balanced flues

[stephen99]

I need to have a new oil fired boiler. I was looking at the Grant range.

I was looking at the Grant flexi-flue chimney liners and see that the balanced (red) option is £600+ compared to £300 for the conventional (orange) flue. That's a big difference in price.

The boiler will be situated in a kitchen with an extractor fan and as
you will know, the guidance in Approved Document J is, "For oil
appliances: limit fan capacities as described in OFTEC Technical
Information Note TI/112 and then carry out flue draught interference
tests as described in TI/112"

Where can I find a copy of Note TI/112 so that I can check the fan capacity is within limits (there is a cooker hood too).

Do I need to pay extra for the balanced option?

Thanks.

 

[jon26]

If you are going to the trouble and expense of having a new high efficency boiler fitted, then why are you trying to put an open flue on it... personally I would be wanting it with a concentric flue, the cost difference would be minimal... maybe cheaper. This will therefore not be effected by the mechanical extract fan.

Balanced flues are much more efficient with greater flueing options available.

 

[muggles]

If you have a conventional flue, the boiler will draw it's combustion air from the kitchen. This air will then need to be replaced. The usual method for this is to put in an air brick or install a black hole air vent.

OFTEC will have copies of the OFTEC technical documentation.

If the availability of combustion air in the room is going to be a problem, it's easier to install a balanced flue, then the combustion air is drawn down through one half of the flue, and the exhaust gases pass out the other half, eliminating the need for draught checks.

 

[simond]

You don't NEED to pay extra for the balanced flue option.

And I doubt your installer is suggesting it to make extra money, it would be because it is a better solution.

By all means have an open flue, but you will need an extra large air ventilation aperture to help circumvent the negative pressure caused by the kitchen extractor.

So whilst you don't need a balanced flue, you probably don't WANT a massive draught and noise either .

 

[stephen99]

If you are going to the trouble and expense of having a new high efficency boiler fitted, then why are you trying to put an open flue on it...
Balanced flues are much more efficient with greater flueing options available.

Thanks for all the replies, I will pay for the balanced option. BTW how are they more efficient?