I am writing this guide because when I purchased a new Baumatic Range Cooker on eBay it did not come with a fitted bayonet hose. When I enquired about how to get it fitted and collected quotes, I discovered that CORGI registered plumbers had differing views about how the installation should be done. In fact they only agreed that even such a surely straight forward fitment would cost at least £100 simply because they had to be CORGI registered to carry the task out.
It is one thing introducing legislation that makes installations safer but quite another when it simply done to create an artificial economy resulting in increased costs to the consumer.
I found out that this work is not necessarily done safer or better by CORGI registered members. I found that CORGI registered members were out of touch with the materials that they should be using as well as the method. When I read the CORGI regulations I understood why. They are too vague and clouded. The technical ability of typical CORGI registered members is too low to enable a proper and clear understanding of the CORGI regulations.
So here we have the definitive guide.
FIXED HOBS and FREE STANDING COOKERS:
Always follow the manufacturer s installation instructions exactly. You may or not be able to use a flexible hose. The manufacturer s routing instructions are key because hoses are temperature sensitive.
Many cooker bayonet flexible hoses sold do not meet the latest BS standard.
Wickes charge £14 for such a hose that should not be used. Better made examples from the supplier below cost just £8. The flexible hose for a natural gas supply should be manufactured to BS 669 -1 Flexible hoses, end fittings and sockets for gas burning appliances. At the time of writing, 2007, accept nothing less. These hoses are a rubber sheath around a flexible steel hose. Earlier versions were all rubber.
CORGI members disagree over whether cooker hobs should be fed by fixed pipe or flexible hose. This is because they often do not understand the reasoning behind which route to take simply choosing one option and sticking with it. This is dangerous. Only the manufacturer can be responsible for knowing which parts of their products reach what temperatures during use. Thus you must follow their instructions. It is the CORGI regulation to follow the manufacturer s instructions.
Quoted from CORGI regulations: Fixed cooker hobs may be installed using a flexible hose, providing this is approved by the appliance manufacturer. The hob should be installed in accordance with appliance manufacturer s installation instructions and BS 6172 - Specification for Installation of domestic gas cooking appliances (2nd and 3rd family gases). The flexible hose for a natural gas supply should be manufactured to BS 669 -1 Flexible hoses, end fittings and sockets for gas burning appliances. Specification for strip-wound metallic flexible hoses, covers, end fittings and sockets for domestic appliances burning 1st and 2nd family gases. Similarly, LPG flexible hoses should also be manufactured to BS 669-1(LPG versions may be identified with either a red band or a stripe). The hose itself should not be subjected to temperatures in excess of 70ºC and should be located such that it will not suffer mechanical damage such as abrasion caused by surrounding kitchen furniture, which may be moved during use, such as a cupboard drawer or door. Guidance on the installation requirements of domestic gas cooking appliances is given in Gas Cookers and Ranges - Domestic (GID2) from the CORGI Gas Installer Manual Series.
The cooker or hob has a half inch male brass gas inlet connection.
A bayonet cooker hose also has a half inch brass outlet where it connects to the appliance. To connect this to your appliance you must use a chrome bayonet hose lock ring. These cost less than 30p each. Do not use anything else unless you know what you are doing!
The chromed lock ring sits between these 2 male connections (one end of a bayonet host & one end of an appliance). These two male connections sit inside a brass 'female-female half inch iron' connection.
If using a fixed pipe, then a female half inch iron connection is used.
You also need GAS rated yellow PTFE tape. Do not use other PTFE tapes which are not reinforced. Apply the PTFE tape to both male threads, overlapping each turn until the thread profile s knife edge can only just be observed, i.e. one more PTFE tape would suppress the knife edge character of the thread profile. No tape must cover the internal pipe - the wet area.
Tighten a half inch brass socket around the bayonet hose, after PTFE tape has been applied, so that half the socket plus the thickness of the chrome lock ring remains. Coil the hose into its bag so that you can then screw the other side of the socket onto the appliance inlet, after PTFE tape has been applied. Use pliers to gently hold the brass socket.
Liberally spray gas leak detector spray over all the joints to test for leaks. Instructions are one the tin but essentially you are looking for a stream of bubbles. The spray itself uses some bubbles. Test it several times with the gas supply on.
Hook up the stability chain as described by the manufacturer s instructions.
You just saved over £100 and have the peace of mind that you did the job right.
All the products mentioned can be obtained from toolstation or more expensively from your local plumber s merchants.
