Gas fire flue

[hummingbird]

The gas engineer who came to service the inset gas fire said he was concerned about the flue. This is because when it is windy, the flames come out into the room and I have to turn the fire off. Obviously this wasn't right and I can see why he's had to cut off the gas supply.

He could only see 2/3 of the way up the flue and he said to inspect the rest of flue would mean removing tiles from the roof and looking down the flue from the top. He said this could be 2-3 hours work and no guarantee that the flue would be suitable even when he's inspected it. He said if the flue is the wrong size at the top, he still wouldn't be able to pass it. He's recommended a sealed unit with a balanced flue instead of an inset one.

I really don't want a sealed unit. According to past invoices, previous engineers have done a flue pull test which it must have passed (although I'm not sure what a flue pull test is). Could there be something else blocking the flue which was causing a down draft? Could it be a build up of soot? The house is about 17 years old.

Other opinions would be very much appreciated.

 

[Corgigrouch]

So what opinion would you like us to give? One that suits what you want to hear perhaps?

If you really want to have a gas fire, then a balanced flue fire is your obvious solution... though I find that most gas fires are disgusting bits of bent tin with the aesthetic appeal of a gangrenous wound

 

[muggles]

I don't see why he needs to remove tiles to look down the flue, it should be coming out of your chimney so he just needs to look down there. I'd start by getting it swept, if a sweep can't get his brush up there you know there's a problem, if he can then it's OK. Much like a car MoT though, a flue flow / pull test only says that it is OK or not at the particular time of day and in the particular weather conditions in which the engineer has visited, there's no guarantee it'll be fine the next day when the wind is in a different direction, ergo those who have looked at it before may well have got a satisfactory test but your latest engineer didn't.

You should have a good quality carbon monoxide detector fitted in the room the fire is in, something like a Honeywell H450EN is perfect. You can do this yourself.

 

[simond]

I think in this scenario I would get the chimney swept before I wrote off the existing installation.

It will be relatively inexpensive (typically £50-£90) and may find the problem.

I find the roof tile comment interesting, because good chimney design requires the stack to extend a considerable height beyond the roof, as adverse weather conditions can cause downdraughts otherwise.

If your chimney has been truncated or incorrectly installed, a balanced flue GF may well be the solution.

I'd agree with Corgicrouch's sentiments, open flued gas fires have no place in the modern world.

 

[muggles]

Blimey your sweep's expensive Simon, unless you're including the removal of the fire in that, our one charges £30

 

[FiremanT]

I am guessing that you have a pre cast flue, going on what your fitter said. There may be a restiction comprising (as weird as it sounds) of cobwebs. It is easy to sweep the first section (in the wall) but to get to the loft section requires dismantling. I would dismantle rather than lift the terminal off, simply because you need to get into the bend exiting the wall.

Do you have an extractor fan elsewhere in the house?

It is fair to oint out that these jobs have no guarantee of a succcesful outcome, but the time still has to be paid for.

If you had a a balanced or fan flue, would the terminal exit into your own garden with at least 600mm before the boundary?

And don't listen to that Croydon guy. He's ALWAYS Groucvy

 

[hummingbird]

Thank you very much for all your replies. I'll try to answer some of the queries:

A previous engineer increased the height of the flue stack. I think it was that engineer who also said I had to have a vent put in the wall (although the instructions for the fire says it doesn't need a vent) in order to stop the downdraft, but this engineer says the vent is too small and it would need a larger one.

It's a dormer bungalow with all the "loft" section being bedroom/bathroom space, so there's no internal access to the chimney. I think this is why the engineer would have to remove tiles from the roof to get at the stack from the outside.

There is an extractor fan in the kitchen.

With a balanced flue, the pipe would extend into my drive, which is one of the problems with having a balanced flue fire. It's a very narrow drive and the car can only just get down it as it is - with an extended pipe jutting out, I think there might be a problem with the car.


I think the chimney probably does need sweeping because the coals generated a lot of soot, but how likely is it in a modern house that the stack could still be too small if the engineer dismantles the roof to look? Are there some models of fire which are suitable for a narrower stack?

Thank you again for all your comments.

 

[FiremanT]

A previous engineer increased the height of the flue stack.

Is this a metal flue?

I think it was that engineer who also said I had to have a vent put in the wall (although the instructions for the fire says it doesn't need a vent) in order to stop the downdraft, but this engineer says the vent is too small and it would need a larger one.

Fires below 7Kw input don't need a vent - subject to a satisfactory spillage test. Normally, if it spills on test, one would open a window to emulate a vent. If it still doesn't "pull", then a vent won't sort the problem. FYI, I have never needed to fit a vent in these circumstances.

It's a dormer bungalow with all the "loft" section being bedroom/bathroom space, so there's no internal access to the chimney. I think this is why the engineer would have to remove tiles from the roof to get at the stack from the outside.

If it is a metal or asbestos flue, then you might have a problem!

There is an extractor fan in the kitchen.
Was the fire tested with this ON?

With a balanced flue, the pipe would extend into my drive, which is one of the problems with having a balanced flue fire. It's a very narrow drive and the car can only just get down it as it is - with an extended pipe jutting out, I think there might be a problem with the car.

Fair comment.

I think the chimney probably does need sweeping because the coals generated a lot of soot,

Not neccesarily relevant

but how likely is it in a modern house that the stack could still be too small if the engineer dismantles the roof to look? Are there some models of fire which are suitable for a narrower stack?

It depends on whether you have a proper chimney, or as I thnk more likley, a precast flue. A proper chimney could be lined, a PC flue is going to be as small as is allowed.

A picture of the terminal would help.

 

[hummingbird]

Thanks for your response, and I can take a photograph of the terminal tomorrow.

Re the question about testing the fire with the extractor fan on - the fire wasn't actually tested. When the engineer saw that the front section of the coals was broken (I mentioned this on a thread about coals a week or two ago), he said he couldn't service it anyway. The fire had been getting difficult to spark because of soot, and by the time of the engineer's visit, it had stopped sparking altogether. We'd got talking about the flue because I told him about flames coming out into the room when it was windy, and he could see discoloration around the fireplace and the ceiling. So I asked him to check the flue whilst he was here, thinking that I would get a new fire anyway, and then it all came to light that it might not be as simple as that.

 

[FiremanT]

OK, Thats raised a couple of more thoughts, but I'll comment when I see the pics. Where are you located?

 

[biscuit77]

Coals broken,flames coming into room,soot.... No brainer for me this fire would be chopped and nomway i'd be attempting to fix it. If you do want a gas fire as previously advised get a fan flued fire.

 

[hummingbird]

I'm not trying to fix the existing fire, biscuit77 - it's already been dismantled. And as I mentioned, I don't think the car would be able to get up the drive if I had a fan flue fire because of the pipe extending into the narrow drive. What I'm trying to do is understand more about the flue and whether it is (or could be made) suitable for a new inset fire before paying several hundred pounds on what could turn out to be a wild goose chase.

 

[Corgigrouch]

Block the flue off permanently and fit an electric fire with a holographic flame picture... That way you still have the cosy flickering flame effect without having to resort to wasting gas and heating the great outdoors.

Or.... Have a nice log burner fitted

 

[hummingbird]

Here's a picture of the flue.

//www.diynot.com/network/hummingbird/albums/


Corgigrouch, thanks for mentioning hologram fires - I might end up having to have an electric fire, but I'd rather not if it can be avoided.

 

[FiremanT]

Okjay. the pic shows that it is a Selkirk IL flue, which is a twinwall. The fact that it has been extended indicates that this isn't a new problem. With that height, assuming it is a house and not a bungalow, it should be pulling like a train!

However, you have aproblem in that the flue is fully boxed in. Your best case scenario would be a sweep with very flexible rods sweeping in both directions, trying to get past the junction of the wall section and the meatal section. This should be followed by a basic smoke test and then a more rigorous one, where the bottom opening is blocked off, a smoke pellet dropped down the flue, and the top blocked. This is to ensure that no joints are leaking in the boxed section, either currently or as a result of the sweep.

I asked the question about the fan as it is working in the opposite direction to the flue. If the fan is too powerfull, it will suck the products back down. I've only had this once in a house, where the owner was very proud of the "kitchen fan" that he had nicked from work, and a couple of times in pubs. Is there any chance that the fan was on when you observed the flames coming out of the fire?

As an added note, most inset fires don't have a down draught diverter, so flame disturbance is not entirely unusual in some conditions. Also if ypou have tall buildings or hills around you, you may suffer this.

The bottom line is that you take a risk of spending cash for an unsucessful outcome, or changing to power, balanced, flueless (ahem. I fit them and my only concern is the vent situation, but the OP has one anyway), or electric. Look at Valor Dimension or Dimplex Optiflame. If you buy from a proper shop, you MAY get a longer warranty, subject to their status (We offer 3 yrs on Valor and 2 on Dimplex, bot FOC from Manufacturer).