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Discuss Is my Gas installation at home domestic or commercial? in the Gas Engineers Forum area at

I had a problem with my Gas boiler and called an engineer out from a local Crondall, Surrey UK company.
The engineer felt my installation was commercial even though past engineers over 13 years have never said anything like this.
My installation is different as I have 2 x worcester bosch 30cdi (30kw each) and my understanding is that it needs to be over 70kw to be commercial.
He agreed (after talking to some people on the phone), then he noted I had 35mm copper pipe that ran from the gas meter outside my house to the boilers in my house. The distance was in his opinion between 10 and 12 meters long. I would agreed that is at most 10m but he said 12m.
I asked him to explain how he gets it to be "commercial" and he was unable to and said his manager said it was commercial and left!

So I did some research and I worked out the following:
1. My boilers are 2 x worcester bosch greenstar 30cdi each is 30kw so total is 60kw and therefore less than 70kw.
2. My pipework is copper 35mm to the boilers and then reduces. So lets say it is 12meters from the meter to the boiler.
3. The gas meter has the follwoing on it: a UGI meters Ltd, A Hanson PLC Company, 1993, 212 f3/hr pmax 50mbar, -071ft3/and R5 (I have attached a pic)

So my calcs are as follows (domestic is something where the gas in the pipework and meter is 0.035m3 total.
35mm copper holds 0.00084 per meter
The meter holds as follows:
E6 = 0.0024 = results in 39m length
G4/U6 = 0.008 = results in 32m length
G10/U16 = 0.025 = results in 12m length.
I am unable to figure out which type my meter is, but I guess it is one of the first 2.
I know I have ignored the x0.1 for fittings. But even then I am definately domestic.
Are my calcs correct?
any comments please?



I think you called a company who thought they could make some quick bucks by pressing a reset button or the like.

Obviously the person who attended didn't know anything and his manager knew less.

Look on the bright side:
They didn't do anything and didn't stuff anything up.
I've been to a job this week where a so-called expert had changed some parameters in the boiler and also left the thermostat with a foreign language on the screen.

He told the customer usual story: PCB need replacing as well as the thermostat.

Replaced flame sensor - problem fixed

Last Plumber

Gas Engineer
Advent Win
Your Meter is a U6.

It is more than likely undersized.

You would need to check the input for both boilers on full rate.

The Meter you have should only pass a maximum of 6 m3/hr.

If your pipework info is correct then it is domestic at present but once the meter upgraded to a U16, you will more than likely 'just' fall into the commercial category.

Hope this helps.

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