Hi,

I am currently in the process of putting a kitchen in my home. The old cooker was electric but I plan on getting a new gas cooker. I have the floor up at the moment and there is a 15mm copper gas pipe running straight across the room to the gas fire. That is the only gas pipe anywhere near this room. Can I assume that the gas fitter will be able to link directly into this pipe to take off a new feed for the cooker?

The reason I am asking is that if this is not possible then I don't like the idea of having to tear my house to pieces to run a complete new gas pipe from the meter to the cooker point. I live in a large Victorian townhouse and the gas meter is on a different floor and a long way away from the cooker point. If linking into the gas feed for the gas fire is not possible then I may have to stick with an electric cooker.

You'll be sticky to an electric cooker by the sound of it.

No information to even start to answer the question, but 15mm is not a lot.

What is on the gas at present, what size pipe back to the meter, and if a boiler what make/model.

If you're planning any future work, then whilst half the floor is up.

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Hi,

Oh dear, I don't like the sound of that. At present there is a 22mm pipe coming from the meter. That pipe goes to the boiler which is a large Worcester Bosch combi (not sure of the exact model but it's the 2nd largest combi that Worcester Bosch make at present). The 15mm pipe branches off the 22mm pipe and goes straight to the gas fire in the kitchen. There are no other gas appliances in the house. I was hoping the gas installer could link into the 15mm pipe under the kitchen floor and take a feed off it for the gas cooker.

What is the approximate total length, from the meter to the boiler, and the number of bends.

22mm would be undersized for most combi's on a long pipe run, not counting the fire.

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Hi,

The approximate total length of 22mm pipe from the meter to the boiler is around 10-11 metres and there are approx 6 bends (elbows) from memory. The 15mm pipe branches off from the 22mm pipe approx 5 metres from the gas meter. The 15mm pipe goes straight towards the gas fire which is around 4 metres away. Near the fire it is reduced down to 8mm microbore copper tubing to go into the fire. The cooker point will be approximately halfway in between where the 15mm pipe joins the 22mm pipe and where the 15mm pipe meets the fire (i.e. 2 metres from the 22mm pipe).

Thanks ever so much for your advice by the way, this is really appreciated. The above dimensions are all from memory but I can check to be certain when I get home.

Ok, lets round it up to 15m including the fittings.

Say the boilers is 30 Kw and the fire is 7Kw that gives you 3.45m³/h.

15m of 22mm will deliver 3.6m³/h, so right on the button with no room for additional appliances.

Please note for actual, you would need to supply all the information.

And it ain't Corgi anymore, it's Gassafe.

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OK, many thanks. I can now see how the pipe sizing affects the outcome. It's all down to the available flow of the gas. So, it looks as though it's going to be a right nuisance in my case. If I were to get the fire disconnected so that the 15mm pipe only supplies the cooker would that be OK? Ideally I would have liked to have kept the fire but I could have it permanently disconnected if necessary. I assume I would also need to know the Kw of the cooker for you to be sure.

Yes, I know Corgi is now Gassafe, I just keep forgetting, sorry.

If the 15mm serving the fire was disconnected and diverted to serve a cooker, you go up to approximately a 7Kw cooker.

But; that depends on the actual boiler model.

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OK, thanks Scruff. I will check the Kw of my boiler and my cooker. It would be much easier to have my fire disconnected than rip the house to bits putting in new pipework. I will get all the exact figures and post them on here when I get home. Many thanks indeed for taking the time out to help.

Not a problem, get the measurements etc, as accurate as possible.

I shall be out tonight, but one of the gas guys should be around, otherwise I'll look at it when I get in.

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Using rule of thumb, 15m becomes 30m with 2 appliances, 45m with 3.

I would probably upgrade to 28mm as far as the first tee to the fire, then 22mm to the tee where the cooker tees off.

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Dave

www.drlgas.co.uk

Hi gas4you,

Thanks for your input too. I'm finding this very interesting actually. It's amazing what info you can find out on here. It's interesting that the length of the pipe makes a difference and is something I don't understand. I can understand that the pipe diameter will affect flow but what difference does the length of the pipe and the number of bends make?

For example, if 15m of 22mm pipe gives 3.6m³/h of flow, what would the flow rate be if there was 30m of 22mm pipe?

Pipe sizing charts do vary, mine says that 15m of 22mm flows 3.4 cubic metres and 30m flows 2.3

To work out the length we take the measured length of the pipe then add 0.5m for every elbow or tee and 0.3 m for every pulled bend in the pipe, (ie pipebender) to get the total calculated length.

I'd go with Daves suggestion and upgrade to 28mm as far as the branch to the fire

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This is an interesting read & explains a bit.

http://www.ukcopperboard.co.uk/literatu ... sizing.pdf


Cheers.

Thanks Uncle Buck, that is incredibly useful information you have provided and I really appreciate it.