commercial flues, confused

[ambrosia]

in domestic which is what i'm used to, if its a room sealed appliance the flue is not allowed in a void unless you can inspect every joint. if its open flue as the flue isnt under possitive pressure youre okay. as theres no domestic open flued boilers ive ever heard of everything was clear

however i've just started doing commercial and those boilers often have a fan while still being open flue. I've been told the rules are different with commercial, however in my unsafe proceedures book there is no distinction, its says if its room sealed or fan draught, flue must be inspectable through out its length

 

[Gasmk1]

there are lots of open flued domestic boilers they are just old boilers but there are still plenty out there

 

[king of pipes]

Time to get your commercial training books out ambrosia i think your getting a little confused , there are still plenty of floor standing open flued gas boiler out there and many of them all you can see is the stove enameled section of the flue disappearing into the chimney which is then attached to a stainless steel flue liner which carries the flue gases up to a terminal and out to atmosphere these joint cannot all be inspected . on modern condensing gas boilers the flue and its joints need to be visable so it can be examined for leakage if its all boxed then there should be a removable access panels for every joint so it can be examined . opened flue fan draught you would normally be able to see all the flue and its joints it more like duct work with a fan that pulls in air from outside through a wall mounted grille and passes it over the flue connections which then dilutes the flue gases which are then disscharged through another grille usually on the opposite side of the building the fan is interlocked with the boiler so if there is no draught i.e the fan fails then the air flow switch wont sense a draft and make to and fire the boiler hope this helps cheers kop

 

[ambrosia]

i just notice a typo in my original post i meant to say "as theres no domestic open flued boilers with a fan i've ever heard of everything was clear" sorry, 1st post wasnt very clear

problem with those books is they fail to keep up with the regs, try finding one which reflects the ncs updates

it wasnt so much the interlocked fans i was confused about, it was the riello type boilers which such gases and then blow them through the burner and into the chimney, or the wall hung remeha boiler which have been converted into open flue but work on a similar principal and both putting the flue on possitive pressure. These boilers are often in the basement with the termination on the roof

 

[king of pipes]

I suggest you down load the manufacturing instructions for the installation of these boilers and the flueing arrangements allowed they are duty bound to keep up with the regulations this may help you understand how they work on principle cheers kop

 

[Gasmk1]

dont know if any still out there but used to come acroos quite a lot of Flueboost fans years ago wired into the boiler where there was problem with the flueing
Flueboost | Specialists in flue gas extraction

 

[ShaunCorbs]

I might be missing something but how can an open flued boiler be positive pressure ??

You sure it wasn't as kop said forced intake ?? See a lot of these with central boiler houses where no chance of getting air in (via grills etc)

What boilers were they ?

 

[ambrosia]

"I suggest you down load the manufacturing instructions for the installation of these boilers"

commercial boilers often dont come with instructions in the way domestic boilers do, because the burner is made by one company, the heatexchanger boiler part another company etc
many of then also have pretty bad tech support if at all

"I might be missing something but how can an open flued boiler be positive pressure ??"
they still have a fan between the gas valve and the burner, fan is blowing the products of combustion up the flow. however the air intake is within the boiler room

 

[ShaunCorbs]

I know where your coming from there pre mix burners should be rx series if I'm remembering right

Riello have a very good tech line but find some of there engy don't know how to set them up

 

[ShaunCorbs]

pre mix burners don't do anything to the flue (may help the flow a smudge but nothing much) e.g. Turn it into a positive pressure all the fan does it suck are in and mix with gas, think of oil boilers (similar)

If you've just done your commercial you should have someone with you for servicing pre mix burners there not easy if you have to adjust them

For some reason my last post doubled