Fan flue proximity to opening window/vent

[Backboiler]

Assuming the mi's state the normal 300mm distance from the fan flue termination, to an opening window/extractor. Am I correct in thinking if the distance is less than 300mm and the opening is above the flue, I would classify it as AR but if the opening is below or to the side of the flue it would be NCS?

 

[Hardy1]

im sure all three are NCS, but all would have to be checked.

 

[diamondgas]

Assuming the mi's state the normal 300mm distance from the fan flue termination, to an opening window/extractor. Am I correct in thinking if the distance is less than 300mm and the opening is above the flue, I would classify it as AR but if the opening is below or to the side of the flue it would be NCS?

Truth is it could be NCS, AR or ID I believe! It all depends on whether there's a risk of the fumes re-entering the building and/or fumes have been reported! Check out GIUSP, TB001..

 

[Backboiler]

I see. If there has been reports of fumes etc then obviously ID. If no-one has reported fumes then the situation would require a risk assessment which would involve carrying out an ambient air assessment using an ECGA in acccordance with BS 7967-2 to determine if levels of CO are above or below 10ppm. If above it would be ID, and below AR but when would it be NCS?

 

[GrahamM]

Think you are complicating things here.

If less than the 300mm it is simply NCS.
Only if you know it is drawing in POC to the room through the opening, it would then be ID.
If the flue was 100mm form an opening and in your opinion it may draw in POC's, then you may use your judgement and call it AR.

 

[mountainman]

I see. If there has been reports of fumes etc then obviously ID. If no-one has reported fumes then the situation would require a risk assessment which would involve carrying out an ambient air assessment using an ECGA in acccordance with BS 7967-2 to determine if levels of CO are above or below 10ppm. If above it would be ID, and below AR but when would it be NCS?

That's cleared that up then! )

 

[Backboiler]

Think you are complicating things here.

If less than the 300mm it is simply NCS.
Only if you know it is drawing in POC to the room through the opening, it would then be ID.
If the flue was 100mm form an opening and in your opinion it may draw in POC's, then you may use your judgement and call it AR.

It's not me who wrote the GIUSP. In truth there are many grey areas within the GIUSP which may lead to complications due to objective interpretation. For example; as you wrote, how would "you know if its drawing in POC" or not if you didn't do a risk assessment? How would you know when to suspect it? What if the terminal was 200mm from an opening and the check was carried out on a still day? You classed it as NCS because you didn't consider it a danger. If the check had been done a day earlier when there was a strong wind blowing in the direction of flue to opening suddenly it's dangerous. Personally I would take away this grey area and do away with NCS, I would still have three classifications ID, AR and SAFE to use.

 

[diamondgas]

It is one of the greys that is turning ever so blacker towards AR - We'll soon be faced with a scenario of AR less than 300mm if fitted after such and such a date, NCS if before IMHO!

 

[mountainman]

Much too complicated.
I err on the side of 'if it's safe when I tested it and I consider tha it's safe after I leave then It's Safe'

Check your MOT certificate and it says much the same.

 

[GrahamM]

It's not me who wrote the GIUSP. In truth there are many grey areas within the GIUSP which may lead to complications due to objective interpretation. For example; as you wrote, how would "you know if its drawing in POC" or not if you didn't do a risk assessment? How would you know when to suspect it? What if the terminal was 200mm from an opening and the check was carried out on a still day? You classed it as NCS because you didn't consider it a danger. If the check had been done a day earlier when there was a strong wind blowing in the direction of flue to opening suddenly it's dangerous. Personally I would take away this grey area and do away with NCS, I would still have three classifications ID, AR and SAFE to use.

My boiler flue is approx 500mm from my back door. On a windy day I get the odd whiff of POC coming in the door. It happens. The flue is not close enough to constantly draw in POC's. If it was 290mm from the door, more than likely it would still be safe....And most are. I NCS at least one a day for this. But you want to AR this?

You want to AR a vertical flue because it is too close to a chimney breast as you want to do away with NCS classification?

If you think 290mm for example is too close for a flue to an opening window then by all means spend an extra 30mins carrying out an ambient assessment on each one you come across.

I will continue to NCS as long as customer has given no indication of any issue, and as far as I am concerned all is well during visit.

 

[Dannypipe]

I had to AR a boiler today. The flue was inbetween two windows. Was 180 from one, and 210 from the other. It was touching the soffit board above.

It was also 500mm from a wall opposite.

I hate being heavy handed, but the boiler needs new parts as I was called for a break down. Its in a pub, which is packed with tenants above.

I have to sleep tonight, so before I fixed the piece of junk and collected my cheque I thought I'd do best by the people who live in there. Even if it isn't the most popular option.

Apparently the fan was replaced last year and the engineer didn't mention the flue at all. Well look at the photo I took. He also left half the gasket hanging down in the boiler casing. (I know the engineer as I asked for his name, and I've had a run in with him a few years back, when I got called to a new boiler that he'd installed. The clients called me as they were worried it may fall off the wall.

It was, he hadn't fixed it properly to a lath and plaster wall. Instead of doing it properly, he'd just fixed it to the laths).

Appreciate opinions on this. Its going to be a pig to replace.

 

[Pssst]

Also,and to further muddy the waters,are the measurements quoted in BS whatever for flue outlets the straight line measurements between a building opening and the point where the flue duct emerges or the measurement between the building opening and the actual discharge point of the flue?

I'm thinking about situations where the end/discharge point of a circular flue duct is not flush with the wall but the flue pipe emerges some distance from the wall i.e it hasnt been cut down..

 

[MattWeth]

Measure on the face of the wall - edge of flue to edge of opening.

It would be impossible to specify a distance to the point of discharge as every flue and installation is different.

 

[Backboiler]

My boiler flue is approx 500mm from my back door. On a windy day I get the odd whiff of POC coming in the door. It happens. The flue is not close enough to constantly draw in POC's. If it was 290mm from the door, more than likely it would still be safe....And most are. I NCS at least one a day for this. But you want to AR this?

You want to AR a vertical flue because it is too close to a chimney breast as you want to do away with NCS classification?

If you think 290mm for example is too close for a flue to an opening window then by all means spend an extra 30mins carrying out an ambient assessment on each one you come across.

I will continue to NCS as long as customer has given no indication of any issue, and as far as I am concerned all is well during visit.

No Graham no. If you read my post again I suggested three classifications; ID, AR and SAFE. If i deemed an appliance SAFE to use then it would be SAFE to use, just as you did/would if a terminal is only 290mm from an opening, then the classification would be your decision and your responsibility. Lets face it, NCS is nonsense, it allows us the ambiguity to sit on the fence. Why introduce new regulations if they are meaningless. Surely a new standard is introduced due to a risk or incident that has occured and caused danger to life or property since the standards were created. So if we are absolutely sure that a flue will not cause a fatality at a distance of 290mm from an opening, why not just classify it as SAFE? Alternatively, if you think it may be a risk you would classify it as AR or if spilling, ID

 

[kirkgas]

NCS has to stay as regs change for various reasons, and appliances fitted to the currenrt regs cant now be deemed unsafe (except flues in voids it would seem, but i dont disagree with that one) however i hate calling something NCS if it was NEVER fitted properly, that is a cop out for the idiots who didnt do the job properly in the first place, so i think we should have NOS Not to Original Standards) to capture all the jobs that were never right, and should be rectified

 

[glenno1]

you could contact manufacturer and ask them but id say less than 300mm is at risk because you cant know what it does in all weather conditions you can only know what it is doing while you are there