Gas fires keeps going out

[Roger Mills (aka Set Square)]

How are the pipes routed? Do the fire and boiler share the same pipe, or do they have independent feeds all the way from the meter?

[Chris Cowley]

The (CORGI) bloke who installed my combi last year used 15mm on the branch to the combi (with a 22m reducer at the back of the boiler) because that's what was already there to service the old boiler. Whenever the boiler initially fires-up (e.g. when a hot tap is turned on) the cooker flame visibly drops for a split second - not quite enough for it to go out, fortunately. It does sound like the OP has a similar, but slightly more extreme, version of the same problem to me.

[Roger Mills (aka Set Square)]

Unless the 15mm pipe is shared by the boiler and fire and/or cooker, the thin pipe itself is not the problem. The problem is that when there is a sudden demand for a high flow of gas, the governor on the meter can't respond fast enough - so there's a reduction in pressure until it's caught up with itself. There's probably a corresponding surge when the boiler shuts down.

[Chris Cowley]

So the problem (in my case) is the governor then? I'm not over-bothered about it at the moment, but my concern is if it gets any worse the oven may start to go out when the boiler comes on. I know the oven has some sort of safety mechanism which reduces the gas flow to a minimum when cold, but at the very least it means my dinner wouldn't be ready when I expect it to be and that's not good!

If there is a possible problem with the governor then maybe I should get Transco out? I assume it's their responsibility.

[Roger Mills (aka Set Square)]

It's certainly my belief - albeit from a theoretical point of view - that fluctuations in pressure are caused by a sudden demand for gas. I'm not sure whether the governor is necessarily faulty - or whether it's simply behaving like governors do! It is, after all, a fairly crude mechanical servo device which attempts to keep the output pressure constant by controlling the size of a variable orifice. If there's a sudden increase of flow rate it through it, it needs to open its orifice more. It's probably too much to expect that it will do this instantly with no pressure fluctuations - especially when you consider that gas is compressible. Appliances should hopefully be designed in such as way that they are able to cope with this.

[Chris Cowley]

Okay, thanks. I'll see how it is in a few weeks after the new oven and hob have been plumbed-in as the existing oven is a manky old thing that may not be in the best condition internally.

I'm surprised that modern high-rate combi-boilers and such like don't have a gas value that opens/closes more slowly to give the governor a chance of keeping up with the demand. I suppose there must be a reason ("cost" most probably comes into it somewhere - it usually does!). From looking at the recent posts here, this seems to be quite a common issue (I hesitate to use the word "problem", as it isn't necessarily a problem).

[sas65]

at the gas fire. I have the same problem. I run the hot water and the fire goes out. This does not happen all the time. Although when it decides to start play silly buggers it does it consistently. This is a 37 ft static caravan.

[Andrew]

2006 Post !!.

never mind, the next big storm will blow it away.