ventilation fans uk

http://www.qvsdirect.com/Lineo-Standard ... 19049.html is this the correct type of fan for fresh air? thanks

Joey is it a requirement to actually have a fan for fresh air ? If you connected the fresh air supply very close to the return of the air handling unit (AHU) via T-piece into the room return (or other duct connection widget), I wonder if the AHU fan would suffice in drawing in fresh air to mix with the return air, prior to being conditioned ? Rod would know i'm sure ? The ventilation design issue is causing me no end of head scratching i can tell you!! good luck with it, i'll be watching closely for tips :wink:

I guess i should have also asked a question... If it is ok not to use fan as i desribe above, how close does the Fresh Air intake need to be and would distance of fresh air supply have a dependency on duct size ? cheers

as far as i know from reading here, you need mechanical ventilation for any room that does not have an opening to the out side world. i was thinking of using a mini split ac for ac and 2 of the fans at the top of the thread. one to pull air in and one to pull air out. not sure if you can use 1 fan on the exhaust side which would draw the inlet air in on its own. i think if you have the ducted ac with a air hander then the fan does the ob for you. but please dont hold me to it.

this is what i mean . sorry for crap drawing.

Hi Joey Here is my work in progress. I dont see where your air handler would be ?

where it says mini split is the ir handler in red. it is then connected to the externall unit via 2 pipe lines. (other red box). does this make sense?

it would be a stange world where I say what you have ducted in your drawing........ I have never seen a split take place at a fan coil unit - and they doin't like to have any such things occur for generally 6 times the duct width..... So you will probzably have to relocate your access door - and rething your ducting........ BUT - the good new is that you do not have to use a fan for fresh air if you connect directly (within a foot or so) of the air handler unit with a fresh air supply duct - and then just install a relief duct at least 10' DOWNWIND (thus still on the return air duct) of the inlet - this with a Barometric pressure relief mounted on it to adjust for positive pressure within the space....... I NEVER recommend 2 fans for this operation......... All you have to do is verify the static pressure at the inlet point - and then use this knowledge to size the fresh air supply duct - use a "Duculator" to determine the actuall size that works. Example - if you had 1" of static pressure at the inlet - then you could size the pipe for 6" - wide open using .5" of that static = which would feed you about 260 cfm - adjust the baometric damper to open at .01" static - and the system would balance out at about .1" of positive static pressure within the room - flow would drop to 250 cfm while maintaining the systems original 1" of static pressure on the original fan coil........ Use the fan you already have to your advantage. Save money long term on equipment costs - energy costs, etc. Rod

rod what do you think of the idea i have above? in your book it say s about using a mini split but not about how to get fresh air ventilation for a mini split. would you use somthing like above with a fan only on the exhaust side?

joey wrote:

rod what do you think of the idea i have above?

Joey, did you take the time to read my original response? Rod

im sorry but i dont understand. i thought your responce was to the other guy posting (johny p). my understanding being that if i have a mini split ac unit it would not feed fresh air but just condition what is there? if so surley i would need seperate ducts and a fan connected on the out let duct to remove stale air thus drawing in fresh air from the inlet duct via negative pressure.? rod i appreciate your help on this subject. i did read what you wrote but didnt realise it was aimed at me. here in the uk it is not common to have ac in homes so the understanding is poor, thanks joey

bump for rod thanks joey