Inlet/Outlet location. Boiler flue consideration

[Oz07]

Sorry for all the threads regarding this, I have searched and came across very similar topics but none which seemed to answer my question.

Having a small service cupboard in new place. Will only have 600mm x 2400mm of external wall space available as the 'side' of the cupboard is against the external wall.

 

I'm trying to plan for inlet and outlet of MVHR. As the wall space available is so small my initial plan was the take MVHR through ceiling and out through vent tiles. If a boiler flue is on an external wall below this it suddenly doesn't seem such a great idea? I could extend these inlet/outlet through to the other side of the roof if it helps. These pipes/ducts would then be approx 4 metres away from unit. is this a problem or a better solution. With regards to spacing of the vent tiles is there a general rule I can work off? I understand the specific unit would have instructions but having not specified the exact unit yet i'm looking for someone to say - put them x metres away you'll be fine. Roofs going on in next two weeks so trying to get these vent tiles in early doors save going back up there.

 

There is the alternative of taking them out through the external wall below boiler flue, but again didn't seem best idea and thought I might not have enough room anyway?

[JFDIY]

Can you move the boiler flu instead?

[Oz07]

Yeh thats an option too. Not preferred though as i'd then have to seal around where it exits airtight layer and seems easier to do through wall. What kind of distances are normal for these MHVR pipes? Perhaps I have enough for all on the wall with inlet 300mm off floor, exhaust 1800mm off floor, flue 2100mm off floor?

 

I would prefer the 2 roof vents for the unit and the wall for the boiler. Seems simpler

[Temp]

Our MVHR inlet is about 6m away from the oil boiler flue and around a corner. In 12 years we have probably smelt the boiler 3 or 4 times. 

 

Hot air rises so I would not put the MVHR inlet above the boiler flue as very likely to get a problem on cold windless days.

 

 

 

 

[Oz07]

cheers @Temp hadn't seen your reply.

I'm not thinking playing safe and MVHR inlet and outlet on opposite side of house to boiler flue.

I've emailed a couple of firms who have quoted me systems but not really got an answer to -

Is there an ideal length of these intake and exhaust pipes to the unit? I reckon mine will be approaching 4 metres long going through a cold loft and connecting to an air vent tile.

I'm tiling the roof next week so could do with knowing if this is a good idea or a problem in having these ducts so long.

Cheers

[Oz07]

have just found this thread with good advice for future reference

How are all you fellow roof venters getting a downwards fall to a roof vent, taking duct up above and back down or just omitting the fall?

 

[Temp]

6 hours ago, Oz07 said:

I'm tiling the roof next week so could do with knowing if this is a good idea or a problem in having these ducts so long.

 

I can't really see a problem with long pipes between heat exchanger and outside.

 

It might be possible to get condensation in the outflow pipe hence the need for a fall. Our grill is in the eaves so getting a fall wasn't a problem. Never seen any water come out, nor from the eat exchanger drain tube.