That's figure referred to is more associated with pipework testing requirements above which an engineer has to be commercial qualified due to the procedures used.
It's not a figure that relates to the capacity / sizing requirements of a meter or system design.
OK I understand - not appropriate
[automerge]1572538971[/automerge]
I guess he means it will be into commercial scope on your sized pipe work volumes
Many thanks for all comments.
I have been doing a little research - time permitting - and the most useful info I have come across is from posters to this site! It's a great pity that very useful info an considered opinion and facts from experienced and knowledgeable engineers is hidden away in old posts and forgotten - there must be a way to hive off the most useful into a separate section so they can be referenced easily and updated when superseded, eh Mod?
Anyway, the first point relates to 'diversity factors' (Kirkgas - Jul 6 2012) when calculating max. flow rates. I'll leave you to look up the post, and the few prior for context.
But essentially: "...A diversity factor is given to each type of appliance according to the normal degree of intermittent of use. Where there is only one or two appliances (e.g. combination boiler and cooker) the diversity factor shall have a value of one. Where there are more than two appliances the diversity factors listed in Table A.1 shall be used."
Relevant bits from Table A.1: "Combination boilers 0.8, Hotplates 0.6..." (Taking mfr's Gross input values).
So in my case it is: (28 x 0.8) + (35 x 0.8) + (8 x 0.6) = 55.2 kW x 0.094 (easier way to conv. kW/h to gas rate - see Kirkgas's following post) = 5.188 m3/hr.
Which a U6 of 6m3/hr should be able to cope with. (So this seems to be saying: don't simply add up all kW of all appliances there's more to it).
Next, static volume of gas in pipework, less than 0.035 = domestic, greater than this = commercial. (Cadent engineer). My installer is giving me grief over this, I will shortly go over his calcs. with him, (he's been called for some 'emergency' commercial work in a hospital).
Add together ivp (installation volume of pipe) + ivf (installation volume of fittings) + ivm (installation volume of meter) to get total static volume of gas in system.
In my case this is: ivp= 16.1m of 28mm + 7m of 22mm + ivf= add 10% of ivp + ivm of U6 or U16 meter. (Similar to Tamz - Dec 21 2013)
=> 16.1 x 0.00054 (vol. of gas in 1m of 28mm) + 7 x 0.00032 (for 1m of 22mm) + 0.0010934 (10%) + 0.008 (for U6) or 0.025 (for U16 - Cadent engineer))
=> 0.0200274 m3 for U6 or 0.0370274 m3 for U16. So a U6 is OK but a U16 makes it in the commercial range.
So a U6 meter should suffice from both points of view.
If anyone knows different, eg. the figures are wrong / this ... has been superseded with this .... / the regs. .... say this..... / diversity factors no longer used, use this instead / etc., etc. Please let me know. (I am a little nerdish in needing to know figures and reasons behind procedures and actions, especially when asked to cough up £££'s more).
Btw. the Cadent engineer visited. Took one look at the set-up (basic U6 in the usual white box fitted to the outside of the house), took a photo and said '...yeah, upgrading to a U16 or fitting an additional meter to your supply would be no problem'. I asked if he needed to do any measurements, he said no, he could tell by looking the supply would be OK, no calculations required. When I rang the office they said '...we'll need a week to do the calculations and send you our report, you can't get it any quicker...' Happy days!
Thanks for reading.