Boiler balanced flue - building carport around

[CompoSimmonite]

When I built my carport I stopped half way down the side of the house due to back door and central heating balanced flue. Now it's been decided to move door position ready for a conservatory at a later date so there is only the boiler flue that stops me expending the carport the full length.
I should add boiler is going to be changed at a later date for a modern unit with ducted flue so won't be a problem in the future.
However back to present
The flue is 1m from the corner of house measured to centre of outlet.
I can design carport extension so it JUST comes under the flue lower edge however intention is to leave a big gap around this flue pro tem that can be covered at a later date when new boiler fitted.
Plan therefore is to make a galv steel "duct" that is, say, 30cm below lower edge and open to the corner of the house plus around 60cm to the rear. This will be fully sealed so fumes can't enter the carport.
The original installation instructions for the boiler (I've got these even though boiler is 35 years old - what can I say "I'm a hoarder" ) simply state must not be installed within 30cm, measured vertically, of an opening window, not immediately below eaves or balcony, less than 60cm from any surface facing the flue. There are no requirement or specifications given to what clearance there should be around the sides of the flue.

Do people think the duct idea is sound ?
I know the proper answer is change boiler first but that simply isn't going to happen for probably another year and I want the carport extension built before this winter.

Cheers.

Paul H

 

[Kayos]

Do not modify a flue, it's dangerous and illegal

Also the 300mm rule is now out of date, so any change will have the meet the current regs

Balanced flues distances are dependant on heat inputs, but work on a minimum of 600mm from anything as a starting point

Flues in and above car ports are a huge grey area, I will post some specs of what is permissible if you like?

 

[CompoSimmonite]

Flues in and above car ports are a huge grey area, I will post some specs of what is permissible if you like?

That would be a great help - thanks.

 

[Kayos]

The legislation is a bit complicated
The flue must be a minimum of 300mm above any new car port roof and 600mm from an internal or external corner, if you wish to build the car port over the flue it must be a minimum of 600mm from the lowest point on the roof to the highest point on the flue and fully open at each end. The clearance to an opening in the carport must also now be 1200mm
The idea suggested above will possibly interfere with the free dispersal of p.o.c, and I would not recommend it; my best advice would be to get a qualified engineer to have a look.
The issue is not stopping p.o.c entering the carport, its the effects of reducing the air supply to the appliance, one of the biggest causes of CO
Stuff like this is becoming less relevant as the efficiency of older appliances is so bad nowadays they are mostly being replaced.

I recently replaced a Gloworm Spacesaver for a friend (30+ years old) but kept the cylinder and upgraded to a modern Y plan, this has resulted in gas bills being HALVED!

 

[Kayos]

unless your an adherent of Geoff from the Torygraph where they will prise your "old reliable boiler" from your cold wrinkled hands :P

Most old boilers are reliable, they have minimal simple parts but they are not efficient, most back back boilers were rated an optimistic 65% when new, a SEDBUK 2010 boiler will be 92% minimum

 

[brightspark]

Most old boilers are reliable, they have minimal simple parts but they are not efficient, most back back boilers were rated an optimistic 65% when new, a SEDBUK 2010 boiler will be 92% minimum

Most old boilers are reliable, they have minimal simple parts but they are not efficient, most back back boilers were rated an optimistic 65% when new, a SEDBUK 2010 boiler will be 92% minimum

even the new figures are over inflated i had new boiler fitted last year and nowhere near the suposed savings

 

[upinsmoke]

When I built my carport I stopped half way down the side of the house due to back door and central heating balanced flue. Now it's been decided to move door position ready for a conservatory at a later date so there is only the boiler flue that stops me expending the carport the full length.
I should add boiler is going to be changed at a later date for a modern unit with ducted flue so won't be a problem in the future.
However back to present
The flue is 1m from the corner of house measured to centre of outlet.
I can design carport extension so it JUST comes under the flue lower edge however intention is to leave a big gap around this flue pro tem that can be covered at a later date when new boiler fitted.
Plan therefore is to make a galv steel "duct" that is, say, 30cm below lower edge and open to the corner of the house plus around 60cm to the rear. This will be fully sealed so fumes can't enter the carport.
The original installation instructions for the boiler (I've got these even though boiler is 35 years old - what can I say "I'm a hoarder" ) simply state must not be installed within 30cm, measured vertically, of an opening window, not immediately below eaves or balcony, less than 60cm from any surface facing the flue. There are no requirement or specifications given to what clearance there should be around the sides of the flue.

Do people think the duct idea is sound ?
I know the proper answer is change boiler first but that simply isn't going to happen for probably another year and I want the carport extension built before this winter.

Cheers.


Paul H

HI Paul
I think one of the problems must be, although maybe well engineered, is that in advent of an insurance claim, you could be scuppered.
Flue pipe sections in enamel or stainless are cheap enough, making the conextion between the two systems could be a problem. As its a balanced flue in a bit of an restricted area you would need to have the inner tube the exhaust up and away from the outer air intake

 

[brightspark]

depends also on the controls, insulation, how sludged up or otherwise the system is etc...

y plan. rad valves fitted all been drained down took radiators off and flushed the tanks well lagged . it dont get any cleaner than that . the only reason the old one was taken out it was leaking

 

[Kayos]

even the new figures are over inflated i had new boiler fitted last year and nowhere near the suposed savings

If you can get 20 deg across the flow and return the figures do improve

 

[Kayos]

HI Paul
I think one of the problems must be, although maybe well engineered, is that in advent of an insurance claim, you could be scuppered.
Flue pipe sections in enamel or stainless are cheap enough, making the conextion between the two systems could be a problem.

Please please please dont post stuff like this, you are talking about 2 completely different types of flue, that in no way could or should be connected

 

[upinsmoke]

Please please please dont post stuff like this, you are talking about 2 completely different types of flue, that in no way could or should be connected

HI kayos
I did poin

Please please please dont post stuff like this, you are talking about 2 completely different types of flue, that in no way could or should be connected

Hi i did point out this would invalidate insurance. As a oil fired boiler guy, i do from time to time have to replace or redirect flue systems. I think the first
sentence of my post should have explained my view on doing the job

 

[Robotstar5]

To keep the thread off topic though, we had our old, hugely inefficient baxi boiler replaced with a super-modern, 164% efficient condensing unit - since then our gas usage has dropped not one iota (actual units of gas, not cost - the cost has risen) and we've seen a slight increase in electricity usage... This is on an equivalent month to month comparison based on monthly readings over the past 3 1/2 years...

Had our Baxi back boiler replaced a couple of years ago with a modern boiler and gas usage dropped by 28%

 

[brightspark]

gas usage is weather dependent the last few years havent been too cold the previous year was terrible

 

[optima21]

a couple of years ago I worked out that it would take 25 years to recover the cost of replacing my inefficient 37 year old Concord WRS boiler, due to the saving in gas usage. in that 25 years its likely that a new boiler will need replacing twice, so I think it'll be staying for a bit longer. I'll be cleaner and inhibitor in it again next week though.
I'm still a low user as I wear warm clothes rather than putting the heating on

 

[CompoSimmonite]

Plan B
Build carport extension frame ignoring flue. Then clad just part of roof leaving the area around the flue completely clear per the regulations. At later date change boiler and add roof to the area previously left clear.

 

[gaz1]

what you need to do is find out your boilers maximum flue length and can it use 2 elbows
some systems can use this method some cannot
most boilers fitting instructions are on the net in pdf form

 

[normspanners]

If you can get 20 deg across the flow and return the figures do improve

from my findings most plumbers just leave the lockshields fully open anyway, they cant be a$$ed/dont know how, to do the balance, so the high eff cant work. Have seen at least 4 recently all different plumbers that have fitted and left with the main setting up not even attempted.