Was correct diameter gas pipe used for my new cooker?


Postby Roy22 » Fri Jun 15, 2007 8:49 pm

What diameter of rubber connection hose is correct for my new freestanding gas cooker? The total power is 12.9kW, the oven alone is 2.5kW

The Corgi engineer reused an old hose he had (yes I know, he shouldn't have). My old cooker had a standard hose of about 20mm outside diameter, the same sort found in all the DIY stores etc. The Corgi man changed the wall fitting to accept a smaller hose (a right-angled bayonet fitting) of about 16mm OD, (perhaps used for built in cookers?) which had the correct male thread at the cooker end.

This is why I'm asking: The cooker works fine but the oven is underheating by about 20-30C (ie 2 gas marks) across the whole range. At top setting (9 or 10) it doesn't quite reach gas mark 7. This is confirmed via baking problems as well as by thermometer. I'm going to have to call out the manufacturer, free under guarantee, but there's a rider to the effect that if the fault is not with the cooker, they will charge me.

Are they likely to say that the 16mm rubber hose is abnormally small, and could be restricting flow, giving the reduced temperature? Or is the 16mm hose acceptable? I know that the copper supply pipe to the kitchen is similar (15mm OD water type pipe), but I don't know what internal diameter the 16mm hose offers and whether it's enough?
Roy22
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Postby htg engineer » Wed Jun 20, 2007 6:45 pm

There's cooker hoses with a bayonet type fitting on the end and a cooker hose with a micro point fitting, sounds like he has fitted the micro point hose to your installation.

The easiest way to check if the hose and the gas pipe are the correct size is to get a CORGI registered installer to check the gas pressures. Call the fitter that installed the cooker he will be able to check whether the fault is with the supply or with the cooker itself.
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Postby clulee » Sun Jul 29, 2007 8:18 am

[quote="htg engineer"]There's cooker hoses with a bayonet type fitting on the end and a cooker hose with a micro point fitting, sounds like he has fitted the micro point hose to your installation.

The easiest way to check if the hose and the gas pipe are the correct size is to get a CORGI registered installer to check the gas pressures. Call the fitter that installed the cooker he will be able to check whether the fault is with the supply or with the cooker itself.[/quote]

Can I suggest another alternative which might save you a bill? Get a stopwatch , and check the gas meter reading over two minutes with the cooker firing and hob rings all firing at maximum heat. Make sure that all other gas appliances served by this meter are shut off first. If the total heat input for the appliance is 12.9kW as you state, the meter reading should increase by 85 cubic feet ( or 2.4 cubic meters) in two minutes.
clulee


Postby clulee » Sun Jul 29, 2007 8:26 am

Can I suggest another alternative that might save you a bill? With all other gas appliances that are served by this meter shut off, switch the cooker and hobs to maximum heat, and if the appliance is rated at 12.9 kW as you state, the meter should increse by 85 cubic feet (2.40 cubic meters) in TWO minutes. It is a 2 minute test.
There is a bit of a sting in the tail though, a full test would be to do the same check with all the gas appliances firing at maximum at the same time, to ensure that the gas supply and meter were passing enough gas, but that is a bit extreme!
clulee


Postby clulee » Sun Jul 29, 2007 11:40 am

Before anyone howls at me, the calculation I gave in replying to this message a couple of hours ago was wrong. Very wrong!
The figures I gave would be correct if you ran the cooker for an hour, so to get the correct gas consumption for 2 minutes, divide them by 30.
The figures should have been 1.41 cubic feet in 2 minutes, or 0.04 cubic metres.
Sorry for the confusion!
clulee


Postby Roy22 » Mon Jul 30, 2007 6:23 pm

Thanks for the very interesting replies. I would certainly try this test if I still could do, but since posting this question some time ago, the cooker has gone back to the manufacturer due to the low temperature oven fault which a repair visit failed to fix.

So I am currently without a cooker, but still in the dark about the bayonet fitting that was recently fitted. I can now say that it is a 'micropoint' bayonet fitting, which sticks out horizontally, rather than the slightly larger diameter fitting/hose which normally point downwards.

Now I know that it's a micropoint, is this correct for a freestanding cooker? When I finally get a replacement freestanding delivered, will a new Corgi man find fault with this? I'm not intending to use the original guy again.
Roy22
Posts: 6
Joined: Thu Apr 19, 2007 9:56 pm


Postby htg engineer » Tue Jul 31, 2007 3:47 pm

It depends on the type of oven you get, if its a range type (normally 5 or 6 ring burners) then a larger diameter hose may be required, therfore requiring a bayonet fitting, but for a standard gas oven the micropoint will be adequate.
htg engineer
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Joined: Tue May 22, 2007 5:22 pm


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