kingfisher CF 150 with aspestos flue

[jtsplumbing]

1 sq inch per 5000 btu ater the first 7000 if my memory hasnt failed me

Almost right 1sq" per 5000btu in excess of 25000btu (7Kw)

 

[firemant]

thats what i was getting at but need to check that air vent as it usualyy ahs a bug screen inside so compromises the size of vent

Bug screen?
Not allowed.

 

[firemant]

Old Potterton Kingfisher 150 (150000 btu) 44Kw if vent direct to outside only needs one vent can be High or Low just use standard method of working out size of vent

Thought it was 10/5 cm High/low for CF to outside? Less 7kw allowance

 

[firemant]

Sorry. Thought we were in a compartment.

44kw?
(44-7)*5=185cm2.
The complication of fly screens reducing free air is irrelevant, in as far as they cannot be present

 

[Gasmk1]

Sorry. Thought we were in a compartment.

44kw?
(44-7)*5=185cm2.
The complication of fly screens reducing free air is irrelevant, in as far as they cannot be present

It's not irrelevant I said he needs to check that vent as that type has a fly screen if so he needs to remove and replace the vent.

 

[firemant]

It's not irrelevant I said he needs to check that vent as that type has a fly screen if so he needs to remove and replace the vent.

I apologise. I misconstrued your comment. I had it in my head that you meant that the calculation should be done taking the screen into account.
Obviously, fly screen awareness IS relevant, as you say.

 

[jtsplumbing]

I apologise. I misconstrued your comment. I had it in my head that you meant that the calculation should be done taking the screen into account.
Obviously, fly screen awareness IS relevant, as you say.

Those old type plaster vents didn't have a fly screen

 

[Gasmk1]

Those old type plaster vents didn't have a fly screen

well i have come across quite a few of this type over the years that have a fly screen so best to check

Plaster Vent With Fly Screen 225mm x 75mm

 

[DaveTidy]

well i have come across quite a few of this type over the years that have a fly screen so best to check

Plaster Vent With Fly Screen 225mm x 75mm

Agreed. There were many types of old plaster vents that came with a flyscreen stuck to the back as many of the louvres used to break easily when trying to remove them.

Generally when you had a plaster vent, you also had a terracotta vent on the outside which was very restrictive and passed very little air. The vents were large and generally too small; even the small holes in the terracotta were tapered so they looked smaller form the outside but were even smaller on the inside!

Again, many of these vents used to be blocked with cavity wall insulation. The flyscreen would stop it coming through the louvre and the terracotta would be so small they would just block.

All a bit negative but very relative; when you actually got a tape measure to the opening you would find many of them actually didn't have enough ventilation so best to check.

 

[DaveTidy]

Generally if one of these old plastered vents us present there us usually a terracotta vent outside that passes very little air due to it's construction so I would also be looking at this also as it us in the equation and more than likely insufficient.