No room for pipe!?

[gc100]

Hi,

 

we have a single story pitched roof small barn conversion construction underway . I have a problem however with the ducts for a room. Basically the end of the barn is the kitchen/living area, also having a pitched ceiling the follows the roof line. 
I recently got a quote for MVHR and they said that I would need and feed and return at opposite corners of the room which means I would need and ugly external duct running across the wall or ceiling.

 

iIreally want to avoid this so I have a couple of questions. Do I really need to have at opposite corners rather than just either side of the room? If it’s really needed at opposite corners are there any really thin/wide ducts I could run in the ceiling/floor

 

 Plan attached 

 

thanks

[ProDave]

i used the 75mm plastic radial ducting system, quite easy to box in a small pipe like that.  Either at the eaves, or along the ridge with a slight "flat top" rather than the ceiling going right to a point.

[MJNewton]

The corner-to-corner suggestion is just to maximise the crossflow or air but it's not an exact science so don't be to too concerned about compromising. 

 

With your idea about wall-to-wall were you thinking bottom-left to top-left? If so, that might result in less-than-ideal airflow on the right-hand side of the room. An improvement on that might be bottom-left (for the supply) to top-right (extract) with only the latter duct needing boxing in and this being at the kitchen end where it might be more aesthetically acceptable. 

[MJNewton]

To add: Could you hide the ducting under the kitchen floor cupboards and come up in a boxed-in corner to a vent at the top? 

[jfb]

I'm planning on running some of my ducting in my barn conversion at the apex like prodave has suggested and then between the rafters and to the edges of the room. I have a extra insulation on top of the rafters making it easier to use the rafters for ducting (still within insulation envelope). What is happening at rafter level for you?

[JFDIY]

I've use 225x25mm duct across my vaulted ceilings, to save space loss, not connected up yet but the cross sectional area is equivalent to two 75mm o/d (63mm I/d ) ducts.

 

The only tricky bit is getting from the 75mm ducts to the flat channel, can photo what I've done if interested.

[gc100]

21 hours ago, jfb said:

I'm planning on running some of my ducting in my barn conversion at the apex like prodave has suggested and then between the rafters and to the edges of the room. I have a extra insulation on top of the rafters making it easier to use the rafters for ducting (still within insulation envelope). What is happening at rafter level for you?

nee have a central hallway with a false level to run all the pipework down, but wasn’t planning to do this in the area. I suppose the most easy and to keep following the same ceiling height would to just carry this into the kitchen which would leave lots of room for ducting. I’m just wary of loosing height as I’ve already needed to add some extra floor height for various reasons.

[gc100]

22 hours ago, MJNewton said:

The corner-to-corner suggestion is just to maximise the crossflow or air but it's not an exact science so don't be to too concerned about compromising. 

 

With your idea about wall-to-wall were you thinking bottom-left to top-left? If so, that might result in less-than-ideal airflow on the right-hand side of the room. An improvement on that might be bottom-left (for the supply) to top-right (extract) with only the latter duct needing boxing in and this being at the kitchen end where it might be more aesthetically acceptable. 

yes I think this is the best compromise actually thanks

[gc100]

18 hours ago, JFDIY said:

I've use 225x25mm duct across my vaulted ceilings, to save space loss, not connected up yet but the cross sectional area is equivalent to two 75mm o/d (63mm I/d ) ducts.

 

The only tricky bit is getting from the 75mm ducts to the flat channel, can photo what I've done if interested.

Yes please if you can. Do you think that profile ducting will be noisy? 

[JFDIY]

Just took some photos from ground level, might be a bit grainy.

 

I'm using 100mm terminals, all ducting joints are from Toolstation but using manrose duct, because it can be purchased in 2m lengths (less joints) and it's a tighter fit into the TS joints than their own joints.

All joints sealed with domus Flexi joint sealer then taped

 

 

The tricky part was getting from 75mm semi-rigid, I'm using either a home brew adaptor for a single pipe to 100mm and channel connector

 

Or a TS air brick adaptor then onto a blauberg 204*60 channel connector which gets to twin 75mm semi-rigid where higher flow is required.

 

@gc100  Can't comment on noise, far from ready to couple up yet, but I don't forsee a problem.

Edited December 8, 2019 by JFDIY

[gc100]

Thats great to see, definitely opens lots of options for me as well.

 

Thanks

[JFDIY]

Just thought I'd add that although the duct is quoted as 25mm, that is internal height, so at the joints it's closer to 30mm on the outside if not a bit more .

[gc100]

On 08/12/2019 at 12:20, JFDIY said:

Just took some photos from ground level, might be a bit grainy.

 

I'm using 100mm terminals, all ducting joints are from Toolstation but using manrose duct, because it can be purchased in 2m lengths (less joints) and it's a tighter fit into the TS joints than their own joints.

All joints sealed with domus Flexi joint sealer then taped

 

 

The tricky part was getting from 75mm semi-rigid, I'm using either a home brew adaptor for a single pipe to 100mm and channel connector

 

Or a TS air brick adaptor then onto a blauberg 204*60 channel connector which gets to twin 75mm semi-rigid where higher flow is required.

 

@gc100  Can't comment on noise, far from ready to couple up yet, but I don't forsee a problem.

 

I'm got to sort my ducting at very soon. Just wondering how you got on with this in the end as I think I will do the same?

 

How do you calculate the airflow rates through this 225x25mm duct?

 

 

[gc100]

On 08/12/2019 at 12:20, JFDIY said:

The tricky part was getting from 75mm semi-rigid, I'm using either a home brew adaptor for a single pipe to 100mm and channel connector

 

@JFDIY I need to do the same - what exactly are you using here please?