Most efficient dMVHR

[sonicboom]

Has anyone fitted any dMVHRs ? are they any good ? I have a room that is too far out for MVHR so dMVHR is probably the most conducive solution, however, the efficiencies aren't very pleasing.

I have seen PRANA claiming 96% efficiency but I don't know how that scales as the temps drop.

[JohnMo]

why not use something like this - other makes are available

 

https://www.ventilationland.co.uk/en_GB/p/brink-indoor-mixfan-co2-controlled-up-to-70-m3-h/17927/

 

You use the MVHR to dump air in to the hallway instead of the room directly. This fan is installed above the doorway or in wall and sucks air from room based on humidity and/or CO2 levels. Air is drawn into room via door undercut.

[sonicboom]

11 hours ago, JohnMo said:

why not use something like this - other makes are available

 

https://www.ventilationland.co.uk/en_GB/p/brink-indoor-mixfan-co2-controlled-up-to-70-m3-h/17927/

 

You use the MVHR to dump air in to the hallway instead of the room directly. This fan is installed above the doorway or in wall and sucks air from room based on humidity and/or CO2 levels. Air is drawn into room via door undercut.

Thanks. It would work very well in a bedroom but the problem room is in fact the kitchen and I am not sure if it'll work as effectively since moisture is the bigger issue.

 

 

[JohnMo]

44 minutes ago, sonicboom said:

problem room is in fact the kitchen

No wouldn't work. Trouble is without extracting to the main MVHR you don't have a well balanced system, so not that much energy to recover.

 

So assume not on a new build? If your not super airtight (you may be) MVHR is pretty much a waste of time and you are better with on demand dMEV. 

[sonicboom]

1 hour ago, JohnMo said:

No wouldn't work. Trouble is without extracting to the main MVHR you don't have a well balanced system, so not that much energy to recover.

 

So assume not on a new build? If your not super airtight (you may be) MVHR is pretty much a waste of time and you are better with on demand dMEV. 

It's a 1960s build, and the property is extremely airtight in prep for mvhr. So there is no way around it then?

Edited December 9, 2024 by sonicboom

[Mike]

22 hours ago, sonicboom said:

I have a room that is too far out for MVHR

Too far out? What's the problem?

[sonicboom]

12 minutes ago, Mike said:

Too far out? What's the problem?

Its a single story extension with no way of access through the joists so would need to go out externally about 3-5m. I am not too keen on that - primarily aesthetics.

[Mike]

25 minutes ago, sonicboom said:

Its a single story extension with no way of access through the joists

Then maybe 25mm x 225mm rectangular ducting at ceiling level would be acceptable? If you don't like the aesthetics of boxing it in, you could drop the entire ceiling by 25mm, unless you have very restricted headroom.

[JohnMo]

Post a drawing of your extension/house

[sonicboom]

On 09/12/2024 at 23:32, Mike said:

Then maybe 25mm x 225mm rectangular ducting at ceiling level would be acceptable? If you don't like the aesthetics of boxing it in, you could drop the entire ceiling by 25mm, unless you have very restricted headroom.

Can you recommend rectangular ducting - this might work. Does it need to be 225mm though ?

[JohnMo]

3 hours ago, sonicboom said:

Can you recommend rectangular ducting - this might work. Does it need to be 225mm though ?

Blauberg? Just about any ventilation supplier.

[Mike]

7 hours ago, JohnMo said:

11 hours ago, sonicboom said:

Can you recommend rectangular ducting - this might work. Does it need to be 225mm though ?

Blauberg? Just about any ventilation supplier.

Yes, not difficult to find. Manrose and Polyvent are two brands, but there must be others. I've seen them squarer (but deeper) sizes, but 25 x 225mm is the thinnest I've come across.

[sonicboom]

Thanks guys. What about insulation of this form factor?  the insualtion makes up the bulk of the size i.e. 50mm, so it still amounts to 125mm.

[Mike]

1 hour ago, sonicboom said:

What about insulation of this form factor?

If this duct is running from the MVHR unit (or a manifold) to or from a ceiling terminal, and if the duct is on the warm side of the ceiling insulation, they you don't need to insulate the duct.