High Flow duct sizes

[Hilldes]

Working on the MVHR spec with supplier. I've selected the option for Vent Axia Sentinel Kinetic High Flow MVHR unit. House is 260m2. 

 

The Vent Axia Sentinel Kinetic High Flow has larger 180mm spigots (150mm are more common I think).

 

The design features 180mm ducts and grills for the intake and exhaust to atmosphere. For the internal supply and extract, the distribution boxes have been specced with 150mm spigots. An adaptor will be supplied to step down from the 180mm spigots on the MVHR unit to the 150mm spigots on the distribution boxes. 

 

Stepping down from 180mm to 1500mm sounds like it defeats the point of the ***High Flow***.

 

Does this sound right?

[Alexphd1]

I would spec bigger pipe and connections at distribution box. 

[Hilldes]

2 hours ago, Alexphd1 said:

I would spec bigger pipe and connections at distribution box. 

Thanks @Alexphd1 that is what I’m inclined to do. I did question this with the supplier but I don’t think they got it.

[Alexphd1]

i went on the principle bigger ducts = less resistance = lower fan speed so less noise.