MVHR pipe installation - how tight will they bend?

[Kernow]

Currently in the middle of DIY installing our MVHR system, and just wondering about the bends.

 

Some of our 90 degree bends seem a bit on the tight side, how tight have you bent your pipes?

I see you can get 90deg joints, am I better of getting some of these or are tight bends ok?

We are using ubbink 90mm semi rigid round ducting.

 

Any feedback would be appreciated.

[JohnMo]

We used ubbink 90mm, if you look on their website and datasheets they have all the details on pressure drop and bend radius.

[Chablais]

I used the same 90mm dia semi rigid ducting, it will bend to 90 deg if you have the space, otherwise i would use a 90deg connector. Smooth, large radius curves are always preferable, as all changes in direction will disturb the airflow and affect the pressure drop.

Be careful if going through pre made joists, put pads were the ducting touches any of the metal braces, and ensure they are secured well. A smear of silicone grease on the connector seals also helps installation.

Remember to label all the ducts as they land at the distribution box, and cap all the ducts if construction is ongoing to prevent dust ingress

 

Edited November 22, 2022 by Chablais
spelling

[Kernow]

1 hour ago, JohnMo said:

We used ubbink 90mm, if you look on their website and datasheets they have all the details on pressure drop and bend radius.

Thanks, have had a quick look. I think I will be ordering some bends, as some of ours are definitely tighter than the recommended 150mm radius. 
 

1 hour ago, Chablais said:

I used the same 90mm dia semi rigid ducting, it will bend to 90 deg if you have the space, otherwise i would use a 90deg connector. Smooth, large radius curves are always preferable, as all changes in direction will disturb the airflow and affect the pressure drop.

Be careful if going through pre made joists, put pads were the ducting touches any of the metal braces, and ensure they are secured well. A smear of silicone grease on the connector seals also helps installation.

Remember to label all the ducts as they land at the distribution box, and cap all the ducts if construction is ongoing to prevent dust ingress

 

 

Yes I understand that large smooth curves are better, it’s mainly on the vertical to horizontal junctions that are going to be a bit tight. 
 

Labelling - good point