DFE ventilation requirements

[Kirsty]

Quick question about ventilation for gas fires with cavity wall insulation

We would like to get cavity wall insulation, we chose a CIGA registered installer and have been told we need a vent in our lounge as we have a fire. I have looked at the "CIGA flues, chimneys and combustion air ventilators" guidance and my understanding of it is that under 7kw is fine and doesn’t need a vent unless its a DFE and then it isnt clear other than to consult the manual or seek technical advice.

The installer says that because its a DFE then it will need a vent. It’s a Magiglo Elite 16 fire, which is a 6.9kW DFE fire. I have had a look at their manual and it says it doesn’t need a vent unless it fails a spillage test but doesnt mention cavity wall insulation at all in relation to this- so does this change things?

From my manual:
"For models with heat inputs not exceeding 6.9kW additional ventilation is not normally required in the room that the fire is fitted. However, if spillage is detected during spillage test additional ventilation may be required. In GB reference should be made to BS 5871art 3, which makes clear the conditions that must be met to demonstrate that sufficient ventilation is available"

I've asked the installer about this and they say as its DFE it needs one. They have given me the details of someone to call tomorrow to speak about it further but I wanted to check if I was missing anything. I really don’t want an unnecessary vent, due to concerns about drafts, bugs and aesthetics but understand if I do need one for safety reasons. So if I dont need one and they insist I would consider asking an alternative installer but I feel bad since they spent ages assessing the property to apply for funding etc, and don’t want to waste a second installers time if I’m misunderstanding and they are correct about the requirement.

Any advice gratefully received.

 

[oz-plumber]

Hi Kirsty,

From what I read and understand, it seems like the installation instructions are a 'Get out of Gaol' card for the manufacturer.

They are putting all the onus on your health and safety onto the installer.

The manufacturer has a product that makes the requirement by 0.1 of a kW, but cannot be certain whether this 0.1 of a kW will be suitable to pass the requirements of your particular situation.

So, basically, you have 1 chance in 70 that you will not require additional ventilation.

As an installer of similar products, I would walk away from the installation due to the 'Get out of Gaol' clauses 'supplied' by the manufacturer.


The reasons:
Too close to the kW requirements ( 0.1 kW)
Subject to a smoke test - do you want the installer to install the product and then have to pay extra to have adequate ventilation provided.

The ramifications:
You could end up very ill or dead.
The installer will have the consequences on his mind for life.

 

[Last Plumber]

If it is a DFE it needs ventilation unless Manufacturers instructions say otherwise.

In your case, it sounds like they've left it up to the installer. If I installed it, I would want to install a vent. On the day it was installed and tested for spillage it probably passed, however, those circumstances, weather, temperature, wind etc can all change and I for one would be unhappy to leave a DFE without ventilation.

The reason for this ( apart from what OZ said about the 7kw which is also correct), is due to DFE fires being installed/situated beneath a fully open flue ( just like a coal fire).
The lack of restriction on that type of installation (because it is fully open), means that a lot more air can be drawn from the room than there would be with a different type of fire, so a lack of ventilation supplying the room could cause the fire to spill products of combustion in certain circumstances.

My advice would be to install a vent. From a legal point of view, if the Manufacturer says it does not need one and the fire has been tested by a gas safe registered engineer and he/she are satisfied that it is safe, you don't have to have one.

I Hope this helps.

 

[firemant]

Kirsty:


Your manual states it does not need ventilation. Ergo: It does not need ventilation, subject to a satisfactory spillage test.
The possible exception is with regard to houses built within the last 10 years or so. Modern houses are very well insulated, and almost draught proof, restricting the "air changes" in a room. But because they are so well insulated (and inherently "warm", few fires are fitted into them. I can't be bothered checking the actual figures, and I now have little to do with new homes and open flues, but if your home is 20 years old, then it is not relevant.
Generally, a "basket" type fire always needs at least 100cm2 of free air, those that are in their own "housing", often don't: your fire is in the latter category.

Don't worry about upsetting them. You need the right advice, and should not be bullied into having to have a vent, if one is not required. The problem is that they know nothing abut the gas industry, and they are simply covering their backs, in lieu of knowing the facts. The further problem is that they all seem to follow the same (wrong) hymn book.

Magiglo were bought by Burley fires in Oakham, some years ago. They may be worth talking to. :
http://burley.co.uk/contact-us/

 

[Chalked]

Hi
There is only one way of finding out if a dfe needs an air vent. That is to do a proper spillage test. If it passes it's ok, if it fails, it needs one.
Ask a gas safe engineer to do a spillage test.

 

[Kirsty]

Thank you for all your advice, its really helpful

Oz-plumber- when you say walk away from the installation what do you mean? The fire has already been installed (before we bought the house) without a vent. The only reason this has become an issue now is because the cavity wall guys want to retrofit a vent. Im set on the cavity wall but just trying to work out if a vent is needed or not. When you say we could end up dead, is this solely because of carbon monoxide? We already have a carbon monoxide detector near the fire, so if I had that and arranged a spillage test would that reduced the risk to an acceptable level?

Last plumber- you say spillage test can vary, I know nothing about the spillage test- does the spillage test give you a yes/no or a quantified result? Ie would a spillage test let us know how close it may be to failing the test if conditions vary like you suggest?

Firemant- Thank you, thats really helpful, I had thought about asking Magiglo but couldnt find any contact details. The house is 1960s/1970s but the cavity wall installation we want would I guess change the house to similar to the newer houses, which is where I guess the cavity wall guys are saying the need for a vent may occur? We have only been in the house one winter and it was cold- hence the plan for cavity wall insulation- if it does its job then we might be able to not even use the fire as the room has radiators too.

Chalked- I had thought about doing another spillage test, presumably the cavity wall installers are saying that the cavity wall installation might affect the results, so I assume we would have to do one after the cavity wall has been installed, and they wont install without a vent so I guess I might need to get a spillage test before and after? We are fairly competent DIYers so although I wouldnt touch gas I'd be quite happy fitting a vent after the cavity wall if a second spillage test showed it was needed after the installation had been completed but its whether the installers would accept this.

Thank you

 

[Chalked]

Who is doing the spillage test?

 

[Kirsty]

Well I assume the cavity wall installers dont have anyone on their team who knows enough to do it and that is why they just say vent to all so that they can guarantee its safe, so I would have to get a gas safe engineer to do, which is why I'm not sure if this would need to be before or after or both

 

[Simon F]

the insulation company tell you to get a vent to cover themselves.
the issue is a little cloudy with your fire as there is a potential for needing a vent anyway.
the insulation could change the air flow through the walls so a test would definately need doing after the insulation is fitted.
the insulation job might never get done if you don't have the vent fitted first.

 

[kris]

Standard is go by manufacturers guidelines or standard 100cm2 free area vent . That's for DFE fires up to 7kw