vent on door

[geojack]

hi there ,
i have a back boiler heating system,the gas fitter told me i have no air brick in my sitting room so he told me i would have to put a vent in the door .
should i put it at the bottem or the top of the door and how big should the vent be
yes i know i sould have asked him, but for some reason i didnt.

thanks in advance

 

[migoplumber]

5cm2 per kw, is the rule of thumb - some times it's less

 

[geojack]

im not a plumber , that means nothing to me. i am thick.
should i just drill as many holes as the vent will hide.

do i do it at the bottem of the door

 

[kirkgas]

5cm2 per kw, is the rule of thumb - some times it's less

open flued ventilation is not rule of thumb, it is a defined calculation that should be calculated by someone who is clear on the rules, best to get gas engineer back to discuss the options for position/type etc, if you post the exact make & model of the fire & boiler we can work out the vent size for you, but best to have someone sort out the vents for you, as the actual type of vent fitted needs to be right, as well as the correct size.

 

[Billy Bob Bob]

as kirk says,give us make,model,and kw input rating we can work it out from there,trouble is you are on about cutting the max that a vent will hide typically 127 cm2 it may be less,you dont drill a series of holes you go to the aggregate size

 

[newbie1]

not that simple either vent cannot be at top must be no more than 450mm i think high and if in series will need to be huge as you need the combustion vent to outside then the clear path for air to the the boiler
that enginner should not have left your property with that boiler running
back boiler open flue prob about 20kw
so vent to outside air is 100cm sq as i assume it has a fire on front of boiler
these need correct amout of air for combustion that i would have classed as at risk and turned it off all air for combustion is being taken at present from the room and if door is closed only adventitious air entering room very bad of gas engineer to walk away from a open flue appliance with no ventilatio....was he a gas safe engineer or john wayne

 

[Puddle]

Well if he gave the customer no paperwork,no details of vent or his options ,left boiler working with not warning label,I would go with John Wayne

geojack,what was the reason he was there,get this ventilation sorted asap ,it is very important for your safety !!

 

[geojack]

hi mate
my boiler and fire is a baxi bermuda 45/4E

G.C.N 44 077 73

 

[newbie1]

well without seeing job my thought are 80cm sq vent is required for ventilation to outside air direct
so outside wall 80cm sq and through door again 80cm sq (2 vents in total one in door no higher than 450mm

but if outside wall vent and then passes another 2 rooms to reach boiler then
outside vent 80cm next vent 120cm and third vent 120cm
this is all based on boiler being range rated at 17kw gross heat input

orig engineer if he walked away with issuing warning and capping off boiler needs to be shot

 

[kirkgas]

hi mate
my boiler and fire is a baxi bermuda 45/4E

G.C.N 44 077 73

45/4E is the boiler we need to also know the model of the fire, (data plate is on left hand side of fire, Bermuda is the whole range,

also once the vent size has been agreed there is still the issue of having an gas approved vent type, properly fitted etc etc etc, get a gas engineer in, PLEASE!!!!!!!!!!!

 

[bikerbas]

Im just doing my gas trainning,if i remember its add both appliances together then deduct 7kw for adventurous air than x by 5cm2.

 

[Billy Bob Bob]

just to clarify kirk,and this is mi instructions on most of baxis burmuda range,fire is not taken in to account under 7kw, surprised me when i found that one out

 

[newbie1]

fire would account for the adventitious air
but the gist of this is that no vent is ar and should have been capped off

 

[geojack]

do you to vent the wall aswell can it not just be a vent in the door

 

[Billy Bob Bob]

yes thats right,i wont service one of these if no vent present,i always ask before attending

 

[geojack]

theres a air brick in the kichen but not in the sitting room where my fire and back boiler is why is n
this

 

[bikerbas]

I thought if it was AR you turn appliance off,and cap off when its ID

 

[stevetheplumber]

if you have a suspended floor you can use a floor vent

 

[geojack]

no i havent , i have solid concrete floors downstairs but outside on the kichen wall theres an air brick

 

[kirkgas]

just to clarify kirk,and this is mi instructions on most of baxis burmuda range,fire is not taken in to account under 7kw, surprised me when i found that one out

that is not correct, when calculation multi appliances (in this instance you treat them as seperate, i know they are classed as a combined unit) you add max HI of all open flued appliances in the room, divide by 1.1 to get to net if required (would prob be required on a BBU data badge will confirm) -7 then *5, so you dont discount a 6kw fire and count just the boiler

 

[Blackcatgas]

no i havent , i have solid concrete floors downstairs but outside on the kichen wall theres an air brick

like somone has just said vent size (cm2) = (maximum net input in kw-7kw) x 5.

so if you gas fired back boiler is 20kw:
20kw-7kw =14kw
14x5=70 cm2
a 70cm2 vent is about 100mmx100mm in size, get the correct one from a plumbers merchant.

if the air brick in the kitchen is the correct size needed and of the correct type (any old "hole" wont do) then you only need to put a vent in between the room with the boiler and the room with the air brick, (of 70cm2) if there is three or more vents in series then each vent needs to be increased to be 50% increments ie if you vented from the boiler room into the lounge then into the kitchen which has the outside vents.

Ventilation is very important, dont think that just because it "works" and "has done for years" that it will be ok, it wont one day.

 

[kirkgas]

no i havent , i have solid concrete floors downstairs but outside on the kichen wall theres an air brick

YOU NEED TO GET A GOOD GAS ENGINEER IN, AN AIR BRICK DOESN'T MEET THE CRITERIA FOR A GAS VENT, things are getting confusing as we discuss all the different bits & bobs for this.

 

[Blackcatgas]

I use the staduim black hole ventilators TM, they have internal baffels which cut down on any draughts and will fit a core drilled hole nicely.

 

[newbie1]

to original poster
get a competent gas safe registered engineer to your property to get correct ventilation for what is infact a death trap

 

[kirkgas]

like somone has just said vent size (cm2) = (maximum net input in kw-7kw) x 5.

so if you gas fired back boiler is 20kw:
20kw-7kw =14kw (20-7=13)
14x5=70 cm2
a 70cm2 vent is about 100mmx100mm in size, get the correct one from a plumbers merchant.


Ventilation is very important, dont think that just because it "works" and "has done for years" that it will be ok, it wont one day.

i agree that vents are important, but so is careful calculations!!!!!!
20/1.1-7*5= 56cm2, but this isnt accurate, as i said earlier it depends on what fire front is fitted, guys we are trying to advise the OP here and now confusing ourselves, a 45/4E with a PW5 fire needs 82cm2, but if it has a LFE5 fire it needs 86.68cm2 lets get it right or the poor OP is going to rip it all out an get an electric boiler fitted

 

[Blackcatgas]

i agree that vents are important, but so is careful calculations!!!!!!
20/1.1-7*5= 56cm2, but this isnt accurate, as i said earlier it depends on what fire front is fitted, guys we are trying to advise the OP here and now confusing ourselves, a 45/4E with a PW5 fire needs 82cm2, but if it has a LFE5 fire it needs 86.68cm2 lets get it right or the poor OP is going to rip it all out an get an electric boiler fitted

doh!

i agree that vents are important, but so is careful calculations!!!!!!
20/1.1-7*5= 56cm2,* but this isnt accurate, as i said earlier it depends on what fire front is fitted, guys we are trying to advise the OP here and now confusing ourselves, a 45/4E with a PW5 fire needs 82cm2, but if it has a LFE5 fire it needs 86.68cm2 lets get it right or the poor OP is going to rip it all out an get an electric boiler fitted

*Gross input

like somone has just said vent size (cm2) = (maximum net input in kw-7kw) x 5.*

so if you gas fired back boiler is 20kw:
20kw-7kw =14kw
14x5=70 cm2
a 70cm2 vent is about 100mmx100mm in size, get the correct one from a plumbers merchant.

if the air brick in the kitchen is the correct size needed and of the correct type (any old "hole" wont do) then you only need to put a vent in between the room with the boiler and the room with the air brick, (of 70cm2) if there is three or more vents in series then each vent needs to be increased to be 50% increments ie if you vented from the boiler room into the lounge then into the kitchen which has the outside vents.

Ventilation is very important, dont think that just because it "works" and "has done for years" that it will be ok, it wont one day.

* net input.

 

[plumbdocter72]

hi there ,
i have a back boiler heating system,the gas fitter told me i have no air brick in my sitting room so he told me i would have to put a vent in the door .
should i put it at the bottem or the top of the door and how big should the vent be
yes i know i sould have asked him, but for some reason i didnt.

thanks in advance

if the boiler is in a compartment you will need ventilation at high and low level and you will need ventilalatio from an out side wall as well.

to work out the size you have to take the kw of your boiler eg 20kwx5cm=1oocm2 .As for the door it is eg 20xkw of boiler, bottom and 10xkw top if your ventilation is direct from outside into your compartment you will have to use a different formula hope this helps.

 

[Billy Bob Bob]

that is not correct, when calculation multi appliances (in this instance you treat them as seperate, i know they are classed as a combined unit) you add max HI of all open flued appliances in the room, divide by 1.1 to get to net if required (would prob be required on a BBU data badge will confirm) -7 then *5, so you dont discount a 6kw fire and count just the boiler

unless mi say other wise which baxi do

 

[kirkgas]

unless mi say other wise which baxi do

i might be missing something on this, are you saying baxi say in the instructions to discount the fire and only supply a vent for the boiler? if so why is there different levels of ventilation for 2 different boiler/fire combos (with both fires being below 7kw) or are they quoting specific vent requirements for different fire/boiler combos because they are working it out for us, complying with BS5440 pt2, and using the formula i quoted. ie max HI of (boiler +fire)/1.1-7*5. ie 16.49+4.67 (if using PW5) /1.1-7*5=61.18cm2
the boiler the OP has is a 45/4E which has a HI of 16.49kw, so if i understand you correctly if we ignore the fire the vent is 16.49/1.1*5= 74.95cm2,
i appreciate MI supercedes everything else, so i just want to be clear what BAXI are saying in their MI's
cheers

 

[sas]

Well done mate. Not many peoples know about room size calculations and what type of vent they need or whats the combustion may result in their property. This is why the gas and cowboys never mix but still most peoples trust the cheap estimators.

 

[Billy Bob Bob]

i might be missing something on this, are you saying baxi say in the instructions to discount the fire and only supply a vent for the boiler? if so why is there different levels of ventilation for 2 different boiler/fire combos (with both fires being below 7kw) or are they quoting specific vent requirements for different fire/boiler combos because they are working it out for us, complying with BS5440 pt2, and using the formula i quoted. ie max HI of (boiler +fire)/1.1-7*5. ie 16.49+4.67 (if using PW5) /1.1-7*5=61.18cm2
the boiler the OP has is a 45/4E which has a HI of 16.49kw, so if i understand you correctly if we ignore the fire the vent is 16.49/1.1*5= 74.95cm2,
i appreciate MI supercedes everything else, so i just want to be clear what BAXI are saying in their MI's
cheers

this is what baxi technical have told me on several of there bermuda installs,for example a burmuda 401 with a gf fire came out at 66.6 cm2,but i always clarify dependant on model

 

[kirkgas]

this is what baxi technical have told me on several of there bermuda installs,for example a burmuda 401 with a gf fire came out at 66.6 cm2,but i always clarify dependant on model

i think we are talking about the same thing after all, calculating these models work out at this value, i think it is perhaps the way we are describing it, BAXI are not ignoring the gf fire they are combining both HI's as per BS5440 pt2