Gas Rates and Heat Inputs

[bashmaystor]

Hi all

I have my probationary inspection next week, and I'm going through some of the things I might get asked about.
One of the things is this. How do I know the current Calorific Value of the gas, in order to use it as a figure in the formula?

I worked out the gas rate using this formula.
Example: 07341.954 - 07341.954 = 0.028m3 (in 2 minutes) X 30 = 0.84m3/h.

Now to work out the Gross heat input I use this Calorific Value: 38.5
0.84 x 38.5/3.6 = 8.98kw/h

Now to work out the Net heat input
8.98 / 1.1 = 8.1kw/h

My question is this: How do we know what is the exact Calorific Value of the gas on any given time?

Also what formula is best to use, as they give slightly different results?
Gas Rate x CV/3.6 = kw/h (8.98 gross)
or
Gas Rate x 30 x 10.72 = kw/h (9.0048 gross)

Sorry for the long post

Will be happy to hear your opinions


Kind regards
Veniamin

 

[billybob150811]

you should be able to get it from the gas supplier who supplys a particular dwelling in practice easier said than done it should be on their gas bill but gas is charged per unit volume not its CV
as for formula which ever your more comfortable with the figures in the MI have to be a best guess made by the manu as different areas can have different CV.s you could get the flow rate x delta t x specific heat capacity and get a figure in joules(same figure as watts)but I would keep the proby simple

 

[stevetheplumber]

use an app

 

[Riley]

My inspector encouraged anything that makes your life easier

 

[kris]

Hi mate use 38.5 mj3

 

[kris]

Yeh apps the best as long as you have your equations at hand .

 

[Dotty]

We discussing gas and gas training in open forum now?

Nope.

Veniamin, if you're getting your probie inspection then you must have your gsr number.

If so, pm gas man or REDSAW with your gsr details and get your yellow badge up.

If not we need another 77 posts from you then you can apply for the Arms.

Sorry old chum.

 

[Dotty]

Moved and reopened.