable to just record the reading and leave it at that, assuming flame picture ok.
Thankyou in advance for your replies; kyle.

 

[kirkgas]

you will hear different people quoting 5 or 10 %, cant say for sure if there is a RIGHT variation, technically to gas rate properly, you NEED, the MI (especially for a cooker/hob as some have different gas rates for different rings) you NEED the EXACT Calorific Value of the gas, (this is why i believe we have a variable of 5-10% as we never know the exact CV), you also NEED to be ACCURATE when you measure, so given the chance of not hving everything 100% then we have a variable, i use 10%, so if i gas rate and it is miles over, i do it again (as i have likely pressed the wrong button on the calculator,) a second rating usually clears it up, if im well under i again re check, and if still well under i check inlet pressure at appliance, then meter to see what gas i have, if gas supply is ok and gas rate is well down it simply means i need to investigate the burner or injectors, a clean out and retest should bring the reading up to where is should be,
hope this helps a bit