Ventilation for dfe fires.

[Blackcatgas]

Further to my other post about floor vents..... I went to a job today, the dfe fires been capped, the paper work says 100cm2 vent required, its a 10.2 kw fire, Ive calculated that it needs a 15cm2 vent, the installation instructions concur with this. Is there some new reg that I dont know about that says all dfe fires must now have a 100cm2 vent as a matter of course now?.

 

[Puddle]

No,100 cm2 is the smallest vent that can be fitted

imho

 

[Blackcatgas]

No,100 cm2 is the smallest vent that can be fitted

imho

I dont understand Puddle?

 

[southcoastboile]

mis overide everything but i thought the smallest vent is 100cm2 for any fire

 

[Billy Bob Bob]

I dont understand Puddle?

WHAT PUDDLES SAYING IS ALL DFE,S REQUIRE A 100CM2 VENT BCG(sorry for the caps my keybords stuck)

 

[Blackcatgas]

mis overide everything but i thought the smallest vent is 100cm2 for any fire over 7kw

Ahh, ok, this is the crack, the fire was fitted 8yrs ago,the manuufactures instructions say a 14cm2 vent is required, there is a 50cm2 vent into the floor void, Ive been outside and there is only the old victorian brick vents from outside into the floor void. what I was going to do was core a new black hole ventilator from outside into the floor void, this is 35cm2 because of the internal baffels.
Is this ok to do?. Cheers for your replies.

 

[Puddle]

Just because a DFE is under 7 kw does not mean it does not need added ventilation,all DFE's need ventilation unless otherwise stated by manufacturer and that ventilation shall be no smaller than 100cm2

 

[Puddle]

If mi says 140 cm2,fit a vent to suit through floor,you can increase ventilation under floor to outside if you wish but you should find underfloor vents already at front and rear of building,which should be adequate if meeting building regs

imho

 

[Blackcatgas]

Just because a DFE is under 7 kw does not mean it does not need added ventilation,all DFE's need ventilation unless otherwise stated by manufacturer and that ventilation shall be no smaller than 100cm2

Cheers Puddle, the dfe is 10.2 kw, the MI state a 14.6 cm2 vent is required, my calculations agree with this, I know the MI always overide anything, but...... will my above plan of work suffice or do I have to now put in a 100cm2 vent even though the old MI says I dont have to put one in that big?

 

[Blackcatgas]

If mi says 140cm2,fit a vent to suit through floor,you can increase ventilation under floor to outside if you wish but you should find underfloor vents already at front and rear of building,which should be adequate if meeting building regs

imho

14 (Fourteen) cm2 vent required in the MI.

 

[AlexGas]

Here we go, from the current BS:

BS5871-3:2005
Specification for Installation and maintenance of gas fires, convector heaters, fire/back boilers and decorative fuel effect gas appliances —
Part 3: Decorative fuel effect gas appliances of heat input not exceeding 20 kW (2nd and 3rd family gases)

8 Ventilation

8.2 Sizing
Unless the manufacturer’s instructions specifically state that purpose provided ventilation is not required, such ventilation shall be provided in the room or internal space containing the appliance. Where purpose provided ventilation is required, the air vent free area shall be a minimum of 100 cm2, or, where greater, as stated in the manufacturer’s instructions.

COMMENTARY AND RECOMMENDATIONS ON 8.2
Normally, appliances covered by this standard will require a minimum of 100 cm2 of purpose provided ventilation. However, in the case of an appliance of not greater than 7 kW input which generates a clearance flue flow not greater than 70 m3/h when tested in accordance with Annex A, an air vent may not be necessary.
The manufacturer’s instructions will provide details in such circumstances. It should be noted that Annex A describes a laboratory test which is not for use by gas installers seeking conformity with this standard.

Hope it helps.

 

[Puddle]

14 (Fourteen) cm2 vent required in the MI.

got that and edited to suit before this post,finding it hard to keep up this evening :dozey:

defo no need to increase underfloor ventilation to outside would of thought ,should be alot more than 14 cm2

 

[Blackcatgas]

8.2 Sizing
Unless the manufacturer’s instructions specifically state that purpose provided ventilation is not required, such ventilation shall be provided in the room or internal space containing the appliance. Where purpose provided ventilation is required, the air vent free area shall be a minimum of 100 cm2, or, where greater, as stated in the manufacturer’s instructions.


Cheers Alex, Iam sorry to be thick its been a long day, the manufacturers instructions say that extra ventilation is required, it states 14.6cm2. I was always taught that the manufactures instructions trump any regulation, so will the existing 50cm2 vent suffice or do I need to put in a 100cm2 vent becuse the MIs are old and not to current standards.

 

[Blackcatgas]

got that and edited to suit before this post,finding it hard to keep up this evening :dozey:

defo no need to increase underfloor ventilation to outside would of thought ,should be alot more than 14 cm2

Thanks everyone!

 

[AlexGas]

You got it! Stick to the MI.

 

[Blackcatgas]

I was still writing some of my replys when people had already replied, looks like I was being ignorant/thick. sorry.

 

[Puddle]

If it is an old fire and fitted before reg change,I would increase ventilation to 100cm2, as ventilation requirements must meet todays standards and sounds like mi's in this case are based on old standards

imho

 

[aggis]

If the DGF's MI states it doesn't need ventilation, thats the case as long as the client has the instructions.
Where as if it states it needs ventilation, the minimum is 100cm2 unless MI states it needs more.
100cm2 free air thro' floor & 100cm2 min thro' the vents into the under drawing in your case.

 

[kirkgas]

Further to my other post about floor vents..... I went to a job today, the dfe fires been capped, the paper work says 100cm2 vent required, its a 10.2 kw fire, Ive calculated that it needs a 15cm2 vent, the installation instructions concur with this. Is there some new reg that I dont know about that says all dfe fires must now have a 100cm2 vent as a matter of course now?.

apologies in advance if im wrong, but are you sure you read the MI properly? any dfe i've seen by definition of design needs a minimum of 100cm2
and at 10.2 requiring a vent it would be 10.2-7x5 is more than 15cm2 haha

 

[AlexGas]

Most of DFE's are under 7Kw and MI would say - purpose built ventilation is not normally required for this appliance.

We could have more appliances in the same room but this is another question.

 

[kirkgas]

Most of DFE's are under 7Kw and MI would say - purpose built ventilation is not normally required for this appliance.

We could have more appliances in the same room but this is another question.

if we do a vote of whether we have seen more that require a 100cm2 than dont, i think most people will say they have seen a lot of fires that do require it

 

[Puddle]

On the subject of dfe fires,would just add that it is important to gas rate them,manufacturers stating no extra ventilation required as say only 6.9 k/w,they base this on the 7k/w rule and but you will find many of these fires are over the 6.9 k/w stated on the badge pushing it over the seemingly magical old 7 k/w figure

 

[Blackcatgas]

[QUOTE=aggis;262808]If the DGF's MI states it doesn't need ventilation, thats the case as long as the client has the instructions.
Where as if it states it needs ventilation, the minimum is 100cm2 unless MI states it needs more.
100cm2 free air thro' floor & 100cm2 min thro' the vents into the under drawing in your case.[/QUOTE]



The MI states that it needs extra ventilation, 14.6cm2 to be precise, the vents/fire were installed 8 years ago. Do I need to upgrade to 100cm2 or will the existing vents (50cm2) suffice?.

 

[Billy Bob Bob]

[QUOTE=aggis;262808]If the DGF's MI states it doesn't need ventilation, thats the case as long as the client has the instructions.
Where as if it states it needs ventilation, the minimum is 100cm2 unless MI states it needs more.
100cm2 free air thro' floor & 100cm2 min thro' the vents into the under drawing in your case.

The MI states that it needs extra ventilation, 14.6cm2 to be precise, the vents/fire were installed 8 years ago. Do I need to upgrade to 100cm2 or will the existing vents (50cm2) suffice?.[/QUOTE]

upgrade to 100cm2

 

[Blackcatgas]

apologies in advance if im wrong, but are you sure you read the MI properly? any dfe i've seen by definition of design needs a minimum of 100cm2
and at 10.2 requiring a vent it would be 10.2-7x5 is more than 15cm2 haha

Hi Kirk ,defo 14.somthing, il scan them in tomorrow

 

[kirkgas]

Hi Kirk ,defo 14.somthing, il scan them in tomorrow

cheers, wasnt sure, only ever seen nil or 100cm2

 

[Simon F]

taken from "Corgi Fires and Space heaters" third ed page 56,

"unless the manufacturer's installation instructions specifically state that purpose provided ventilation is not required, a minimum 100cm2 free area of ventilation needs to be provided. the purpose of the ventilation is not only to provide combustion air for the appliance but also to satisfy the requirements of the unrestricted chimney".

 

[GrahamM]

apologies in advance if im wrong, but are you sure you read the MI properly? any dfe i've seen by definition of design needs a minimum of 100cm2
and at 10.2 requiring a vent it would be 10.2-7x5 is more than 15cm2 haha

I have viewed similar MI's that state the same small vent size for a DFE fire. The customer produced the old MI's for some ancient fire that BG had been servicing and passed year after year. They argued that the removed window vent more than gives the 15cm² required. IIRC it was around 9kw.
I argued the old MI's are out of date and AR'd fire. Customer was not interested in forking out to upgrade ventilation to 100cm².

 

[Rob Sale]

Mi's trump regs.

 

[Puddle]

Mi's trump regs.

not as regards to updates in ventilation requirements

 

[Reg Man]

Just because a DFE is under 7 kw does not mean it does not need added ventilation,all DFE's need ventilation unless otherwise stated by manufacturer and that ventilation shall be no smaller than 100cm2

Agree with you. British Standard 5871 part 3. All DFE fire installations require in a minimum 100cm2 free air ventilation unless the manufacturer for the appliance specifies otherwise. DFE fires less than 7kW may not require additional ventilation if the flue flow is greater than 70m3/h, manufacturer would have to be consulted before accepting this as acceptable.

 

[arran197]

DFE's require a MINIMUM of 100cm2. End. If the M.I.'s recommend more then it must be provided. If less then 100cm2 is needed. The adventitious ventilation does not suffice for DFE's. Are you sure it's a DFE and not and LFE?

 

[sparra1100]

all dfe,s have to have 100cm" regardless and as above if mi,s say bigger you go bigger but carnt be less than 100cm2 full stop

 

[AlexGas]

No, no, no...
OK, BS can be confusing...
Here's same thing in our good old TB from Gas Safe:

Technical Bulletin 041

Note 2: DFE appliances with a rated heat input less than 7kW (Net) will normally require a minimum of 100cm[SUP]2[/SUP] free-area ventilation, however, reference should be made to the manufacturer’s installation instructions, as some models may not require additional ventilation.

Note 3: DFE appliances with a rated heat input greater than 7kW (Net) and up to 20kW (Net) will normally require a minimum of 100cm[SUP]2[/SUP] free-area ventilation, (or as by manufacturer’s installation instructions).

It's in black and white. So, it can be less than 100 cm[SUP]2[/SUP] or none.

 

[GrahamM]

Mi's trump regs.

In the majority of cases yes, but with important issue such as ventilation requirements the Regs/Standards overrule.

Another example is, how many sets of MI's does it state the flue must be fully inspectable along it's run?

Sometimes we have to take a balanced view/approach between the MI's and regs!

Nothing is straightforward in this game. Even more so in recent years. We now have more and more MI's contradicting regs/standard and vise versa. Keeps us on our toes.:smile:

 

[ADM360]

I could be wrong but I though that you couldn't just cut a hole in the floor to give a vent to a fire, I was under the belive that if it was under the floor it had to be purpose provided ventalation and ducted directly from out side to the vent!!

 

[kirkgas]

I could be wrong but I though that you couldn't just cut a hole in the floor to give a vent to a fire, I was under the belive that if it was under the floor it had to be purpose provided ventalation and ducted directly from out side to the vent!!

floor vent only needs to be ducted if under floor communicates with more than one property or there is a potential for radon gas

 

[ADM360]

Thanks Kirk, I though someone would put me right!!

 

[sparra1100]

to be honest i couldnt care less what anyone says as on my acs its said 100cm2 and says the same in the corgi book and viper book so as long as i cover my own rear and no one dies al stick to what ive been taught granted the mi,s overule everything but its been 100cm2 for as long as ave been doing it and this is the first time anyone has questioned it so all i would say is if someone wants to take the risk so be it on there head but i no what i would do

 

[AlexGas]

to be honest i couldnt care less what anyone says as on my acs its said 100cm2 and says the same in the corgi book and viper book

Sorry mate, you have to read the books again.

CORGI book (page 72) For DFEs - check the MIs as some models may not require any additional ventilation - or as per MIs.

VIPER (page F-4) Decorative fires may not need purpose provided ventilation where the MIs clearly identify this.

 

[kirkgas]

Sorry mate, you have to read the books again.

CORGI book (page 72) For DFEs - check the MIs as some models may not require any additional ventilation - or as per MIs.

VIPER (page F-4) Decorative fires may not need purpose provided ventilation where the MIs clearly identify this.

im sure sparra will qualify what he means, but my interpretation of what he is saying is that DFE'e need either NIL or 100cm2, not a calculated value of 15cm2 or anything else.

 

[sparra1100]

im sure sparra will qualify what he means, but my interpretation of what he is saying is that DFE'e need either NIL or 100cm2, not a calculated value of 15cm2 or anything else.

yep kirkgas as far as am aware you carnt calculate anything with a dfe and has to be 100cm2 cos i asked wat if it has less ventalation and is ncs tutor said nope has to be 100cm2 so ave always gone with that regardless

 

[PB108]

The BS is the useful entry here, all else is just hearsay IMHO.

I have a case in point in that a certification company disconnected my gas fire as it's a DFE and gas bloke & his parent company say all DFEs need air ventilation 100cm2 to outside.
Without contacting me they did this then I got phone call later, so complying we put in an air vent before re-connection which is another load of dosh.

Then I discover my gas fire does not need air vent as manufacturers website states.

So even though spent on getting unnecessary air vent they want money - this must be happening worldwide and think of the resource (& carbon AGW scam) wastage.
Should not the burden of proof be on gas engineer to show model needs air vent rather than just cut off?

I wonder what GasSafe train the engineers to do?

 

[Last Plumber]

All DFE's need an air vent "unless manufacturers instructions say otherwise".

If you don't have the instructions to hand for your own equipment, most engineers would look at that it you either need to find them ( from manufacturers or internet ), or sign a warning notice and have it turned off until you do find them. The other option would be to forget finding them and put a vent in for it.

I personally might have a quick google to try and help the customer out but there are many DFE manufacturers around and many fires. A lot of manufacturers disappear without trace in my experience and a lot of DFE fires have little or no information. In other words, it isn't that easy in most cases to find information and a lot of people do not want to pay a gas Engineers fee for spending time trawling the internet.


I hope this answers your questions!

You know this thread is 5 years old ?

 

[Last Plumber]

All DFE's need an air vent "unless manufacturers instructions say otherwise".

If you don't have the instructions to hand for your own equipment, most engineers would look at that it you either need to find them ( from manufacturers or internet ), or sign a warning notice and have it turned off until you do find them. The other option would be to forget finding them and put a vent in for it.

I personally might have a quick google to try and help the customer out but there are many DFE manufacturers around and many fires. A lot of manufacturers disappear without trace in my experience and a lot of DFE fires have little or no information. In other words, it isn't that easy in most cases to find information and a lot of people do not want to pay a gas Engineers fee for spending time trawling the internet.


I hope this answers your questions!

You know this thread is 5 years old ?

 

[Dotty]

As a footnote. Your humble opinion is baseless and without merit.

 

[newcastle phill]

Underfloor ducting is only necessary for flueless appliances and its also necessary for ventilation provided through another room for flueless.
Open flue can be un-ducted thro floors

 

[Simon F]

The BS is the useful entry here, all else is just hearsay IMHO.
another load of dosh.
Then I discover my gas fire does not need air vent as manufacturers website states.

So even though spent on getting unnecessary air vent they want money - this must be happening worldwide and think of the resource (& carbon AGW scam) wastage.

I wonder what GasSafe train the engineers to do?

I have fitted a DFE that the manufacturers stated did not need a vent.But the size of the chimney opening made the draw on the flue insufficient.
So a vent gets fitted anyway.
The engineers judgement also is a key issue.


there is more involved in working with gas than just taking money from people!