Gas rate app

[kay-jay]

No mention of checking the cv of the gas in any text book or reg I have seen. The difference is probably that minimal it has no affect.

Up to 5%

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[zeebeedee]

Probably not far of that in human error on the timing or readings

 

[zeebeedee]

Up to 5%

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So on a 24 kw boiler you could be 1.2kw out.

 

[Nostrum]

Sutely the badged input rating of the boiler would have to make an assumption on the CV of the fuel as well though, so in effect it doesn't matter. Only gas rating to determine the correct quantity of fuel is being used by the appliance, not to actually calculated heat production.

 

[EPH]

Well if BG say so then I'm ditching mine :willy_nilly:

Be better teaching some of the lads the back boilers need ventilation!

 

[Doodlebug]

Well if BG say so then I'm ditching mine :willy_nilly:

Be better teaching some of the lads the back boilers need ventilation!

Are you suggesting British Gas engineers work unsafely?


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[EPH]

Are you suggesting British Gas engineers work unsafely?


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I'm saying I regularly go to CF installs with no ventilation that used to be under a BG contract since installation but they can't afford it, when I tell them what needs doing I normally get asked to leave because "British Gas never mentioned that".

I can only speak from e pertinence and I wish I had a pound for every time it's happened.

 

[villa_tom]

I'm saying I regularly go to CF installs with no ventilation that used to be under a BG contract since installation but they can't afford it, when I tell them what needs doing I normally get asked to leave because "British Gas never mentioned that".

I can only speak from e pertinence and I wish I had a pound for every time it's happened.

Ive never been to a job anywhere for anyone where an open flued boiler has had no vents, blocked up vents yes, but no vent at all, no.
I for one know that safety is drummed into engineers at BG and there lads wouldn't miss this and if they did then it would be a massive defect and heads would roll.

 

[tamz]

The calorific value can make quite a difference to the calculations.
The cv of gas supplied through the grid varies from between 37.5 - 43MJ/m³ and the quoted values vary constantly.
No matter how you choose to work it out there has to be a margin for tolerance as you will never have the exact figures.

The calculation is MW ÷ cv = m³/s or simplified to the units we use (kW and m³/hr) we use kW x 3.6 ÷ cv = m³/hr
To do it from m³/hr - kW the formula is m³/hr x cv ÷ 3.6 = kW

As an example, say on a boiler burning 3scm/hr
If the calorific value of the gas was 37.5 the HI would be

3 x 37.5 ÷ 3.6 = 31.25kW

same boiler burning 3scm/hr at 40.5 MJ/m³

3 x 40.5 ÷ 3.6 = 33.75kW

same again at a cv of 43MJ/m³

3 x 43 ÷ 3.6 = 35.83kW

A bit of a difference.

BG wanting to ban the use of apps is not because they are wrong. They are not. They will just want to standardise their info they receive back by having there guys use the same method.

 

[GrahamM]

BG wanting to ban the use of apps is not because they are wrong. They are not. They will just want to standardise their info they receive back by having there guys use the same method.

Exactly! As I touched on previously. :wink_smile: