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

 

[kris]

ment to ask is there any other appliances in the same room?

 

[firemant]

Good point from Kris: re another appliance in same room?

Kirsty, re air changes. No, the fitting of cavity insulation will not affect ventilation. If they fit draught proofing, the fire should be spillage tested afterwards - but it will not affect the fact that the fire does not normally need ventilation, This is a specific issue for very new houses.
Frankly, I would get the fire checked anyway, after insulation:
http://www.manchestereveningnews.co.uk/news/cavity-insulation-firm-up-court-8637491

 

[Last Plumber]

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?

The spillage test carried out on the day, will pass or fail and generally give the indication that a chimney / flue is working.
It is carried out with windows and doors closed. The reason for this is so that the appliances flue is tested using what we call adventitious air.

As far as cavity wall insulation is concerned, in some circumstances, filling the cavity with insulation can, ( not always I stress), block ventilation that was designed to ventilate the underfloor area of a property, ( if you have suspended floors). This could ( in some properties), reduce the adventitious air entering that room and in turn effect the flue's operation ( unlikely but not impossible). This is why there is a necessity to have the fire tested after the wall is insulated. Some properties do have solid floors and in those type of properties, cavity wall insulation will have a lot less effect on the adventitious air.

Company's that insulate cavity walls have a responsibility for your safety but in most cases they are not gas safe registered Engineers ( I suspect), therefore they will have a very generalised view of this situation and will not want to get involved with your fire.

If they insulate your wall and your fire spills products of combustion, afterwards, they could be found liable, hence their stance.

Will they not insulate the wall on the understanding that you take responsibility for having the fire tested after they finish?

Show them the manufacturers installation instructions and offer to sign something that takes responsibility away from them.

It should be tested after the wall is insulated anyway in my opinion, it is not impossible for insulation that is pumped into a cavity wall to enter the flue itself. Again, these things are all very unlikely but happen on occasion.

If they do fill the cavity wall, make sure ( please) that you get the test done by a gas safe registered engineer, so you know the fire is safe.

 

[Gasmancoops]

The confusing bit from the manufacturer is that they have quoted BS 5871-3 in their installation instructions which is the British Standard for DFE's. All DFE's need ventilation typically but if the manufacturer is claiming a vent is not required, this takes precedence over the standard providing the appliance PASSES the spillage test.

The regulations dictate that if someone is doing something to house/property that may affect the safe operation of an appliance, then it is their responsibility to ensure the appliance continues to work safety after the work is completed. (REG 8(2) GSIUR states:

(2) No person shall do anything which would affect a gas fitting or any flue or means of ventilation used in connection with the fitting in such a manner that the subsequent use of the fitting might constitute a danger to any person, except that this paragraph does not apply to an alteration to premises.

Therefore the business carrying out the cavity wall insulation has a duty to ensure the fire works safely so they should either carry out the spillage test or arrange for someone to do it.

Hope this helps.

 

[jtsplumbing]

Lots of very good advise given , new styles vents will let in extra air and reduce the chance of draft, vent does not need to be visible so could be located behind something , Doing spillage test is very hit or miss depending on a lot of factors, Test at 9am it could fail do same test at 10am and it could pass, so for your own pice on mind fit a vent !

 

[Whyme]

the 7kw your talking about is to do with gaps in the house ie windows doors floorboards etc, not owt to do with the cavity of your external wall. go with instructions get insulation done then get engineer round to spilllage test. then if you need one you need one.

 

[firemant]

Whyme, you clearly have not read the OP

 

[kris]

A 7kw gap that's a new one to me lol, Whyme think u picked her up wrong mate,

 

[firemant]

The 7Kw allowance is because, until the advent of modern construction methods, it was considered impossible to draughtproof a house to the extent that you can prevent the ingress f enough fresh air to support the complete combustion of 7Kw of gas. Proper DFE's are different in that there is absolutely no control of air passing through the flue, increasing the volume of fresh air required. So Whyme is actually correct, if you analyse what he means.

My point about the OP is that the installers (of the insulation) are refusing to complete the work without a vent.

 

[kris]

I know mate it was a joke,, Jeepers wits happened to the banter

 

[firemant]

ok. missed the "lol".
But this thread is so full of nonsense

 

[Kirsty]

Thanks for all the advice, lots to think about, will get back to the cavity wall guys much better informed and see what they say but the fire is not going to be used whatever we do until I get a spillage test done. Thanks all

 

[Scott Robinson]

Hi Guys,

I am doing some online assignments in Sydney and came across this forum for spillage tests. The question that i have been asked is to briefly describe the steps to perform the spillage test.

Can someone help me out please?

Cheers Scott

 

[Johny1092]

Some DFE do not need the vent (when below 7kw) as per MI - when heaving oxygen depletion sensor fitted