Vent calculation !

[dboi78]

I will be doing my acs soon and have been going over my ventilation
And have looked at various literature but still not sure if u minus 7kw
For adventitious air when working out vent for multiple appliances if it includes a dfe ? Or is it just 100cm2 plus whatever the greater
appliance grouping ?

 

[dboi78]

No takers ?

 

[mikegas]

adventitious air is already factored in the 100cm2 for the dfe

 

[dboi78]

But do u still minus 7kw when a dfe is grouped with another appliance ?

 

[mikegas]

not sure what you mean here, if there was no adventitious air a room for example, then a dfe would require 135cm2 but there is so the dfe only requires 100cm2, so if you was to add another dfe you would require an extra 135cm2 because the first dfe has already used up the adventitious air, hope this makes sense

 

[dboi78]

Got u mike cheers mate, I like to think I'm fairly intelligent but the way some of these books are worded sometimes baffle's me.

 

[kirkgas]

But do u still minus 7kw when a dfe is grouped with another appliance ?

you and/or the manufacturer can only use the adventitious once, so if you have a room with a dfe needing 100cm2 (which includes the adventitious) then you cannot include it in your calculations, so when grouping the following appliances you will get: 2x 24kw room sealed boilers, 6kw dfe , 27kw open flue boiler, cooker, the room is 20m3, so vent calcs are:
RS appliances need 0cm2
flueless appliances need 0cm2 + openable window
OF appliances need 100cm2(dfe) + 27x5=135cm2(boiler with adventitious used on dfe) total 100+135=235cm2
so vent for this room is the largest group which is 235cm2 + openable window

 

[mikimac]

Got u mike cheers mate, I like to think I'm fairly intelligent but the way some of these books are worded sometimes baffle's me.

Don't get too stressed with trying to understand the books, when you're in the class & it's being explained it makes a lot more sense 😉

 

[kirkgas]

I will be doing my acs soon and have been going over my ventilation
And have looked at various literature but still not sure if u minus 7kw
For adventitious air when working out vent for multiple appliances if it includes a dfe ? Or is it just 100cm2 plus whatever the greater
appliance grouping ?

send me a PM with an email address and i will send you a ventilation tutorial i have made up for you to practice on,