Gas Cooker Question

[flashharry]

Hi All,

I've moved into a house that has a nice new looking Worcester Bosch 30cdi combi boiler powering the hot water and central heating, which works a treat. However, the kitchen has an ancient electric cooker (I don't think the previous occupants were that clean on cooking) which I'd like to replace with a gas one.

The gas meter is in the cellar and boiler upstairs (there are no other gas appliances in the house) with a run of about 9 meters of 22mm copper pipe supplying the gas to it (all looks neat and tidy). In my naivety I assumed that you'd just be able to take a spur (that's the electrical term - don't know what it is in plumberspeak) off of this and power the new cooker.

So far I've had two people come and quote, one said we could do the above, the other insisted that all the pipe work to the boiler would have to be replaced with a larger diameter pipe - thus making his quote about twice the size of the first.

I'd be interested to hear peoples opinions on this.

Thanks

Harry

 

[macfudd]

2nd guy is taking the p**s imo.
Go with the 1st guy.

 

[landyandy]

Hi.

Gas pipework does need to be correctly sized to each appliance.
It is possible that when the boiler was installed, the pipework sized was just acceptable in 22mm. So now adding another appliance might make the 22mm undersized. I am just saying it is possible.

Calculations have to be made taking into account the heat input of each appliance, the length and number of bends etc. in the pipework and the pressure loss to each appliance.

A Corgi registered engineer will be able to advise you on this.

Andy.

 

[John506]

If you want to check yourself for your own peace of mind, I have uploaded the formula with the tables to work it out.

http://www.mediafire.com/file/dfmmyn5jley/Pipe_sizing.doc

 

[DP]

Macfudd, can you expand on your reply?

My thought is that the gas line is sized for the boiler that is fitted to it. 9m may not be the calculated size (including bends etc) but point to point measurement. There of course are instances where the installer could have calculated for a gas cooker installation at a later stage, but the line would need to be checked to ensure it will allow extra loading. Better option would be to run a pipe from cooker location to gas meter or a point on the existing gas line that will allow acceptable pressure drop.

 

[flashharry]

Thanks for the replies.

John506, I will try and work my way through that document over the weekend

So, if I understand correctly, if the existing pipework to the boiler is just inside the 1mbar pressure drop limit then the simplest option would be to run a separate gas pipe from the cooker to meter and it would not be necassary to replace all the existing pipe work? (In fact, the way the house is laid out, running a pipe to the meter, rather then the existing pipe would only be another 3m or so)