It looks similar to the Ubbink AE35SC ducts we have and look similarly engineered. I don't see any mention of an equivalent to the flow restrictors the Ubbink system uses though, and I think that's quite important so I'd check. Without it you're left with using the terminal vents to set the flowrates to each room, which is (a) trickier and (b) potentially more noisy.

Posted By: wholaaDo you like the Ubbink AE35SC ducts? Do they perform ok for noise?

Yes to both questions.

Can these ducts be used for kitchen extractors too?

Don't know, we don't have any extractors. :) We have a freestanding recycling cooker hood and an MVHR extract terminal maybe 3 m from it. I fitted an extract terminal that includes a replaceable filter because we got more dust/dirt than in other rooms. That arrangement works well for us.

Posted By: wholaaIf you had any flattened oval ducting, did you insulate it? I am in a house with three floors. I have MVHR with the unit in the attic, but its suffering from pressure drop in the kitchen and loud noise in the top floor so I am thinking of renovating my system and increasing the airflow in the kitchen so I can run the whole system at a slower speed

I didn't insulate the ducts specifically. They are all inside the thermal envelope and carrying air at room temperature (except when heating) so there's no need. The ducts are double-walled with an air gap between the two plastic skins, so I think they're probably self-insulated to some degree.

When the heater is on I think most of the heat is absorbed by and lost through the ducts. Only on the shortest duct runs does the air coming out of the terminal feel warm. I don't care though because all I need is for the heat to be absorbed and warmed somewhere in the heated envelope, from where it will slowly spread throughout the house.

The kitchen is the only duct run in our house where dual ducts were specified. The design extract rate is high and the duct run was long so it needed two ducts. But the system is designed to allow that.

Our MVHR is a Brink Renovent Excellent 300. Its nominal capacity is 300 m³/hr, but as delivered its standard maximum flowrate is 225 m³/hr. It has a trickle rate of 50 m³/hr (intended for when the house is empty) and two other rates that we set to match the building regs continuous and purge rates, which are 125 m³/hr and 165 m³/hr. The two lowest rates are basically inaudible. Purge rate is audible if you listen for it and max is noticeable but not objectionable. With only two of us in the house we normally run it at 50 or 125 m³/hr.